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Pelican Technical Article:

BMW E30 3 Series Idle Speed Troubleshooting
Jared Fenton
Wayne R. Dempsey

Difficulty Level: 2
Difficulty scale: Adding air to your tires is level one
Rebuilding a BMW Motor is level ten

     One of the most common glitches on the BMW E30 3 Series is an erratic engine idle. Have you noticed that the idle seems to surge constantly? Does it constantly move between 800 and 1800 RPM? Does the idle stay steady at 1800 RPM? In this tech article I will go over the steps involved with checking the idle system and vacuum hoses. This article is intended for you to learn a little something about your car, and at the same time, point you in the right direction towards fixing that erratic idle.  Keep in mind that this article is specific to the 1987 through 1991 E30 6 cylinder cars, however the basics apply to nearly all BMW’s.  

     First off, most modern BMW’s from 1986 and on use the Bosch Motronic fuel injection system. The Motronic system is probably one of the most reliable fuel systems on the market, and is still widely used in most European cars. While the system normally requires no adjustments, over time, heat and age will start to take it’s toll on the various vacuum hoses on the engine. When vacuum hoses age, they dry out and crack. The result is vacuum leaks. A vacuum leak will usually cause the car to idle higher. The reason is simple. You are introducing more air into the engine. If you look at the throttle body or carburetor of any car, it is essentially a valve or a series of valves. When you begin to open the valve, air is able to flow into the engine, increasing the engine speed. With a vacuum leak you are getting the exact same result. In some cases, even a leaking valve cover gasket or oil filler cap can cause this leak, so make sure your valve cover is properly sealed.

     To begin to diagnose the idle problem, we will need to first need to look at the vacuum hoses. In this case, I have decided to replace all the hoses just for extra insurance. Vacuum hose is cheap, so you might as well replace all the hoses. Now look at the passenger side of the engine at the top of the valve cover. Loosen the hose clamp on the hose coming out of the top of the valve cover. Now, follow the hose to the other connection on the throttle body. Loosen the hose clamp and remove the hose. This is the breather hose. It is an important part of the vehicle’s emission system. It is used to recalculate oil vapor back into the engine to be burned again, rather than venting it out into the atmosphere. I found that the breather hose from the valve cover to the throttle body has an interesting size. One end is 14mm and it sizes up to 22mm on the other. You’ll also notice that this hose is formed in such a way that it will clear a bend on the intake manifold. Rather than trying to splice together two different size hoses and snake them around the intake manifold, I simply ordered the OEM hose from BMW to save time. (Pelican carries this hose for $6.30) Now snake the new hose into position under the valve cover and slip it on to the valve cover and tighten the hose clamp holding it in place. Do not connect it to the throttle body at this time.

     Now look above the valve cover on the intake manifold. You will see two small 3.5mm vacuum hoses. On the left side, the hose is plugged up, on the right side; the hose connects to the fuel pressure regulator. This hose is used to help control the fuel pressure on the car using engine vacuum. Just remove the hose clamps on either end, and pull the old hoses off. Now cut the new hose to the same length as the old ones, push them on and tighten the hose clamps.

     With those hoses installed, now look at the driver’s side of the engine down by the air cleaner. You will see the Air Mass Sensor bolted to the air box. One the other end of the sensor, there is a hose clamp that holds the intake air boot to the sensor. Loosen the hose clamp and carefully pull the air boot off the sensor. (Note: you may find it easier to remove the boot by taking out the air box completely. Unplug the air sensor, and just remove the two 10mm nuts holding to the bracket and pull it out.) Now look at the top of the air boot. You will see two fittings looking form the top. On the left side is the fitting for the idle control valve. On the right side is the vacuum attachment for the power brakes. Start out on the right side and loosen the hose clamp holding the brake fitting into the intake air boot. Now, on the right side, disconnect the electrical connector from the idle control valve, and remove the rubber strap holding the valve to the bracket. Now look at the other vacuum hose off the valve. We will simultaneously have to pull the valve out of both hoses. You may need to use a bit of force, however it will just pop out. If it hasn’t already come off, remove the vacuum hose going from the control valve onto the throttle body fitting. 

     With all the fittings out of the intake air boot, now loosen the hose clamp holding the boot to the throttle body. Now take the boot off. Before you continue, inspect the intake air boot for cracks. This is a common location for vacuum leaks. If you see any cracks or holes in the boot, replace it with a new one. Pelican carries these boots for $12.67. Now, look down under the throttle body. You will notice a vacuum hose attached to the throttle body, this is part of the emission control system. You should be able to just pull this hose off. Cut a section of new hose to the same length as the old one, and using hose clamps, attach it to the throttle body and the valve below.

     Now before we begin to re-install the boot and other items, we will need to check the throttle switch on the bottom of the throttle body. This switch is used to control the idle control valve. If this switch has a fault, it will cause the idle control valve to operate incorrectly. In order to test the switch, first remove the electrical connector from the switch. Just push down on the metal wire, and pull it off. Inside you will see three terminals. From the left, they are numbered 2 then 18 then 3. First, connect a digital multimeter between terminals 2 and 18. Now open the throttle halfway and slowly let it close. When it is between 0.20 and 0.60mm from it’s stop, check for continuity between the terminals. Now, connect the multimeter between terminals 3 and 18. Now open the throttle slowly.  Check for continuity when the throttle switch is within 10 degrees of being fully open. If you don’t see continuity while testing the terminals, loosen the screws on the bottom of the switch, and adjust the switch until it comes within these values. If you still do not have continuity, this means that the switch is bad and must be replaced. Pelican can provide you with this switch if needed. If the switch is good, re-connect the connector onto the switch.

Once you have tested the throttle switch, the next step is to test the idle control valve.

     The idle control valve controls the amount of air that bypasses the throttle butterfly and keeps the engine idling. The throttle switch is used to control the idle control valve. Essentially, when the throttle is fully closed, the throttle switch sends a voltage to the idle control valve. This voltage opens the valve and allows air to pass, increasing idle speed. Now, connect the multimeter between the two outer terminals on the valve and check for resistance. There should be around 40 Ohms of resistance. Now check the center terminal and each of the two outer terminals. There should be roughly 20 Ohms of resistance between them. If you do not get these values, the switch has gone bad and must be replaced.

     Now, we will continue re-installing the various components of the intake system. First, take the new breather hose from the valve cover, and push it onto the port on the side of the throttle body and tighten the hose clamp. Next, re-install the intake air boot, and tighten the hose clamp that holds it on to the throttle body. Re-install the fitting for the brake booster and tighten the hose clamp. Now re-install the idle control valve into the intake air boot and into the fitting on the side of the throttle body. Re-connect the electrical connector and rubber strap onto the valve.

     The last step is to re-connect the mass airflow sensor into the intake air boot and tighten the hose clamp. Re-connect the electrical connection to the sensor. Now start the car and listen to your idle. If everything in within spec, you should have a smooth idle between 700 and 900 RPM.

     Well, there you have it - it's really not too difficult at all.  If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs.  If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one.  Your continued support directly affects the expansion and existence of this site and technical articles like this one.  As always, if you have any questions or comments about this helpful article, please drop us a line.

Comments and Suggestions:
John Comments: Hello! I have a 1986 325e E30. Unlike the ICV you describe above, my unit has only two electrical terminals. When I checked the resistance between the two terminals, I got 9.4 ohms with an internal resistance in my meter of 0.2 ohms. Is this reading within range? What happens when the ICV resistance goes out of range? Also, do you have a photo showing the location of the throttle switch? Thanks!
July 26, 2014
  Followup from the Pelican Staff: I do not have a photo of the throttle switch location. I also don't have a spec handy for your valve. If resistance goes down, it will not operate as expected, worse case it can short the controller. I would grab a repair manual.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 
Michaele30 Comments: Good morning, I have a 1990 325i E30,and the car idles high when it's on Park or Neutral. I changed the ICV and saw that there is not vacuum leaks. What might be the problem or what should I check next in diagnosing the problem? Thank you for your help, it's greatly appreciated.
-Michael
July 15, 2014
  Followup from the Pelican Staff: This could be a faulty idle control module. Check the control signal to the idle control valve.- Nick at Pelican Parts  
And73w Comments: Hi, I have a 1995 BMW e34 518. I have a problem on start up. She starts fine, runs for 30 seconds to a minute then the idle drops and almost stalls. If I'm driving when this happens the car sort of chokes and almost all power goes. This happens for about a minute then she is fine. I've been told its the exhaust, and also told it's the MAF. Can you help please?
June 17, 2014
  Followup from the Pelican Staff: You could have a vacuum leak or a fuel delivery issue. I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
True Comments: HiGuys I have a 316 e30 carb Bmw. tha carb is giving me endless problems . Can I fit a VW 1.8 Jetta Carb on with an ajustment plate. Plse help
June 14, 2014
  Followup from the Pelican Staff: I don't think so. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
dropzone Comments: Yup , my engine missing fuel injector pulse at the same time . Sure need to change new one . Tq Nick for ur reply .
June 2, 2014
  Followup from the Pelican Staff: Then I would suspect a crank sensor. - Nick at Pelican Parts  
dropzone Comments: Tq Pelican Parts for ur advise . Regarding with my BMW E30 problem , i have change new spark plug , check all 6 fuel injector which all have pulse , changing new engine oil and got pressure fuel . Last few day as i said engine can start but automatically stop in few minutes . Open one plug and check got spark or not . Result - totally no spark . Is it crank sensor problem cause i read a lots of comment if crank sensor problem engine wont start . Is it true ? thqnks
June 2, 2014
  Followup from the Pelican Staff: It could be a crank sensor issue. Are you missing fuel injector pulse at the same time? Your vehicle has an engine speed sensor and a cylinder ID sensor. Both read signal from crankshaft position. - Nick at Pelican Parts  
roller Comments: Hello, i scan my car its a 2000 BMW 323i and its already months with my car in my garage i cant turn on the car, turns on but the throttle body doesnt accelerate totally nothing, and push the accelerator all to the bottom and doesnt accelerate, and the CODES that i have in the scanner is throttle body fail, but i already put 3 used and 2 new throttle body and still the same problem in my car, and i already check all the continuity of the wires all are working perfect, so do you think i need to reset with a special scanner or computer or the TBA trick??? and tell me the correct steps for TBA or maybe another trick or relays or sensors that i need to check
May 31, 2014
  Followup from the Pelican Staff: You may have a wiring issue, a faulty DME or require an adaptation. I would start by resetting vehicle adaptation using a BMW scan tool. Then rechecking the fault codes. - Nick at Pelican Parts  
dropzone Comments: Hi guys . Im have got one bmw e30 1980 from my friend . this car actually not started almost 1 years . Now this car started already but a few minutes automatic engine stop . May someone give any ideas what is the problem ?
May 26, 2014
  Followup from the Pelican Staff: I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
JKE Comments: On my '90 325is, I have two idle issues... First, during a cold start, the engine tends to continue revving between 700-1100 for a minute or two. In addition, while in neutralcold or warmed, if i depress the throttle and let it fall back to normal, the car will stutter for a moment.

Any ideas?

Thanks.
May 19, 2014
  Followup from the Pelican Staff: Sounds like there may a misfire, possibly caused by a vacuum leak. I would start by checking the engine for vacuum leaks. - Nick at Pelican Parts  
David Comments: Hey my 1991 e30 idles at 400-500 could the ICV be the one doing this? because I cleaned my ICV and forgot to plug the connector to it so I was running around 900 with it unplugged from the electrical connector.
May 15, 2014
  Followup from the Pelican Staff: The problem could be the ICV or the ICV module. - Nick at Pelican Parts  
gbs Comments: Hi, i have 325i 2006 bmw engine keeps coming back on as the car chugs shakes and idles rough. i have put in a new cam sensor,cabin filter, 2 new coils,6 spark plugs,2 oxygen sensors and cleaned hoses and maf. Do u have any idea what the problem can be it also gets worse when it is cold? thxs
May 13, 2014
  Followup from the Pelican Staff: SOunds like a misfire. I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
Matt Comments: My 1986 325e idle jumps to 3500 once i turn it on? It started to do this when i was trying to clean the ICV. could that be the problem?
May 12, 2014
  Followup from the Pelican Staff: COuld be a faulty ICV or ICV module. I would start by checking for vacuum leaks. - Nick at Pelican Parts  
Jake Comments: I've got an 86 325 that had a surging idle 800-1800. I replaced the idle control computer and the surge is gone... But now the car won't start unless I pull the engine coolant sensor off. The car was fine until I started chasing the idle problem, and now I have a mixture problem. No adjustment of the ICV seems to help. Fuel pump and all the temp sensors check good. Any ideas?
May 1, 2014
  Followup from the Pelican Staff: You could have an issue with the cold start valve or the temp sensor. I would go back over what you tested and see if something is plugged in wrong or disconnected. - Nick at Pelican Parts  
e30 Comments: Hi i have a 91 BMW 318is. my car starts but shuts down immediately when cold also misfires while shifting gears and when going on constant speed check engine light comes in when accelerator released it goes off. I have changed plugs, wires, fuel filter but still no effect on misfiring. I am having this problem from more than a month now.
April 29, 2014
  Followup from the Pelican Staff: Sounds like there is a lot going on. Focus on one of the issues and you will likely find the root of them all.

Is the check engine light on now? It does sound like an engine misfire. I would check spark, fuel and compression on all cylinders.


- Nick at Pelican Parts
 
JG825 Comments: I have a 1984 318i and the idle has been high - although occasionally it settles down. When removing all the vacuum lines to rebuild the head I noticed a vacuum hose going from the EGR exhaust control P/N 1 277 973 that was not attached to anything - I'm betting that's not right. The end going to the distributor was fine, can you tell me where the other end is supposed to attach to? Thanks.
April 27, 2014
  Followup from the Pelican Staff: The line to the valve should go to a solenoid. Look under the hood at the emission tag, it will list the emission components and a diagram of the connections. - Nick at Pelican Parts  
Joe Comments: This is Joe again. Another thing the car only has 103000 miles and is very well maintained. I inspected the hoses and all look fairly new looking. Dont know if this helps but I really want to get this taken care of.
April 14, 2014
  Followup from the Pelican Staff: Got it, thanks. - Nick at Pelican Parts  
Joe Comments: Hello. I was hoping someone with BMW knowledge can help me with an issue I am having. I have a BMW 528I year 2000 and when I start the car everything is fine. But after about one minute the idle starts to accelerate then go down. it will go up and down in idle for a few minutes only until warm. kinda like a pulsating or just an up and down idle for a few minutes only until warm. it almost feels like when it goes down its kinda choking or getting ready to turn off but at that instant the idle picks back up. after the car is warm nothing happens. Everything is perfect. again first minute is fine after that an up and down idle for few few minutes until warm and then back to just working fine. This only happens in the morning during the first warm up of the day. i was told to clean my idle control valve and I did. I removed it sprayed it good with carb cleaner and still the same. The previous owner i believe used cheaper gas so I put the highest octane from Chevron and didn't do anything. if anyone knows please respond and help me asap. I am selling the car and this is the only hiccup the car has. A mechanic I know thought the possibility of a bad spark plug that doesn't fire right until it gets hot but that dosen't sound right. I am not a mechanic and he is so I don't know what to think. I know basics, and I seen this guy work and he is very knowledgeable. There is no check engine lights but we put an obd reader on there and got the code P0035 - Turbo Charge Bypass/Wastegate valve control circuit High. Any help please. thank you
April 14, 2014
  Followup from the Pelican Staff: The fault code has been displayed incorrectly, as your vehicle does not have a turbocharger. It sounds like your vehicle has a vacuum leak. - Nick at Pelican Parts  
never had a BMW before Comments: I have a BMW W reg 316i Se compact E36 variant it has 134000 miles on the clock the problem is it seems to idle fine then all of a sudden it cuts out with out warning and when attempting to start it again it backfires terribly and refuses to start but if I leave it for a few minutes and start it again it runs fine for a few minutes and then cut out again.
April 13, 2014
  Followup from the Pelican Staff: Could be a faulty crankshaft sensor or fuel pump. I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
coy in Salem OR Comments: My 1989 325i Convertible runs great with 240,000 miles. But, it idles rough - sometimes - not always. The tach barely shudders at about 700 rpms, so it's not like the idle is surging or dropping. It acts like it is rich and slowly loading up. It stumbles when I take off, but if I plant my foot, it clears quickly.

I had it smoke tested and all the rubber is supple and seems pretty new. All of the electrical components test within a very close range to what you noted in your excellent article.

Is it possible that the ICV could test electronically okay, but still malfunction? When I un-plug it at idle, I don't see much difference.

I put 4-5 bottles of fuel drier through thinking it was just bad gas, but the results are inconsistent. How bad is it to put too much of that stuff through your engine at one time?
April 1, 2014
  Followup from the Pelican Staff: Yes, the ICV could be faulty. However, i would assume the rough idle is more a product of the mileage and mechanical engine wear. - Nick at Pelican Parts  
Alan 44 Comments: I have a 91 E30/M42. The check engine light is on and is showing a 1215 code, MAF fault. When cold, has a hard time staying running with out a lot of manual throttle input. When warmed up, it will idle but hesitates badly. If I unplug the sensor it runs better but idles high and still has a bad hesitation. I don't mind buying a new sensor if I know for sure it's bad but how do I diagnose it properly. I have just purchased this car recently with this problem and do not know any of its history.
March 20, 2014
  Followup from the Pelican Staff: You will need to grab a wiring diagram. Then test the reference voltage, ground and signal. Test for idle voltage and peak. - Nick at Pelican Parts  
Chili Dog Comments: Please advise-After reinstalling intake manifold
new starterThe engine runs rough real rough and sounds like backfire in engine compartment, clapping sound too, I don't have vacuum to brakes either. Could I have kinked that Y hose located under the throttle body? The hose to the brake booster does not snake around in the correct position as before. Any thoughts? Thank you for any ideas- before I have to take it apart again.uggh!
March 20, 2014
  Followup from the Pelican Staff: Maybe you left the brake booster hose off? - Nick at Pelican Parts  
DAZA Comments: Thanks Nick, What and where are the idle control components.
February 20, 2014
  Followup from the Pelican Staff: The idle control valve, throttle housing, the associated hoses and lines. - Nick at Pelican Parts  
daza Comments: Hi I have a 1997 build 318i e36. When it idles in neutral or in drive and the ac compressor kicks in, the idle drops low enough so the engine shudders and immediately picks up to proper idle speed. What should I be looking at. Thanks
February 19, 2014
  Followup from the Pelican Staff: The idle control components. The DME may not be able to raise the idle to compensate for the additional load. - Nick at Pelican Parts  
bkingcampbell Comments: I have a 1986 325e. When in neutral idle surges. Does not surge when in gear. There is a gas smell to like it is running rich when setting still. Have change 2 of the 4 coolant sensors, all vac lines. Any suggestions?
February 17, 2014
  Followup from the Pelican Staff: I would check the engine for vacuum leaks. First and best place to look. - Nick at Pelican Parts  
Frustrated Mike Comments: My 2001 325i has had an idle issue for over a year now. My non-BMW mechanic couldn't figure it out either but did determine absolutely not a vacuum leak! Idle issue is intermittent, doesn't matter if engine is hot or cold, but when it acts up, about 50% percent of every complete stop, the idle bounces, sometimes recovers, sometimes stalls if I don't race the rpm's for second. There are no OBD codes. One thing I have noticed after all this time is, the only time the idle issue is not intermittent is if I turn on something electrical such as lights, interior fan, AC etc. RPM's drop slightly and recovers... everytime! So it has me wondering about the electrical system/charging system. I did replace the alternator before this issue with a brand new one because the old one completely went out. It wasn't more then a month or so after that this issue came up.

After reading this Pelican article... it has me determined once again to try to finally solve this issue!! I will go through the above check list, but if anybody could shed light on the possibility of alternator being the culprit... please do!I just have a sneaky feeling it's something I did or touched!
February 6, 2014
  Followup from the Pelican Staff: Keep us posted on what you find. be sure to check for fault codes and especially check the throttle housing. - Nick at Pelican Parts  
Mechsport Comments: I have a 528e 85 with a idle problem . I have checked for vac leeks none found. Replace hoses . Tested idle control valve working put new brake booster in . Put new coolant switch in and sensors . Cold start vale . Have not replaced thermal switch. If I squeeze the hose to the throttle control vale to the boot it slows the idle down . Any suggestions?? Help
January 27, 2014
  Followup from the Pelican Staff: The idle valve may be stuck open or being commanded to that position. I would check the coolant temp sensors and idle switch. If they are OK, the idle control unit may be faulty. - Nick at Pelican Parts  
James1335 Comments: Hi, I have a 1990 318is that won't start at all, though it cranks. For about a week it intermittently started and chocked for about 5 seconds with a very erratic idle like the fuel was cutting, then die. After 5-10 attempts of doing this it would start and run fine again. Originally this was only happening when the car was hot, but got worse and now won't start.

Checked spark, relays and fuses, then replaced fuel pump. Fuel pump runs with distinctive whining sound. Listened to injectors and all sounded like they were firing with a tap tap tap. No dash lights have ever come on with this issue though i have been unable to do the stomp test. I tried multiple times but never got it, could a faulty TPS cause this?

Thanks,
James
January 27, 2014
  Followup from the Pelican Staff: You will need to check fuel pressure and injector pulse using test equipment, not sound. I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
beeMerbOy.SA Comments: Hi guys I have a 84 bmw e30 having a oil leak under at the throttle position sensor what can that be I'm lost?
January 21, 2014
  Followup from the Pelican Staff: Could be oil residue from the intake manifold. You will have to dig in there and see exactly what is leaking. - Nick at Pelican Parts  
Zack Comments: i have a m20b27, can i change the MAP sensor without taking out the housing? I can't find anywhere how you replace just the sensor itself. My idle jumps from 800-2k once its warmed up a little, thanks!
January 13, 2014
  Followup from the Pelican Staff: Not that I am aware of. - Nick at Pelican Parts  
thecrud Comments: I have a 1993 325i The vacuum line for I believe the fuel pressure regulator on the back of the fuel rail just fell off.
Where is the other end of this line and how do I get to the back of the rail. the wire box is in the way.
January 10, 2014
  Followup from the Pelican Staff: I believe it runs down behind the throttle housing. - Nick at Pelican Parts  
thecrud Comments: On the top back of the engine is a small vacuum line back of the fuel rail this line fell off in back of engine the box of wires is in the way how do you get to it put it on with the rail partially off and intake off I could still not reach it
I am glad I did not remove the back fuel line.
January 10, 2014
  Followup from the Pelican Staff: Follow the line to the connection point on the intake manifold, then feed it back int place and connect it. - Nick at Pelican Parts  
tdog Comments: Hi i have an 86 325er and whenever i start it up the first time it idles perfectly at about 800. but then after warming up driving for about 20 minutes the idle will be at 1200 and then drop to about 800. It does that like 3 or 4 times everytime i come to a stop. Its like on and off. could it be a sticky icv?
January 8, 2014
  Followup from the Pelican Staff: This could be a faulty ICV or ICV module. First check the idle switch and coolant sensor. If both are OK, you can try cleaning the ICV before replacing or testing it. - Nick at Pelican Parts  
Josh Comments: 1986 BMW 325e: rough low idle when cold, smoothing out when warm. Intermittently the car will start bogging down and surging, but only if it has been driven very lightly for a while, like in the snow. If I floor it very little happens until I get to ~2200 rpm and then it rockets forward like nothing ever happened and drives perfectly fine for a while, until engine load is light for an extended period of time, it starts to bog, I push it, it's fine for a while etc ...

vacuum leak? clogged fuel filter? fuel pump? afm? Sometimes the car does it and sometimes not. Varies day to day.
January 6, 2014
  Followup from the Pelican Staff: A lot of things can cause this. I would start with some tests. Check fue pressure, volume and quality. Check the engine for vacuum leaks and test exhaust backpressure. - Nick at Pelican Parts  
jonathan Comments: I have two questions. First, "You will notice a vacuum hose attached to the throttle body, this is part of the emission control system." - I cannot locate this by just looking, part number or better description? Second, I can get continuity on the throttle position switch when the throttle is completely closed, I actually have to push it closed to get it, so I am assuming it needs to be adjusted, however what screwdriver or angle do you use to get to it short of removing the intake manifold? Thanks.
January 4, 2014
  Followup from the Pelican Staff: No photo. I would need to know your vehicle info to give you a part number.

I use a small ratcheting screwdriver. Adjust it just enough t get the proper reading at idle. Then check that it reads correctly for open throttle. - Nick at Pelican Parts
 
fauzi Comments: thanks nick I appreciate your response I will definitely check my fuel line, vacuum, and hoeses could the odb hook up lend me some idea if I hooked it up or would it be waste of time to hook it up cause I need a converter since its the odb 1 20 pin hook up? could my fuel pump or fp relay be faulty?
December 17, 2013
  Followup from the Pelican Staff: It's always worth checking for fault codes. However, your check engine should be ON if any are stored. - Nick at Pelican Parts  
fauzi Comments: more insight I recently changed my clutch slave cylinder does the idle slip when this happens?
December 16, 2013
  Followup from the Pelican Staff: No, unlikely. Unless you left something disconnected. - Nick at Pelican Parts  
Fauzi Comments: I have an 88 325i on cold days when I first start up the car runs fine but after it warms up the idle drops too 500 550 and the car begins to not have its moan its more choppy I would just want some insight on how to raise my idle or some of yalls knowledge could it be my feul injectors? when it is choppy when I go above 2500 rpm it usually cuts back to its moan
December 16, 2013
  Followup from the Pelican Staff: You could have a vacuum leak and a fuel delivery problem. It does sounds like two separate problems. I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
Jay Comments: Hi, I have a 94 525i, I just recently changed the clutch on it and it starts idling rough unless i give it a little gas. It seems that once i give it a lot of gas while idling in traffic the jolting goes away but everynow and then the engine sounds likes its going to die and sometimes the engine lights comes on. Last night i was driving and it starts dying on me, It will start back up again but i have to constantly apply gas in order for it to keep running or it will just shuts off.
December 15, 2013
  Followup from the Pelican Staff: Was the problem present before the clutch replacement? You could have a fuel delivery problem or a faulty sensor. I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.


- Nick at Pelican Parts
 
kaisernine Comments: Hi I own a 318i W 2000.The car failed it's mot so I declared SORN.Six months later I finally had the funds to put it through the mot but a couple of problems have arisen in the time it's spent sitting doing nothing.
The car starts up fine but when I press the accelerator there are no revs,it just continues idling.So I tried moving the car off the clutch in 1st gear,when I do this the near side front wing dips and the car won't budge and eventually stalls.I've tried doing the same in reverse and the same thing happens, although without the dip.Any help would be very much appreciated thanks.
December 11, 2013
  Followup from the Pelican Staff: is the check engine light on? if so, I would start there. You could have an issue with the throttle or the fuel delivery system. - Nick at Pelican Parts  
Casbot Comments: I have a 2004 E46 320i. What are the normal idle rpm´s in Park, just sitting there without giving any gas and what is the normal idle rpm´s for when in Drive but sitting at a traffic light?
December 9, 2013
  Followup from the Pelican Staff: It will idle around 750 RPM. maybe a little lower. - Nick at Pelican Parts  
imtight Comments: Hi!

I have a 2001 BMW E46 318i touring. Recently did an engine swap and replaced the M43TUB 1,9 engine with a "new" used one.

The only problem now, is that it idles steady at 1700 rpm. Car runs great in all gears and rpms, but revs up to 1700 as soon as I release the clutch. Fortunately I got plenty of spare parts as to the engine swap, so I've tried switching back and forth on everything. I know for a fact that the air intake from the old engine worked prior to the engine swap, so i'm thinking it's a ECU problem of some sort.

Anyway, Now the car is at a certified BMW workshop for a diagnose. It seems like the people there does not even have a remotely idea of what's troubling my car. I got a phone call and they said all they found was a bad ABS sensor.
December 3, 2013
  Followup from the Pelican Staff: It sounds like there is a vacuum leak or that the idle control solenoid is not communicating with the DME. These types of engine swap problems in modern electronically emission-controlled vehicles are only solved through trial and error. Anyone who has not done EXACTLY your engine swap would likely know where the problem lies. - Nick at Pelican Parts  
hendro Comments: hi nick, I have 318i E30M40 and engine would idle very low @400rpm when starting cold im living in tropical country so temperature never gets below 25 deg celcius

low 400rpm makes the engine shudder and when gas lightly pressed engine seems to bog down for a second then rpm started to raise. when engine is warm everything seems normal idle between 700-900 rpm but still that initial pressing gas cause engine to bog down.

so ... something i can do to cure those low rpm cold idle and engine bog down ?

thanks a million
November 28, 2013
  Followup from the Pelican Staff: I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.

You could have a vacuum leak or a faulty crankcase breather valve. I would check both, inspect the engine for a cracked intake boot, vacuum line or leaking gasket. You can also check the crankcase vacuum, this will help you diagnose the crankcase breather valve.



I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
Jayzzle Comments: Hi, I have a problem that maybe you can help with. When the engine is cold it drives fine, perfect, idles nice and runs smooth, however, when it heats up to normal operating temperature it idles low, 500ish and if you lightly press the accelerator it jumps and jerks and doesn't go anywhere, and if you put your foot hard down it takes ages to build up speed. I have changed plugs and 1 lead that was broken, I changed the fuel filter yesterday also.

The car is an e30 318i touring, m40 engine. Any help would be appreciated. Many thanks.
November 27, 2013
  Followup from the Pelican Staff: I would start by checking your fuel delivery system. If it checks out ok, check exhaust backpressure. - Nick at Pelican Parts  
dbagtbag Comments: Hi,

I've a very healthy E30 325i that I bought with 240k miles. It idles just fine, but sometimes when I come to a stoplight the revs drop to around 500rpm, back up to 800 and down a couple of times, before settling at around 800. I'm not extremely concerned but is this normal? Danke!
November 26, 2013
  Followup from the Pelican Staff: No, the idle should hold steady, maybe a 50 RPM fluctuation. I would check the engine for vacuum leaks. - Nick at Pelican Parts  
Tdog Comments: I have an 86 e30 and when you give it some gas the Rpms would go up but when they drop it seems as if the engine catches itself at like 800rpm. But today I went to start it and it got dramatically worse, when the Rpms drop it goes down to about 400 for a few seconds then slowly makes it's way back up to 800. It's also running rich it smells like a snowmobile when I put it in the garage. Any help would be appreciated. Thanks
November 25, 2013
  Followup from the Pelican Staff: You could have a vacuum leak or a problem with the idle control system. Have you removed the idle control valve from the picture? I would disconnect it and see if the vehicle idles normally. If it does, you may have an issue with valve or the ICU. - Nick at Pelican Parts  
Katie Comments: figured it out, I bent the FPR bracket and it doesn't seat right. Luckily I have a spare fuel rail, derp!
November 25, 2013
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
scottf13 Comments: I unpluged the o2 sensor an no change
November 24, 2013
  Followup from the Pelican Staff: That would have been a lucky guess. We still need to check fuel pressure. Also you can check if the vacuum line leading to the fuel pressure regulator is full of fuel indicated a broken fuel pressure regulator diaphragm. - Kerry at Pelican Parts  
scottf13 Comments: It eats gas and seems like its not getting enough air
November 23, 2013
  Followup from the Pelican Staff: Check your spark plugs, fuel pressure and try unplugging the O2 sensor and see if this helps the car run better. - Kerry at Pelican Parts  
scottf13 Comments: Ive already put on a new mass air flow sensor but yet it still runs rich so i guess have to chamge the o2 sensor but when i unplug the o 2 sensor nothing changes still hesitates and will stall when cold.
November 22, 2013
  Followup from the Pelican Staff: Define rich, how are you determining this? - Nick at Pelican Parts  
Katie Comments: I've got a 1992 325iC e30, m20b25 engine. Recently replaced IM gasket, valve cover gasket & rocker plugs, vacuum hoses, intake boot, crankcase breather hose, injector and FPR o-rings. The engine starts rough-as if I still have vacuum leaks and it will cut out while driving. The gas pedal stops responding, the engine starts misfiring, all the dash lights come on and it shuts off! Then it will immediately fire right up and drive off like nothing ever happened. This started happening right after I replaced the FPR o-ring which I did a week after the injector o-rings because I only bought 12. The car is not throwing any codes yet. Any ideas?
November 22, 2013
  Followup from the Pelican Staff: Check that you don't have a component plugged in the wrong place and that the engine grounds are tight. If they are, I would double check for vacuum leaks, check when the engine is cold. - Nick at Pelican Parts  
scottf13 Comments: How do you get it to run leaner because its running rich
November 21, 2013
  Followup from the Pelican Staff: Well the fuel pressure could be too high. You could measure the voltage on the signal wire. You may have a bad O2 sensor. It could also be the MAF, did you try one already. Make sure the spark plugs are in good shape - Kerry at Pelican Parts  
scottf13 Comments: Hi i have a 1995 bmw 325i it has a rough idle it jumps around it has no power when i give it gas untill it warms up and then still dont preform at driving ability. Ive changed the throttle positioning sensor , ive put new plugs an boots complete oil change new mass airflow sensor. Idk what else it could be. Can you help me please.
November 21, 2013
  Followup from the Pelican Staff: Try spraying carb spray down the air intake. Does the engine run smoother? If yes then the car is lean and needs to run richer. Check the fuel pressure. If it runs worst it is possibly running rich. Make a small vacuum leak and see if the engine runs better. If yes then the engine is running rich and needs to run leaner. Pull the spark plugs and see what color they are. Try unpluging the O2 sensors. - Kerry at Pelican Parts  
krispfh Comments: Hi guys, I have an e30 325i touring with 101k on it, it used to struggle to start but after an oil and plugs change has eased that a bit, it also violently judders under slight or no throttle and has a rough idle, any ideas what could be the culprit? Thanks
November 21, 2013
  Followup from the Pelican Staff: This sounds like a vacuum leak or a misfire. I would start by checking the engine for vacuum leaks. - Nick at Pelican Parts  
chip Comments: Hi, I have a 90,325i and when I put the ac on the rpm go up to 2000 and if I shut yhe ac off it goes back to normal. It doesn't do it all the time. Any help would be appreciated.
November 18, 2013
  Followup from the Pelican Staff: Check your throttle position sensor. If it is faulty, the idle will go higher due to the control modules inability to read proper throttle angle. - Nick at Pelican Parts  
Sohail Comments: hi would like some advice. I have a 91 bmw 325i and when I come to a stand still or stuck in traffic the car will rev up to about 3000 rpm and immediately switch of and refuse to start. any reasons why? thank you
November 9, 2013
  Followup from the Pelican Staff: Sounds like the vehicle either has a large vacuum leak or it is hunting for an idle. Either way you'll want to check the idle motor, if it barely open, there is a vacuum leak. If it it appears to be somewhere in the middle, it may be ok until the problem occurs. - Nick at Pelican Parts  
dram2 Comments: Dear staff, i have a 94 318i e36 m42 every cld start it wants to turn off but is warms up its fine and at time it has a roug idle would you suggest chaging the icv???
October 17, 2013
  Followup from the Pelican Staff: You could have a vacuum leak or a faulty crankcase breather valve. I would check both, inspect the engine for a cracked intake boot, vacuum line or leaking gasket. You can also check the crankcase vacuum, this will help you diagnose the crankcase breather valve. I would also perform a fuel delivery system test. Check fuel pressure, volume and quality.


- Nick at Pelican Parts
 
Tom Comments: Hi Nick,
Quick question. I have an 88 325i convertible, and I disconnected the battery to replace the alternator last week. When I reconnected the next day, the idle bounces between 500-750 every time I stop the car. It does it 5-6 times sometimes 3-4, sometimes 7-8, then evens out and idles perfectly. Running fine, otherwise. Why would resetting the computer do this? Why does it correct, if there was something like a vacuum leak going on?
Thank you!
October 16, 2013
  Followup from the Pelican Staff: With the battery disconnected you cleared all of the adaptation values. I would use a smoke machine and look for vacuum leaks, you will find that it is going to be small.
- Nick at Pelican Parts
 
mtec Comments: Hi, i have a 89 525i the engine idles fine the issue is when you blip the throttle with a short, shallow tap on the gas pedal the rpm drops rapidly and then back up but sometimes it goes down to the point the the engine dies. An suggestions on what it could be?
September 23, 2013
  Followup from the Pelican Staff: There are lots of things to check. Take a look at the air flow meter, the idle valve, the throttle position sensor and the throttle switch, look for a vacuum leak, and check the fuel pressure. Also check the DME for faults.
- Nick at Pelican Parts
 
banta Comments: Hi,I have an '88 318i manual. Had the car out and was running fine. Stopped for a while and when restarted revs went to 3500 and stayed there. If I unplug the ICV the car idles at normal level. Plug it back in and revs back up to 3500. Any suggestions?
September 12, 2013
  Followup from the Pelican Staff: Sounds like the IVC could be stuck open, or the DME cannot control it.
- Nick at Pelican Parts
 
patrick misulu Comments: Hi;I change an engen bmw e36,4 cylinder build in e36 ,6 cylinder body.from the 4 cylinder engen we collected;the electrical loom and computer box now build in a e36,6 cylinders body but the system can't start:any advice out there please?
September 11, 2013
  Followup from the Pelican Staff: By not start do you mean, no cranking at all, or does it crank and not fire.
- Nick at Pelican Parts
 
euro-tech 52 Comments: I have a 1994 325i am having problems with a high rpm ignition breakdown, changed plugs, tps, mass air flow and checked for leaks. cant seem to cure the problem. could you please advise.
September 11, 2013
  Followup from the Pelican Staff: Check the condition of the ignition parts, wires, cap and rotor, ignition coil.
- Nick at Pelican Parts
 
Bill W Comments: Hi. I have a 2007 328i.It runs fine until it heats up,always on a hot day, then it starts to surge.If i took my foot off the brake,it would take off.If i take it out of gear,it stops,until i put it back into gear.It never does this until it get hot.Suggestions please!
August 30, 2013
  Followup from the Pelican Staff:
You could have a vacuum leak or a faulty crankcase breather valve. I would check both, inspect the engine for a cracked intake boot, vacuum line or leaking gasket. You can also check the crankcase vacuum, this will help you diagnose the crankcase breather valve.
- Nick at Pelican Parts
 
Hamani E30 Comments: Hay .. My e30 1990 2.5 .. When i on my A/C the rpm goes to 1500 to 2000 and take a little second and come down .. When i drive a car wi th A/C on have this proplem with rpm its not come down when i stop 2second its come to 1500~ 2000 rpm .. So can u help me and what i do !?
August 29, 2013
  Followup from the Pelican Staff: You could have a vacuum leak or a faulty crankcase breather valve. I would check both, inspect the engine for a cracked intake boot, vacuum line or leaking gasket. You can also check the crankcase vacuum, this will help you diagnose the crankcase breather valve. Also check the function of the throttle switch and the idle motor.

- Nick at Pelican Parts
 
andy Comments: Follow up to Kerry: Thanks but its not the throttle stop screw and there's no locking nut. After further reading I discovered its refered to on this page comment dated 19th May 2013 rply by Nick as 'an adjustable set screw' that some throttle body's have and some don't. Thats the screw I'm refering to in comment below this one. Thanks
August 27, 2013
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
 
andy Comments: Hello mate.... On my 1986 e30 325i I stupidly turned the little screw on the throttle body housing located under throttle spring mechanism but on top of housing becos I thought was idle adjustment..derrr... Anyway Ive been told the little screw is related to the mixture and now the car is sorted I think its running way to rich because getting oil in the large black tube thats attached to throttle body housing. Can you advise on resetting the little screw?
If screwed down all the way how many turns up do you think?
Any advice will help...Thanks
August 27, 2013
  Followup from the Pelican Staff: The little screw is not related to the mixture directly. I suspect you adjusted the throttle stop screw. This screw prevents the throttle butterfly from moving too far back in the throttle bore and binding. It should have possibly an 8 or 10mm lock nut on it. Is that the one? If it is losen the lock nut and back the screw out till it no longer touches the throttle linkage. Turn the screw inward until it barely touches the throttle linkage, then add another 1/4 to 1/2 turn and tighten the lock nut. You may have to check your throttle position sensor or switch adjustment when you are done. - Kerry at Pelican Parts  
Daddi-o Comments: Hello there, I have an 1989 325is manual transmission it has been one of the best cars I have ever owned, engine runs smooth when A/C is on but as soon as you turn it off the idle starts becoming rugh to the point that the engine light comes on and off at times happens whe you are in a complete stop, can you give me an idea what can be happening here I will appreciated it.
August 27, 2013
  Followup from the Pelican Staff: I must admit I am a little baffled! Usually the additional load of turning an AC compressor makes the idle drop or unstable but in your case it is the opposite. When you remove the load of the AC compressor the engine runs poor. I would need to know is the car running rich or lean? Is it surging or loping? Take off the oil cap and see if the engine runs better with the AC off. This would be creating a vacuum leak. If the car runs better then you are running rich. While it's idling spray carb spray down the air intake. If the engine speeds up and runs smooth then you are lean. I hope this helps - Kerry at Pelican Parts  
Bubba Comments: My 89 325i will drive fine, once I turn it off and start it back up while hot and go a little down the road. While stopped at a light, the revs will drop then go back up and drop, and it will over come my breaking and slowly move forward till the revs drop then it will stop, but the check engine light will come on while it happens. And when coasting, or slowing down the check engine will come on and off just a few times, almost like a miss, or the belts are slipping. It's very bothersome, I've only owned this car for 2 months, I love the car so much, but it bothers me cause today it dies at a light, it's automatic... I need help!!
August 26, 2013
  Followup from the Pelican Staff: If you idle is surging you should look for a vacuum leak in the intake manifold. Also check if you have a throttle switch or a throttle position sensor. You may have a bad idle speed motor as will but check for vacuum leaks first. - Kerry at Pelican Parts  
Becky Comments: I'm buying a 1992 BMW 320i from my brother and he tells me that the car is great but everytime he comes to a stop with the car it shuts off on its own. I was wondering if anyone knew why this happened.
August 25, 2013
  Followup from the Pelican Staff: It could be a vacuum leak, a bad throttle posisiton sensor or a bad idle speed motor. I would check those things first - Kerry at Pelican Parts  
Pro_Wino Comments: I have a 1989 325i with a slight idle problem. I'm planning on replacing the vacuum hoses and the air boot. After poking around I found that an elbow piece that connected the breather hose to the valve cover was pretty warn and loose. It's definitely leaking air. For the life of me I can not figure out what the name of this part is as it seems like maybe earlier and later models don't use this piece. Can you point me to what the name of this elbow part is so I can buy it and replace the whole system? I added a photo. Thanks!
August 19, 2013
  Followup from the Pelican Staff: Contact one of our parts specailist at 888 280 7799 and they'll help you get what you need - Kerry at Pelican Parts  
blane031 Comments: Hi there. Im from south africa and I have a 89 e30 318i. M40 motor
I have just rebuilt the eNtire motor, rebore 20 tho. I had a problem with a rough idle and changed the idle valve, seem to sort the problem out but wen I drive car runs smooth and wen I press the accelerator to go faster is starts tp jerk and once I leave the pedal n press again it accelerates proplly. What can b the cause of this?
August 18, 2013
  Followup from the Pelican Staff: It could be the valve timing is not correct, or the throttle position switch/sensor is faulty or you have a worn airflow meter - Kerry at Pelican Parts  
Cesarhdez Comments: Hi. I have an 89 325i. Today I just change the idle control valve and the idle its much better. The only thing is that when the car is stop idle stay at 1000 rpm. How can I calibrate the idle in 700-800 rpm?
The idle has a really small movement, lets say from 1000 rpm to 1050 rpm, is it normal? Or should I suspect some thing is wrong?
Another thing, with this new idle control valve when I open the switch the valve has a small sound, do you know what can be?
Thanks
July 23, 2013
  Followup from the Pelican Staff: Is this a two wire ISC or three wire? The two wire design should have approximately 450ma passing through it so you have to connect an amp meter in series. The three wire ones usually have power on the middle pin and pulse to ground the outer pins. One to open the motor and increase rpm the other to close the motor and decrease rpm. When you say open the switch do you mean the idle position switch in the TPS? You also may have a vacuum leak that can cause the possible lean surge you are describing. - Kerry at Pelican Parts  
Satisfied Customer Comments: I have a 1988 e30 325i in Australia. Drives great upon first start up even when cold but if I warm it up, stop for 10-20 minutes engine off then restart it, it runs very rough for a minute or two then drives fine. The first couple minutes it is undriveable and likely to stall if I try to take off. It very recently had a full service and timing belt + plugs. What could be causing this issue? P.S. I love your workshop guides and the parts even with shipping are about half the price what BMW in Australia is charging.
July 14, 2013
  Followup from the Pelican Staff: Sounds to me like you might have leaking injectors flooding out the engine on a hot restart - Nick at Pelican Parts  
beemerboy Comments: Hi guys please I have a 320i chrome bumper 86 automatic have a misfire wen idling what is the cause of it?
July 10, 2013
  Followup from the Pelican Staff: Try to unplug each injector one at a time (look up the Pelican procedure for removing injector but just unplug it electrically) and make sure the rpm drops equally every time an injector is unplugged. The cylinder that doesn't drop the rpm is the problem cylinder , then check spark, fuel injector pulse and compression- Nick at Pelican Parts  
Rolomiester Comments: Hey guys, first of all, just wanna say, I love your forums, really helpful and informative. Im from South Africa, and theres not alot of support for the older e30s here.

So, I need to know, I have the early model m10 Carb model e30 316, and my idle is also all over the place, around 900-1200 rpm, and this persists into driving as well, in 5th at 3000 i get a bit of jerking, and it seems to run very rich. Worse news is, this week she suddenly decided she doesnt want to idle at all, and will only keep going if i repeatedly give her gas.

The pierburg carb wasnt on the car when I bought it, instead it a vw jetta carb, but cheap pirate, not original.

My question is 2 fold,
1- should I get a weber and if so which size? and 2, what can I do to fix the idle?

I have replaced the timing chain and sprockets, and that theres the usual tappet tap but not too loud and however it seems to be all fine except the idle.

Thanks,
Rolomiester
July 9, 2013
  Followup from the Pelican Staff: You're probably going to need a rebuilt carb. Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
 
MrPig Comments: Follow up to Nick; I fixed a leaky camshaft seal and o-ring as well as replaced inner/outer control arm ball joints and bushings totally unrelated to my oil leak but it had to be done. I don't get an RPM dip in reverse anymore and the engine vibration is not as noticeable. Can't say I can explain it. Haven't driven the car enough to see if the symptoms return.
July 5, 2013
  Followup from the Pelican Staff: A change in vibration may have affected the knock sensor changing the ignition curve - Nick at Pelican Parts  
MrPig Comments: Hey Pelican Parts guys! Love your articles, used your DIYs many times with great success. I have a small issue with my '90 325is. On cold start the car will vibrate, not violently but you can feel really it. The engine RPM doesn't surge at idle or when hitting the gas in gear or neutral and will hold at a steady 900ish until the engine warms up and it drops to 750. If I put her into first and go, everything is fine. If I put her in reverse and start backing up the engine RPM will drop and she'll almost stall. Oil is fresh, plugs are brand new Bosch Platinum +4. Once engine is warm, no vibration or rather normal vibration. If I park and restart the engine a few minutes later while it's still warm, none of the symptoms I described are there. Any advise will be appreciated.
July 4, 2013
  Followup from the Pelican Staff: Normally the idle would be faulty in both first and reverse, unless your technique of using reverse is different. If engine RPM is not steady, check the idle control valve and associated parts. If you can keep the engine running in reverse by opening the throttle a bit more, the idle control valve may be the issue. - Nick at Pelican Parts  
augustine Comments: My 318i 2000 model failing to hit above 120 on rev and hardly starting after hours of park and at times very slow pick up and a bit of shakes when picking up.
June 29, 2013
  Followup from the Pelican Staff: Sounds like an engine misfire. I would start by checking the DME for fault codes. If there is amisfire, fault codes will be stored directing you tot he faulty cylinder. - Nick at Pelican Parts  
Maschine Comments: Changing a fuel filter, the one with the arrow . Located right in front of the driver rear wheel - I drained the tank but most of the fuel came from the "front" of the car, rather than the topside. Am I missing something here or did zee germans decide to snake fuel lines all over the place.

Also, when I move the old filter around I hear clunking. The new one doesn't make a sound. Am I changing something other than a fuel filter. Pictures would be great
June 28, 2013
  Followup from the Pelican Staff: Fuel will drain from the front of the system also, this is normal. 5 gallons is not, I would guess you have the hoses mixed up.

Not sure what would be clunking inside a fuel filter, unless the filter element is detached from the filter. - Nick at Pelican Parts
 
dlalas Comments: My e30 320i '91 model takes several swings before caches 5the idle and the idle isnot stable but up and down between 500 & 1000 rpm, especialy when the engeen is cold, bt when the temperature rises the idling risis to 1300rpm
June 9, 2013
  Followup from the Pelican Staff: if the idle is unstable when cold, this would point to a problem with the idle control valve or circuit. - Nick at Pelican Parts  
bimmerbrooks Comments: Hi. I have an 8/88 325isA auto and I am having a weird idle issue that may or may not be related to the vac system. It started with a coolant leak @ the tranny cooler line inlet on the radiator. I decided to replace the radiator with an all aluminum one and separate the two systems. This worked fine. I replaced all the radiator and heater hoses with silicon to avoid future blowouts. Drained the block, flushed the system and dissolved 2 gaskets. One was the thermostat housing gasket, the other was the throttle body heater gasket. changed them both, caused an electrical fault while coolant dripped on the harness for the injectors and coolant sensors. I replaced the sensors, fixed the short in the harness and changed the oil because some coolant drained down the CC vent hose and gave me some chocolate milk. Now, I am experiencing a ROUGH idle. Steady, but rough. I also have 2 wires going to what I believe is my temp sender gauge brown which is only supposed to have one. Im not sure if this would make a difference. thanks for the advice
June 2, 2013
  Followup from the Pelican Staff: If the engine is only running rough at idle, I would check the engine for vacuum leaks.

Do not worry about the coolant temp sensor wiring. If the wires are routed correctly it should be OK. - Nick at Pelican Parts
 
sam Comments: Does 1987 BMW 325e with 2 kind of Idle control valve regulators or only one version? If it has two versions, please advise how to verify and buy the right parts??
May 19, 2013
  Followup from the Pelican Staff: There is one style but two parts available. One has an adjustable set screw, the other does not.

Give our parts specialists a call at 1-888-280-7799. They can help you find the right part. - Nick at Pelican Parts
 
KC Comments: I have a 91 BMW 318IS with manual tranny. I want to seafoam the engine but don't know which vacuum line/hose to use. Can you tell me which one and where it is on the engine. Thanks
May 2, 2013
  Followup from the Pelican Staff: If cleaning the top of your engine, I would suggest doing it with the engine off. If you introduce too much fluid while the engine is running you can damage the engine by hydrolocking.

To answer your question: The brake booster hose is the largest vacuum line on the engine. - Nick at Pelican Parts
 
ZachG87e Comments: Forgot to put it on last post but my car is a 1987 325.

Thanks!
March 19, 2013
  Followup from the Pelican Staff: Thanks for the vehicle information. - Nick at Pelican Parts  
ZachG87e Comments: I will be doing this but was wondering if you had any ideas as my car started with an idle issue. It would drop to almost dying then bounce back up and slowly work its way down. Now if I take my foot off the throttle the car dies. Should I start with a vac. check, or is there something else more likely to be the culprit?
March 19, 2013
  Followup from the Pelican Staff: Check that your idle valve is operating correctly. There is no idle set screw on the throttle housing, so you will have to look at the electronic idle control system first. - Nick at Pelican Parts  
xxx Comments: sorry i have a 316i bmw 1989 and i have some trouble with the idle control valve .. can the control valve be fixed or you must buy another one .
February 19, 2013
  Followup from the Pelican Staff: I suggest replacing the valve. I have never heard of a successful repair of one. - Nick at Pelican Parts  
Wuth_AK Comments: Great write up. My car was idling at 400-2000 RPMs, just up and down, up and down. I followed your guide and she now idles about 900.

Thanks again!
February 11, 2013
  Followup from the Pelican Staff: Great job and yes this is why we are here. Thanks for the kudos - Nick at Pelican Parts  
TrueBlue Comments: Thank you Jared. A very thorough how to article that will help me replace my vacuum hoses and clean the ICV to improve the idle. I have a 95' 318ic with the M42 4 cyl. engine. According to Bentley, mine does not have the air mass sensor. Are there any procedural changes I should be aware of? Thanks
January 26, 2013
  Followup from the Pelican Staff: No, just follow the procedure and skip over steps that do not directly apply to you. If you do each line one at a time you should not run into any problems. - Nick at Pelican Parts  
Ramesh Comments: Hi , I need help! I got a car that just won’t come right. The problem is - it starts but won’t go above 2000 revs, I checked the timing 6 times already & its 100% but still won’t come right. The head have been to the engineers N all valves are ok, pls someone who had this problem pls let me know the outcome Thanks
November 15, 2012
  Followup from the Pelican Staff: There are many causes to this problem that may not be engine related. One of them is to make sure the idle switch is not stuck closed. The computer will not let the engine rev past 2000 with the idle switch closed. - Nick at Pelican Parts  
has14 Comments: I have bmw auto320d 2001 I have a probkem with my engine cut off as soon as i slow down ay a stop i have checked all I still can't find the fault
October 2, 2012
  Followup from the Pelican Staff: Is this a diesel? If you decelerate in neutral does the engine still stall. Sounds like you have an idle control problem. - Nick at Pelican Parts  
mike Comments: i have a 1987 bmw 325e and motor idles high all the time does anyone know what would cause it to do that? i've checked everything so far and i still haven't figured it out. my dad has a code reader but he don't have the right plug to hook it up to my car cause it takes a round plug.
September 28, 2012
  Followup from the Pelican Staff: You could have a bad idle switch/TPS, a bad idle speed motor/wiring or a vacuum leak. - Nick at Pelican Parts  
E30lover Comments: mabe i can get help from u guys. got a 323i e30 that i cant get to run properly. the oil sump keeps filling up with fuel when i try and start it. fitted new fuel pump,new fuel relay,new plugs,changed engine loom,diffrent computer box and it stays the same. pls help
September 10, 2012
  Followup from the Pelican Staff: Check to see if your fuel pressure regulator is leaking fuel into the intake and it is washing down your cylinder and getting into the crankcase. - Nick at Pelican Parts  
501scs53 Comments: i have a 92 bmw e30 convtible ran fine then at a stop sign started acting up no smoke no wird noise limped it home sounds like a head gasket no blow by or oil in water or vice versa valve cover off all looks fine did compression test #1 and 100lbs #2 and 4 250lbs will do another comp test starts and runs step on gas hesitates and spits and sputters help
August 8, 2012
  Followup from the Pelican Staff: Sounds like your compression gauge is off. 175 is good for a normal cylinder. So it looks like you have 1 bad (100psi) cylinder. Unplug each injector one at a time and make sure the rpm drops with each injector unplugged - Nick at Pelican Parts  
magic Comments: hi i have 1992 bmw 1992
when i start trh take to the 3 cranking
and then after the engine keep shake slike a misefiring problem i change all spark plugs check all ignition coils are good adn the i cant ger a hight rpm no more than 3000 rpm
please help me to find what s problem
August 4, 2012
  Followup from the Pelican Staff: Check compression for each cylinder and while it is running unplug each injector one at a time. The engine should drop rpm each time to unplug an injector connector - Nick at Pelican Parts  
bsorrels Comments: I fixed the surging idle on my 86 325e for about a dime.
I just put a resistor in series with the coolant temperature
sensor. I used a 1000 ohm potentiometer and adjusted it out. I think it should be a 560 or 680 ohm 1/2 watt fixed.
I thought this was a gerry-rig until I found where somebody
had a broken resistor under the boot for the connector on
a six series. Research showed this was factory installed
in some BMW's. It is hidden.
I think it is to compensate for a different fuel than the
computer was designed around. It will fool the computer to
enrich the mixture slightly for a cooler engine.
July 18, 2012
  Followup from the Pelican Staff: It does change the fuel injection curve according to temperature. More resistance means a slightly colder engine - Nick at Pelican Parts  
general sayah Comments: My BMW 320i 2002 is showing an EML sign which i do not understand what it means.After showing the sign it can only do 80km/hr and wont go any further like its powerless even if the accelerator pedal is pressed fully. computer diagnosis reads engine throttle output shuts off after diagn.error, all the sensors are said to be ok and i rilly do not know wat it is then.
June 14, 2012
  Followup from the Pelican Staff: This means you have a problem with the electronic throttle. Have the code cleared and see if everything goes back to normal. You can try disconnecting the battery and see if that resets it. You are going to lose your radio station presets. Also when reconnecting the battery turn the ignition on for at least 90 seconds to reset the throttle adaptation. - Kerry at Pelican Parts  
hulk Comments: hey guys i know this is not relevant to the subject at hand. BUt i wanted to ask "CRAPPYE30 AND DavidsFast_e30". What head lights those r.. i really like them...if either one of you could tell me it would greatly appreciated. my email is mcorrea296@gmail.com..thanks guys
May 27, 2012
  Followup from the Pelican Staff: I've posted your request in a forum and hopefully some one can answer your request - Kerry at Pelican Parts  
Big Amp Comments: My 03' BMW 325i will not idle. it's not surging but starts and shuts off if I don't press the accelerator. Scanned it and it shows a mis-fire code. Could this be the ICV and if so where is it located? Need help!!!!!!!
May 25, 2012
  Followup from the Pelican Staff: Find the source of the misfire first as that can damage your engine. Fix that and you will probably take care of your other problems. Most BMWs miss because they are running too lean but without much to go on I'm just guessing. What is an ICV? Intake Control Valve? - Kerry at Pelican Parts  
Gregory Comments: Hi can anyone tell me if a bad CCV would make my E39 idle up and down? i have checked everything from hoses and intake manifold and gaskets, my cam is still idling up and down and i dont know what esle to check.
May 20, 2012
  Followup from the Pelican Staff: Yes if the diaphragm is ruptured it is an internal vacuum leak which can cause surging at idle. Any kind of vacuum leak can cause an idle surge as well - Kerry at Pelican Parts  
tractormanjames Comments: My e30 idles normally and runs perfectly , however the tach is all over the place up down . not in sync
May 19, 2012
  Followup from the Pelican Staff: Sounds like you have a bad tach. Check the wiring connections for the cluster and the coil. You may just have a bad tach - Kerry at Pelican Parts  
Justin Comments: Hello,

I have a 84 e30 with the inline 6. The car raises idle from 800 rpms to 2000 repeatedly for as long as the car is running. I have changed all vacuum hoses, checked the idle motor, changed the idle module, changed the intake gaskets, and checked the intake for any cracks. I have no clue whats left. I figure it could be those sensors in the bell housing but i dont know. This issue has been happening for about two years and started when i turned a corner. Please advise.
May 9, 2012
  Followup from the Pelican Staff: Well that will teach you not to turn a corner. Try checking the idle contact switch. This is on your throttle body. One wire switches with the car at idle and the other switches at close to wide open throttle. With a bad idle switch the module does not know you are off the throttle and want the car to idle. - Kerry at Pelican Parts  
Gregory Comments: i have a 2000 BMW 525i idling up and down, so i change all of vaccumm hoses and changed the air control valve and the air adjuster, intake manifold seals, throttle body seal,and still idling up and downand when i unplug the air control valve it idles good,what can i check now, i was thinking to change the throttle body? what do you think?
April 8, 2012
  Followup from the Pelican Staff: I would check if the intake manifold runner DISA valve is faulty. I have seen them cause idle issues. It sounds likes you covered everything else. - Nick at Pelican Parts  
BeemerGuy 325is Comments: Hi I have a 1993 325is M50 engine and I noticed oil seeping into the breather hoses from where the valve cover is and intake swallows an amount of oil into it. What causes this and what requires to fix the problem. PLEASE HELP OUT ON THIS PROBLEM! : I am not sure if I am the only one with this issue
March 20, 2012
  Followup from the Pelican Staff: Please check out the Pelican Parts guide to engine problems:
http://www.pelicanparts.com/bmw/techarticles/Borrowed/mult_engine_rebuild-1.htm
-Nick
 
John-Allen Comments: Hey guys - my car was idling up and down pretty badly for a while...it was fine while in gear, but while coasting it would idle up and down between 1500-2200 rpms until the car was stopped. As soon as it stopped the idle would begin to settle down. Changing out the idle control valve fixed this problem and my car is much happier now.

For the guy with the cold start problem, I have the same problem. I can't be certain I've fixed it, but I think I did we'll see tomorrow morning. Check your MAF sensor, and make sure your car has the right one installed for your model. I have a 325i, but it had a MAF for a 325e installed on it, and I think that might've been causing the problem. I have no idea how it was even able to run!

The MAF is right after the air box, attached directly to it. It is black and says BOSCH. The part number is printed on the top of the part and is easy to locate. For a 325i should end in 082 0 280 202 082, and for a 325e it should end in 091. If you have the wrong one installed, which is an easy mistake to make since they look IDENTICAL, that could be causing your cold-start problems. I'll update & let you know for sure tomorrow.

I've put a picture on here, showing what the MAF looks like...
February 18, 2012
  Followup from the Pelican Staff: Thanks for the additional Info. We appreciate it.
- Nick at Pelican Parts
 
stone Comments: I have bmw e30 ,3series and de air flow meter is worry i have change it but is still worry me , where can i get new one to buy.
February 17, 2012
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you find the right MAF sensor.
- Nick at Pelican Parts
 
whome5972 Comments: I tried spraying inside of ICV with little inprovement.Then I soaked overnight in fuel injector cleaner using a narrow jar so it would stand up filled it to level where it would cover the valve and not the solenoid.Has worked much better for now anyway no surging.
February 16, 2012
  Followup from the Pelican Staff: Thanks for the helpful info.- Nick at Pelican Parts  
rote Comments: i have a 1998 318i it will stall out in park i did plugs wires, new idle air control valve, new air filter, new thermostat, and ran injector through the gas but it still stalls out. it runs a lot better but still stalls. any ideas will be very helpful.
February 15, 2012
  Followup from the Pelican Staff: Are there any fault codes stored? I have sen camshaft position sensors cause stalling problems. - Nick at Pelican Parts  
eric the red Comments: I have a 1988 E30 318i the car idles ok but stutters on setting off reulting in me having to slip the clutch, any ideas
February 10, 2012
  Followup from the Pelican Staff: This could be a bad MAF sensor or TPS sensor or a fuel delivery problem. - Nick at Pelican Parts  
james Comments: I own a 1986 bmw 325e, upon cold start the engine turns over for 2-3 seconds and then fires slowly,then idles and runs perfect. cold starts only. Had new fuel pump and new spark plugs installed, no different.
February 9, 2012
  Followup from the Pelican Staff: This could be a faulty cold start injector or a vacuum leak. - Nick at Pelican Parts  
cknyno1 Comments: just bought an 1990 e30 when i take it up over 3000revs its like its starvin for fuel any ideas
February 3, 2012
  Followup from the Pelican Staff: I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
kerosene Comments: the temp sensor was not the problem. finally took car to shop. it was the ECU. runs like new again. wish I had fixed it and saved 200 bucks shop time. The mechanic got a used one from the local BMW wrecker for 195 I was afraid the part would be way more.

January 25, 2012
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
MARK Comments: does some1 no anything about airflow meter? i have a bmw 92 525i and my friend told me to change it as when i went to strt cat car a big loud sound boof from front bonnet appeared with alot of smoke coming out and i have changed it!!! but i just dosent idle as the same before,revs up and down, muffler makes pop,opo,opo sound,clicking sound in engine!!! my friend recons they gave me the wrong 1? bout it has the same serial # 0280213011 product num# 1730074 but the top nums a dif? original 265 20 3 A da 1 i replaced with is different!!!! but maybe its just the hoses, what do u fnk? confused much. MARK
January 25, 2012
  Followup from the Pelican Staff: I would start by installing the correct mass air flow sensor. If you have the wrong one installed, it will create a drivability problem. - Nick at Pelican Parts  
kerosene Comments: might be dieseling. a sign of fouled plugs. but on such a sophisticated machine i suspect a wiring fault. what do you do to get it to stop running?
January 23, 2012
  Followup from the Pelican Staff: It looks like the root cause of your problem was the ECU. I am posting this here from your follow up reponse. - Nick at Pelican Parts  
anwa Comments: hi i have a bmw 328 e36 when i turn key off car keeps on running
January 22, 2012
  Followup from the Pelican Staff: Sounds like the ignition switch (electrical portion) is faulty. Or there is a component backfeeding voltage. - Nick at Pelican Parts  
kerosene Comments: I think I have fixed it. Just about to go to the shop but first I changed fuel filter to eliminate one more possibility. Didn't help but I have a new fuel filter. When I started the car the check engine light gave 3 distinct flashes which is the code for coolant temperature sensor. I had already checked that doodad and the ohmage was good so I jumped a 5K resistor into the pins and the car ran without surging, loping, revving whatever we want to call it. I will buy new sensor and report next week. Don't need the kerosene after all.
January 8, 2012
  Followup from the Pelican Staff: It looks like the root cause of your problem was the ECU. I am posting this here from your follow up reponse. - Nick at Pelican Parts  
kerosene Comments: i see a number of people. me included. have replaced the idle control valve. i pulled the old one apart. it was working perfectly. the part is a very simple rotational senoloid. if the resistance readings are within range-40 outside 20 inside just squirt some wd40 in it and away you go. it seems like the ideal part to replace if the idle is loopy but it isn't. save your money.
December 31, 2011
  Followup from the Pelican Staff: It looks like the root cause of your problem was the ECU. I am posting this here from your follow up reponse. - Nick at Pelican Parts  
kerosene Comments: Went to the electronics store and bought a variable resistor pot. Made a little cardboard box tool so I could dial between 3K ohm and 5K ohm. Jumped this into the circuit to try to fool the ecu that a steady signal was coming from luftmassenmesser AMM still loping idle but ran nicely with the icv disconnected.
I see a couple of others have had this problem. Are you guys still reading? How did you fix it?
December 31, 2011
  Followup from the Pelican Staff: It looks like the root cause of your problem was the ECU. I am posting this here from your follow up reponse. - Nick at Pelican Parts  
greg Comments: i have a 2000 525i BMW and its idling up and down, i changed the air control valve, but that didnt make a different! when i disconnect the air control valve it idles well but wont excelerate, but idles well, and when i connect it back it idle up and down, what do i need to check?
December 31, 2011
  Followup from the Pelican Staff: I would check the DISA valve in the intake manifold. I have seen these cause idle problems. - Nick at Pelican Parts  
Greg Comments: in my 2000 525i, when i connect my air control valve it idles up and down when i disconnect it, it idles well, what can be the cause ?
December 30, 2011
  Followup from the Pelican Staff: The DISA valve could be faulty. - Nick at Pelican Parts  
kerosene Comments: all of a sudden the car started to surge in idle. Just started up and surged away. drove home, read the article, and replaced hoses, boot etc. Did the meter tests on throttle for position OK. Tested idle control 20ohms /40 ohms just like you said OK. Tested air mass meter and its ohmage changed like the manual said it would. started up and still got surging CANT STAND IT ! 1000 to 1500 about 2 times per second. Kicking throttle does not help. The car is an 87 325i with motronic 1.1. Oh if I disconnect the idle control valve the surging really settles down. some of the connections are crimp on bands from factory and they seem a bit loose. Next task is to cinch them up. I'm thinking maybe a quart of kerosene and a match.
December 28, 2011
  Followup from the Pelican Staff: have you checked for vacuum leaks? - Nick at Pelican Parts  
ecsk Comments: Hi,Hornblower
Can you point me to where to download that instruction. Most likely I need to do the same check.
December 22, 2011
  Followup from the Pelican Staff: I think he meant the instructions here. - Wayne at Pelican Parts  
Hornblower Comments: My daughter started experiencing idle problem on my E30 1089 325i BMW. After downloading your instructions and performing resistance checks on the three terminals I received readings of 4 and 23 ohms between the outer terminals. Based on your article I should have received 40 ohms. I removed the ICV and notices that the valve was stuck in closed position. Using a screwdriver I rotated it to open position and cleaned it with carb cleaner. Resistance reading now is around 40 ohms and roughtly 20 ohms between them. That fixed the ICV and car now running smooth. Recommend change in your instructions to check for sticking valve before replacement.
December 21, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
chas10959 Comments: hi all i got a 1992 bmw 318i will start an idle find but under throttle it seems to be labouring at first until the rev's get up a bit,like as if the timing is out but check the timing and compression, all ok, any ideas on what the problem is ????
December 15, 2011
  Followup from the Pelican Staff: Could be a bad fuel pump. I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
ConnorWolf Comments: Thanks for this, I found some cracked vacuum lines... but I also found that the guy I bought the car from must have put the intake together in the dark... regardless it idles great now! xD
December 15, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
jbirkey Comments: Good write up, thank you. I've found your site to be very useful for troubleshooting issues with my '90 316i following my head replacement a week ago. It gave me quite a few good ideas and have been pretty sucessful in fixing my problems. When I first assembled, I neglected to hook up the small hose under the intake boot near the throttle body and it refused to idle all. Now I have the irratic idle as well which fluctuates between 1800 and 800 depending on the temp of the engine. It is leaking oil from the valve cover due to two striped out holes on the top of the head. Plan to helicoil them in hopes that my idle will return to normal.
November 21, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
david_69 Comments: hi all i got a 1986 bmw 318i will start n idle but under throttle it seems to be labouring like as if the timing is out any ideas on what the problem would be? and can any1 tell me where number 1-4 on the distrubor cap is as i think somewhere along the line ive put the leads on the wrong plug cheers
November 20, 2011
  Followup from the Pelican Staff: The firing order is 1-3-4-2. You can use that and line up the rotor to cylinder 1 to check the wires. This is a good place to start if you suspect they are wrong. - Nick at Pelican Parts  
heber Comments: hello guys... i have a 1991 bmw 318i, i have the problem on the ignition when engine cold. i do start under low rpm´s around 600 and hesitates. it does not rev up when cold till reduce the rpm´s while getting warm. any thoughts or comments to solve this issue_
November 6, 2011
  Followup from the Pelican Staff: Could be a faulty mass air flow sensor or fuel pump. Start by performing a fuel delivery system test. Check fuel pressure, volume and quality. - Nick at Pelican Parts  
irishste Comments: i have a 2000 328ci and it seems to jump/vibrate when u go over 3000 revs past 3rd gear dosentr jump in 1st or 2nd!! its only when i depress the pedal fully i can drive on little throttle and its fine any ideas??
October 31, 2011
  Followup from the Pelican Staff: Sounds like and engine misfire. i would check the DME for fault codes. There may be one stored that will direct you to the cylinder. Once you isolate the cylinder, try swapping an ignition coil and seeing the problem follows the coil position. if so, replace the coil. - Nick at Pelican Parts  
big d Comments: 89 325i engine idle speed surges up and down. hesitates on excelleration. cant seem to find fault. Do you have any reccomendations.
October 19, 2011
  Followup from the Pelican Staff: Start by checking the engine for vacuum leaks. This is is the #1 idle problem cause. - Nick at Pelican Parts  
Erwing Comments: HI,

To begin with, my car is a 1987 bmw 325 e30. I have a unstable idle problem, idle at 900 RPM then go to 1800 RPM, then goes back to 900 RPM.
Next, I replaced the TPS, nothing change, the idling problem is still there.
After, I decided to change my ICV, removed the old one from the car, shake a little bit, and found out weird metal sound clicking loose part. I replaced to a used, seller told me it was working fine before removal. I shaked my new part, no sound,no loose part of my ICV. I installed it in my BMW, and not resolved my Idling problem.
Could you sugegst me any thing that could be wrong? loose cylindeer head? Cold start valve?????
September 14, 2011
  Followup from the Pelican Staff: Start by checking the engine for vacuum leaks. This is is the #1 idle problem cause. - Nick at Pelican Parts  
Anton Comments: I have a 1994 318is. I cant seem to find the o2 sensor for the exhaust. car idiling high when cold2500 then drops down to 1500. when driving it searches for the idiling and eventually rests on aboyt 1500rpm.

Could someone please assist?

September 14, 2011
  Followup from the Pelican Staff: The o2 sensor is mounted in the exhaust pipe, below the exhaust manifold. Might be easier to see if from beneath the vehicle. - Nick at Pelican Parts  
dan Comments: I really need help on my 02 325xi. I try to change air filter and thought it would be cool to get rid of the old factory air box system by putting a cone on it. When i try to start the car started and die, so i put back stock housing it did the same with check engine lite on saying it was the P0102 it was the maf low input. Then i let it sit for 2 hours and it started right away so i order the maf thinking it was faulty. Yesterday got home from work and park my car on my driveway for 2 hours then i was getting ready to go to store it started and die, so i thought it would be the maf sensor. Order online and install it. nothing change I let it sit for an hour or so then it started right away, now i am scare to get stuck and anyone help. I will replace the filter hose and see what happen.
September 8, 2011
  Followup from the Pelican Staff: Sounds like you had a mad mass air flow sensor or a bad connection to it. if the vehicle is running OK now and there is no fault code, not much you can do. - Nick at Pelican Parts  
pat Comments: My car is running sluggish. How do I know if it is camshaft sensor, or the vacuum lines? Can I just clean the camshaft sensors or do I have to replace them? If replace, what should the cost be to replace both camshaft sensors?
September 5, 2011
  Followup from the Pelican Staff: If it is sluggish, it could be the mass air flow sensor or the fuel pump. Start by performing a fuel delivery system test. Check fuel pressure, volume and quality.
- Nick at Pelican Parts
 
pat Comments: My car is sluggish on take off. Can it be vacuum lines?
September 5, 2011
  Followup from the Pelican Staff: If it was a major vacuum leak, yes. - Nick at Pelican Parts  
mory Comments: idle control valve is not properly adjusted or may be broken the noise i need more info on that
August 26, 2011
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
mory Comments: this is my comment to this comment mahaff Comments: i have a 1990 318i e30 4 cyl.when cold the idle is rough .when warm it is perfect .also i have a buzzing sound coming from around the glove box area .this is intermittent .any ideas
August 10, 2011



August 26, 2011
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
mory Comments: why dont you check your idle control vavle mostly it needs to be rplaced and also check ur fule pumps the outer one and in take one the take takes about 10 mins to work with aand the outer takes about 20 just check those two things and let me know
August 26, 2011
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
mory Comments: this comment is towards geminirand Comments: hey i have a 89 325is 5 speed and when i start the car in the mornings it idle sbout 2000 rpm then drops to 800 and stays there.. but while it idleing the car just wants to shut off.. but it dont then it kiks back up real fast to about 1200 rpm the goes back down to 800 rpm.it does that ever few seconds. then when i take off 2200 rpm the car wants to shut of then it kiks back up untill i reach 400 rpm and it does it again like it shut off then it kik up..this car have everthing ner timmin belt an water pump wires plugs dis. cap rotor i mean everting a full tune up hoses upper head/ cam lol the hole 9. the car is new. please can u help me out thats the only thing wrong with this car.
August 26, 2011
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
mahaff Comments: i have a 1990 318i e30 4 cyl.when cold the idle is rough .when warm it is perfect .also i have a buzzing sound coming from around the glove box area .this is intermittent .any ideas
August 10, 2011
  Followup from the Pelican Staff: The buzzing sounds could be a faulty ICM (ignition control module) Locate the sound of the bussing, if it is the ICM, replace it. - Nick at Pelican Parts  
Biarritz64 Comments: Hi,
In the process of selling my moms 90 325i, and just trying to work out the last bug.
It idles solid at 900, but when the Ac gets kicked on, it jumps to nearly 2000, settling down to 1300-1500.
Is that normal?
It's just that at times while driving in traffic i'll put the clutch in and it will go past 2000rpm.
Again, she idles perfectly at 900, and i know they are designed to kick up a bit when the ac is on, but it just seems to be too much.
Any ideas?
Thank you, and thank you for making so many little bits and pieces available at such reasonable prices and lightning fast shipping!!

August 4, 2011
  Followup from the Pelican Staff: I would check the TPS sensor. I have seen them cause weird issues when the A/C is turned on. - Nick at Pelican Parts  
geminirand Comments: hey i have a 89 325is 5 speed and when i start the car in the mornings it idle sbout 2000 rpm then drops to 800 and stays there.. but while it idleing the car just wants to shut off.. but it dont then it kiks back up real fast to about 1200 rpm the goes back down to 800 rpm.it does that ever few seconds. then when i take off 2200 rpm the car wants to shut of then it kiks back up untill i reach 400 rpm and it does it again like it shut off then it kik up..this car have everthing ner timmin belt an water pump wires plugs dis. cap rotor i mean everting a full tune up hoses upper head/ cam lol the hole 9. the car is new. please can u help me out thats the only thing wrong with this car.
August 4, 2011
  Followup from the Pelican Staff: Mory offered some insight on your problem:

idle control valve is not properly adjusted or may be broken the noise i need more info on that
8/26/2011 mory

this is my comment to this comment mahaff Comments: i have a 1990 318i e30 4 cyl.when cold the idle is rough .when warm it is perfect .also i have a buzzing sound coming from around the glove box area .this is intermittent .any ideas August 10, 2011
8/26/2011 mory

why dont you check your idle control vavle mostly it needs to be rplaced and also check ur fule pumps the outer one and in take one the take takes about 10 mins to work with aand the outer takes about 20 just check those two things and let me know
- Nick at Pelican Parts
 
Adele Comments: Hi Wayne :

I have a 1989 320i e30 with the M20B20 motor.
Having a major problem with the idle at the moment, have got it booked in to get a full diagnostic done $150, which isn't too bad I guess
Its only been doing it for a few months now.
When idling it is sitting around 600-700rpm which I think is the normal rev count for an e30? However, as I put my foot on the brake when coming to a stop the car almost feels as though it is stil accelerating as I'm depressing the brakes. After coming to a complete stop, it starts to drop down intermittently in revs, and the whole car shakes as it does this. I can hear the car spluttering and it almost sounds as though it has a rotary motor in it thats the best way to describe the noise it makes when revving.
Sometimes it is worse than usual, if I let the car warm up properly before driving it seems to help but the problem is still there.
A few times now the engine has shut off as the revs have dropped too low. It nearly always starts again but as I drive to work daily in rush hour traffic it stresses me out to the max worrying that it may not start again.
The car is pre owned and has had so much work done to it that its frustrating to find I have yet another problem with it.
Some recent work done : new injectors, new ignition coil, new spark plugs, new ignition lead only one replaced- the lead that goes to dizzy cap had rotted out, new 02 sensor.
The air flow meter was replaced roughly over a year ago however due to financial problems I had to purchase a second hand one.
If you could please give me any sort of idea before I go to see this guy and he starts quoting me all sorts of work needed, that would be great.

Thank you very much! Also sorry for the HUGE post :
Adele
July 17, 2011
  Followup from the Pelican Staff: A few things. I would first check the throttle is adjusted correctly. if it is, the problem may be with an idle control component, which is quite common. - Nick at Pelican Parts  
Augg Comments: Hi, I have a 2000 BMW 328i, which idles rough when cold. RPMs decrease momentarily to about 600 and then return to normal. Sometime the rpms decrease low enough that the engine shuts off. Interestingly enough, the engine idles fine when it's hot. Could it be the spark plug coils?
June 3, 2011
  Followup from the Pelican Staff: The coils could cause a misfire, but usually don't get better with heat. I would inspect the crankcase breather valve and the DISA valve. - Nick at Pelican Parts  
Jester Comments: Hi Wayne - I had the comment from february 3rd 2011 - I fixed my erratic idle problem, 1 in a 1000 type problem, the mass air flow sensor box shat it self it seems, I went to Eurotune at miami in Queensland they helped me out by providing the replacement parts needed. Your advice was sufficient, if i had to recommend anything from my experience it would be to thoroughly go over the whole engine for leaks like u said and sometimes go with your instincts as i thought it was the mass air flow box the whole time . . ha ha . . most back yard mechanics don't have suffienct diagnostics tocheck for this problem so one other recommendation would probably to seek professional advice if its cheap enough.
May 9, 2011
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Krony Comments: I have an 1986 BMW 325e and at times it won't start. It is definetly not getting fuel when that happens. I can wait 5 minutes and it starts. The car never quits when you are driving or idling. It just doesn't start sometime. Any suggestions on what to check first?
April 24, 2011
  Followup from the Pelican Staff: I would perform a fuel delivery system test. Check fuel pressure, volume and quality.
Once you confirm there is no fuel pressure, test the fuel pump electrical circuit. - Nick at Pelican Parts
 
BMW4EVA Comments: Bmw 1984 e30 standard. Almost the same as the guy below me. My car turns on and immedialty hits 2k RPMS then quickly its back down at a steady 1k RPMS while idling. Now when I drive for a while at a high speed. I will put it in neutral then it will idle between 1.5k RPMS and 2.2k RPMS and it will take VERY LONG for it to go back down to a steady 1k RPMS while idling.
April 21, 2011
  Followup from the Pelican Staff: Sounds like a faulty idle control valve or ICU. If you disconnect the idle control valve, does the vehicle idle normally? - Nick at Pelican Parts  
Sal Comments: I have 1984 bmw 325e standard. In order to pass smog I must get the rpms at a steady 1k. As soon as I turn the car on it quickly revs up to about 2k Rpms or over, then within seconds it goes down to around 1.5k RPMS and never drops down to a steady 1k. Usually after driving over 35 mph, then idling it will climb from 1.5k to 2k Rpms and back down to 1.5k and 2k and repeat for a while until it has cooled. How can I repair this? THANKS, ANY HELP WOULD BE APPRECIATED
April 20, 2011
  Followup from the Pelican Staff: Does the car idle smooth with the idle control valve disconnected? This could help lead you to a possible bad valve if it does. - Nick at Pelican Parts  
norcal_baller Comments: I have a 92 325is e36 and i drove it the other day and it almost sounds like a Harley. I replaced fuel pump and battery. When the car is cold it starts up ok, but when car is warm it wont hardly start at all unless it cools down, and when I am at a stop light it will idle between 700 to a 1000. when you first press the gas it sputters until it hits 2k then the car is great. i have no check engine light on at all? should i still run the stomp test?
April 15, 2011
  Followup from the Pelican Staff: Yes, your car will tell you what is wrong with it if a sensor is not giving out the proper signals. Take a look at my article on reading fuel injection fault codes in the tech articles section, and that should give you a good clue where to start. - Wayne at Pelican Parts  
stij Comments: I have a 1988 325i that will start but the idle is all over the place, if i rev the engine sometimes the idle levels out at about 2000 but after a few moments it goes crazy again, also if its in gear and i press the gas the car dies, once this happens it wont start again unless boosted or left alone for hours and my battery isnt holding a charge so i have to boost it either way, when i try and start it nothing happens i mean nothing no click doesnt turn over no noise or action of any kind except all the electronics inside the car seem to turn on fine i can only assume i have i have bigger problems than whats discussed here, im going to try everything here anyway but any more help or ideas would save my life
p.s starter and altenator are new its over heated a few times since then once pretty badly so ive replaced the water pump aswell, dont know if that affects anything
April 10, 2011
  Followup from the Pelican Staff: You're right - these are a lot of problems to try to diagnose over the Internet. Thinking about this however, I would double-check to make sure your ground strap is properly connected. Not having a proper ground can sometimes cause all sorts of problems like these. - Wayne at Pelican Parts  
knappjd1 Comments: yes, i have an 86 325e that has a low rough idle when warm. upon reaching normal opperating temps and the vehicle comes to an idle it tends to dip below 500 rpms sometimes as low as what seems like 300rpm. occasionally it dies but usually is fine once throttle is applied. i am eager to try the above suggestions and will respond with the results
April 9, 2011
  Followup from the Pelican Staff: This is a classic sign of a vacuum leak. The injection system may be letting in air when warm that affects the proper metering of the system. When the car heats up, the rubber in the boots and hoses expands, and can create big leaks out of little ones that are there when the car is normally cold. - Wayne at Pelican Parts  
Big Murph Comments: I have a 91 bmw e30 325i. every time i go to start my car it hesitates for about 3 seconds then fires over. once it starts it surges through the rpms but then levels out and its fine. I have changed the distributor cap and rotor, plugs, o2 sensor, vacuum leak, and nothing has fixed it. please help me?
March 31, 2011
  Followup from the Pelican Staff: The first thing I would do is check for vacuum leaks - hard starting can be caused by them. You might want to smoke test the car: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm - Wayne at Pelican Parts  
big_tiger Comments: I have a 87 325 e30, and I went to test the Idle air control valve, but my IACV only has two wires??? I did some searching and see pictures of a two wire IACV, but no where how to test it. I checked resistance on the two leads, and got 10 ohms.

Again my car is a 87 325 with a 2.7l motor.
March 31, 2011
  Followup from the Pelican Staff: If the control valve only has two wires, then I'm guessing is a coil that is either on/off, or uses a variable amount of voltage to control the valve. I can't recall off the top of my head seeing a two-wire one in recent years. I would apply 12V to the wires and see if the valve closes. If you can vary the voltage too, that would be great, then you can test the coil at lower voltage and see if it only opens part-way. - Wayne at Pelican Parts  
bimmark Comments: I have a 1991 318i m42. Starts and idles great from cold. When I try to start it after its been warmed up it idles irraticly and dies if I dont give it gas. Eventually the idle corrects and it drives just fine with no issues. i have replaced multiple vacuum hoses and cleaned the icv. Tested the icv and get 10 ohms between the two terminals. My icv only has 2 terminals. Is my icv bad? If I unplug it what should happen? Thanks.
March 23, 2011
  Followup from the Pelican Staff: It's difficult to diagnose something like this over the Internet, but it does sound typical of issues you would have if you had a vacuum leak. I would triple-check all the hoses to make sure there are no cracks or leaks. - Wayne at Pelican Parts  
porvida Comments: 88' 325ix. Starts fine, idles fine. Starts to run rough and stumble at 2500 through 3500. At 3500 stops misfiring and runs great. Does it under load and in the drive way.

I have:
Adjusted the valves
Cleaned fuel injectors + new seals
replaced all hoses and double checked em all
New valve cover gasket
New Fuel Pressure regulator
New used o2 senor
plugs
Crank position sensor
exhaust seals and new exhaust

Running better of course but none of that made any difference in the stumbling.

Any thoughts are very much appreciated


Amazing of guys to offer this kind of help!
March 21, 2011
  Followup from the Pelican Staff: You've already replaced just about everything! I would revert back to old school here, and actually check the timing of the engine with a timing lamp. Sounds like it may have something to do with the mechanicals of the engine, rather than the injection or the ignition (since it runs fine everywhere else). Also run a compression check while you're at it, just to verify the condition of the underlying engine. But, I would suspect something is up with the timing at that rpm range. - Wayne at Pelican Parts  
bmw Comments: 1988 325i, convertable, tuned up ignition, cap etc. , took it to deq, did not pass, took it to a shop , note car was running great better than ever. Wife picked up car from adjustment. died 2 blocks away. something clicking when motor not running, relay? Got it started took it home. Checked all hoses, vacuum related. changed throttle switch sensor, idle valve, car starts ok , but surges now at idle . took to shop , code reader said idle control valve? installed new and old one, still surging, Mechanic pulled fuel line of of rail, no fuel pressure, changed fuel pump in tank, car starts now but still surges at idle.
March 12, 2011
  Followup from the Pelican Staff: Surging is almost always a mixture problem. Mixture problems are often caused by vacuum leaks. Although you've checked your car over again and again, I suggest that you use a smoke machine to check for vacuum leaks. I have an article on this here: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm - Wayne at Pelican Parts  
greenberg Comments: Hi Wayne,
I have a BMW 320iA 1989. The engine runs fine but is using too much fuel. The Mass Air Sensor cannot be adjusted to give normal readings for the CO and hydrocarbon levels. I have replaced the Mass Air Sensor, the Fuel Pressure Regulator, the Coolant Temperature Sensor and adjusted the tappets. I have cleaned the Throttle Body and examined for leaks in the various rubber boots on the air intake without finding any. The car is not fitted with an oxygen sensor
What else should I look at?
March 9, 2011
  Followup from the Pelican Staff: I would check the mixture pre-cat to see if it's running rich or lean - that will give you more clues on where to go next. - Wayne at Pelican Parts  
m42wrencher Comments: Hi, I read the article in hopes of finding an answer to my question nobody seems to have an answer to it. If I drive around with my ICV disconnected from the knob that flows into my engine, am I going to do damage to the engine? The rough idle is annoying, but my car is currently having issues... Do you possibly have an answer to this question?
February 21, 2011
  Followup from the Pelican Staff: Disconnecting the ICV is not recommended, but I don't think it will do permanent damage to your engine if I think I understand you correctly. - Wayne at Pelican Parts  
E30lover Comments: Hi Wayne.. I was failing the air care tests due to my car running lean. After reading the info that you provided I did a smoke test and found no vacuum leaks. To ensure no problems i did change a few of the hoses. I still failed the air care test. A tech at a bmw store here recommended that i use seafoam and see if that helps. I followed the instruction online and i re-tested the car and it passed however, my joy was shattered when the car had a difficult time starting up. The car starts for a few seconds and die. I have to press on the gas for 30sec and then it runs fine. I thought it was the seafoam so i drove the car for two weeks and found the problem to still persist. I changed the icv with a used one and no change. I also changed the MAFS and no difference. The techs at the local BMW store want me to do a second smoke test to see if the seafoam damaged any gaskets or hoses. I was thinking of replacing the ECM with a new one and also replacing Icv with a new one if the smoke test finds no leaks. The techs at the BMW were suggesting to do a complete rebuild of the engine to remove any carbon build-up. Please help
February 19, 2011
  Followup from the Pelican Staff: Sounds like a simple fuel injection problem, but it does sound like you replaced everything so far. I would perform a compression check and/or leakdown to see if you can find any issues. It indeed might be the ECU or the wire harness that attaches the sensors to the ECU - I would probably try a different ECU, and/or check the continuity of the wire harness with a multi-tester. - Wayne at Pelican Parts  
Alex Comments: Got a 1984 318i. It wont start unless I give it 1/2 throttle or more while turning over the engine in which case it starts up fairly quickly. It will die when I let off the gas and there is no idle whatsoever. Also, occasionally when keeping the throttle steady around 2500 the car will randomly bog down unless I give it more gas. I'm hoping for just a vacuum issue.

Thanks!
February 14, 2011
  Followup from the Pelican Staff: Yes, this could be a vacuum issue, or it could be a clogged idle control valve. I would inspect the valve and clean it, and also check all of your hoses / boots for vacuum leaks. - Wayne at Pelican Parts  
Rrrockhound Comments: My 87 325 will occasionally rev kind of high when first started, maybe to 2000 RPM or so. It settles down within a second or two but I'd rather not have it do this with cold oil. Does this count as an idle control problem?
February 12, 2011
  Followup from the Pelican Staff: It could be a vacuum leak - the extra air is acting like you are stepping on the accelerator. It may be the idle air valve, but I have found that these are pretty reliable when they are clean. You might want to take it out and make sure it's clean and free o the inside - that may fix the problem. - Wayne at Pelican Parts  
DaniTD Comments: Hi Wayne, my 318i M40 is winning me...
Changed the ICV and the TPS because of some vibrations on idle when warm especially, now it doesn´t have vibrations but the idle at cold is about 600-650rpm too low, when stopping and depressing the clutch the engine surges and when it warms it goes over 800-900-1000. It doesn´t surge but when you stop sometimes stands at 800, in other cases at 1000 and so. DME was checked and no faults were stored. What can I do next?
February 8, 2011
  Followup from the Pelican Staff: What you're describing can be caused by a bunch of things, but most of them would trigger a code in the DME. I will take a guess and go back to my old playbook which says that you probably have a vacuum leak in there. If you've checked everything already, you might want to pick up a smoke machine and smoke out the system to check for vacuum leaks. I've got an article on doing that here: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm Hope this helps. - Wayne at Pelican Parts  
MagD Comments: I have a 1987 325is 5spd. There are days that it runs great but every once in a while it will idle rough at around 800rpms and the throwout bearing sounds like a clunker. It will also stutter/slip or hesitate through all the gears and at all speeds. Since this problem is not consistent I don't know if the Idle Air Control Valve is malfunctioning when this happens or the clutch is slipping since the throwout bearing gets louder when the rough idle is going on. Any help please!
February 6, 2011
  Followup from the Pelican Staff: Sounds like you might have multiple issues that are compounding each other. The first thing I would do for the rough running is try to hunt down any cracked vacuum hoses that might cause leaks. Leaking hoses will confuse a lot of the components in the fuel injection system and result in improper metering of fuel.

Throw-out bearings typically don't clunk, but squeak and moan when pushed in. Also, they will typically not make any noise when the clutch pedal is out (pedal not pushed to the floor). When they begin to wear out, then when you push in the clutch, you will hear some noises there. Hope this helps... - Wayne at Pelican Parts
 
Jester Comments: just wondering what the black canister type thing is on my 1989 318i E30 with the M40B18 motor. It almost sits directly underneatn my powersteering resivoir on the passenger side left side it has 3 vacuum lines connected to it. I noticed while underneath the vehicle it doesn't seem to be sealed, I can see what seems to be black spongey type foam. should this be sealed completely? what is the purpose of the canister? would it cause irratic acceleration if it was completely sealed? by the way I had that comment from 2 december 2010. I recently pulled everything apart to do with vacuum lines, intake manifolds, too look for leaks still haven't solved the problem of erratic acceleration. recently pulled the injection system out n had it reconditioned n had the lower half of the intake manifold thoroughly cleaned, it was full of black soot.just about to put it back in. post updates later.
February 3, 2011
  Followup from the Pelican Staff: The device you're describing appears to be the fuel tank / evap charcoal canister. It's an emissions device that is used to scrub gas vapors before they are released into the air. Modern cars have done away with this component, working instead to have a sealed system. In general, this will not cause any performance issues, unless it somehow introduces a vacuum leak into the engine or manifold through a disconnected or broken hose. - Wayne at Pelican Parts  
landon81 Comments: I have a 1986 325e that has idled rough for over a year now. It got so bad that I had to put the car in neutral to prevent it from stalling when I was idling. After reading this article I purchased the air boot and all of the vacuum hoses. It cost me a little over $30 on pelicanparts. When i replaced the air boot there were a few cracks in it. Also, upon removing the breather hose there was so much build up inside the hose that I am not sure any air was getting through. After replacing all of the hoses I started it up an the car is running like a dream!!! Thanks for posting this article!
January 15, 2011
  Followup from the Pelican Staff: Cool, thanks for the feedback - vacuum leaks from cracked boots and hoses cause about 80-90% of the problems that I see from our readers! - Wayne at Pelican Parts  
ZEE Comments: Hey I am not sure what could be wrong with my BMW, it is a 1996 BMW 318ti, I was driving on the motorway then to an exit stop at the lights everything was perfectly fine and normal when the traffic lights turned green i pushed the accelerator and car just stopped, Attempted to start the car no luck waited a few minutes and tried starting again and it started but the idle was all over the place as soone as you press the accelerator it just dies.
January 12, 2011
  Followup from the Pelican Staff: Take a look at which fault codes the car is putting out. I have an article on this here: http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm - Wayne at Pelican Parts  
JimiRaveon Comments: Just an FYI. I have a 1986 325es. Once it got to operating temperature, the idle would continuously rise and fall between 800 and 1300 rpms. Found this forum and followed the instructions, which was very helpful, but it didn't mention one thing. I noticed that when I took the hoses to the Idle Control Valve off and tested it, it didn't look like it was operating properly but current was correct about 460mA, and was pretty dirty on the inside. Cleaned it out with Carb cleaner and problem went away. Just thought I would share that. Good luck to all.
January 10, 2011
  Followup from the Pelican Staff: Thanks for the tip and info. Great stuff. - Nick at Pelican Parts  
mr.t Comments: i have 94 325i i have problem on in climb to higher elevation going up when you step on gas the rpm and speed up and down 40mph to50mph and then40mph the speed will not go thrue normal what you think is the problem.
December 29, 2010
  Followup from the Pelican Staff: I don't have enough information to really figure out what the issue is, but the car does have an altitude compensator (barometer) that will work to adjust mixture for higher altitudes. I would guess that perhaps this is not functioning properly. - Wayne at Pelican Parts  
Si Comments: wayne,in my M40 E30, T shape idle regulator valve just has 2 pin electrical wire, and the valve has screw on side to mechanically open or close the butterfly valve inside.
how to check above part to know the function good or bad
thanks b4
December 20, 2010
  Followup from the Pelican Staff: There are a few different versions of this valve, and I'm not 100% sure which one you have, but here's what I do for checking the valve. Firstly, I make sure the car has no vacuum leaks, as this will cause the valve to become somewhat useless (air will get into the system past the valve). Then, I disconnect the valve and watch the internal valve to make sure it opens and closes as you rev the engine. I also make sure I clean it out with some isopropyl alcohol and some q-tips. If I'm thinking about the valve that I think you have in your car, I believe that the screw on the side of the valve is to manually adjust the idle up or down when you're tuning the car. - Wayne at Pelican Parts  
Mototornic_Junk_Line Comments: Wayne, Wayne. After thoroughly inspecting all vacuum and all wiring and finding that everything was good. I had one last option. Change out the Mototronic Dme 173. I have spares but this one i just bought actually. I ran the car with its crazy idle. Unplugged the DME while the car was operating and plugged in another. The car idle normally. I thought "no way!" i tested a third DME that works, but the car cuts on and off after it heats up. The car idled normally. I then went back to the original and plugged it back in. the car idle was crazy again. It was a bad DME that i just bought less than a month ago. sheeshh.....
December 17, 2010
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
POS_E30 Comments: the car idles normally with the air meter unplugged. As soon as i plug it in, the idle acts crazy. So i assumed the air meter might be giving a bad reading. It is only 4 months old and I have a lifetime warranty on it so i exchanged it for a brand new one today and the problem still persists. Without a smoke machine, I have completely searched the engine compartment for a vacuum leak, the only one present is the throttle body butterfly, other than that, the system is air tight. maybe i have a cylinder not firing. im gonna check that tomorrow.
December 16, 2010
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
325iSuck Comments: ok wayne, my idle is everywhere now. up down and all around. mostly high though. I preformed a test to see if i have a leak in the system. I removed the ICV and plugged the 2 holes, and cranked the car. The car started right up with no problems and idled perfect. I mean 750 rpms, no shutter, perfect. So this concludes, I am assuming, that i have a major major leak in the intake system, right? I was thinking maybe the butterfly on the throttle body is not sealing properly. so i removed the breather with the car is idling. the car dies when i use my hand to stop the airflow through the elbow. The car suffocates and dies instantly, plus it suctions my hand to it. Is the throttle body butterfly suppose to make an airtight seal or can the car idle fine without the ICV?
December 15, 2010
  Followup from the Pelican Staff: The butterfly will not be able to seal 100%, that's for sure. But, it should seal mostly. I do think that you might have a leak in the air flow meter butterfly valve then. The ICV stabilizes things - it's not simply just for idle. If your valve is not working properly, then it might be letting in too much air as well. I had a problem with that I thought was with this same valve on my 959 - I watched as it opened and closed and did a whole bunch of tests on the valve. Turned out that it was the mixture that was causing the poor idle. Maybe take a closer look at the mixture? - Wayne at Pelican Parts  
CrappyE30 Comments: Ok. Sorry i keep posting. I found out something very strange. The car idles at 1600 when the car is in motion. it drops to 1000 when sitting still. i did several tests and this is a fact, not a theory. there must be some kind of sensor on the differential affecting the icv in some way. but for what reason?
December 14, 2010
  Followup from the Pelican Staff: Nope. Probably just a huge vacuum leak or stuck air flow sensor that is picking up more airflow through the front grilles when the car is in motion. - Wayne at Pelican Parts  
M20is2fast Comments: my next idea is to replace all the injectors with 19lb injectors and purchase the silicon vacuum hose kit off ebay for $90 or so. Ill let you know how it goes.
December 14, 2010
  Followup from the Pelican Staff: Thanks for the follow up. Keep us posted. - Nick at Pelican Parts  
MyE30is2fast Comments: Thank you for your reply so quickly wayne. I recently did a complete upper engine overhaul and replaced all the gaskets and took the head to the machine shop. The problem I am having is the idle will float before it drops. If i step on the accelerator and immidiatly let off, the idle will float at 1700 rpms, then slowly drop down to 800. Once its idling, its good and smooth. there is a 13 pin connector under the intake that looked a little curroded so i chopped it out and fused all the wires together with barrels. I forgot to mention also, i replaced the computer, twice. so now i have two known good 173 ecu's here. I also recently installed a new o2 sensor and I think my cat was clogged so i cut it out and ran straight pipes. muffler still exists though. I recently replaced fuel pump and swapped out pressure regulator with known good one. I thoroughly cleaned the inside of the throttle body and the elbow boot is fairly new. I also recently replaced a couple ignition wires and the coil and the cap and rotor. I know the idle acts funny if there is air in the coolant but it has been bled to the max.
December 14, 2010
  Followup from the Pelican Staff: After spending a lot of time trying to troubleshoot my Boxster 3.4 conversion, I learned first-hand that you should check completely for vacuum leaks prior to replacing any parts or messing around with anything you might think may be causing a problem. I recommend a smoke machine, you can see my article with the URL listed below. I know I'm beginning to sound like a broken record, but I've found that about 75% of the time with these idle issues, it can be traced back to air entering the system when it shouldn't. - Wayne at Pelican Parts  
DavidsFast_e30 Comments: My idle was erratic. Mostly idling around 1800, even while driving the ICV was wide open which caused the car to jerk when i let off the accelerator. I went gung ho! I replaced TPS with new one. installed a brand new MAF. replaced the vacuum hose under the throttle body. Installed new Temp sensor. thoroughly cleaned ICV and throttle body. Idle is still stupid. I just dont get this car!
December 13, 2010
  Followup from the Pelican Staff: It could be something like the manifold gaskets creating a huge vacuum leak. I recently wrote an article on checking for vacuum leaks, take a look here: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm - Wayne at Pelican Parts  
karlos Comments: Hi my 89 325i starts to idle very low after you drive it for a bit it, starts fine and idles around 700/800 rpm then when it gets warm it starts idling erratic about 400-600 and when driving if i come to a set of lights and if i dip down the clutch to shift downgear the revs drop to low and the Engine just cuts out and dies like as if the idle valve dosnt kick in in time to stop it it happens now about a third the time i have to stop at lights or in traffic
any ideas?
cheers Karl
December 13, 2010
  Followup from the Pelican Staff: It could be a number of things, but I would start looking for vacuum leaks first. When there is a vacuum leak in the system, more air is drawn in past the sensor, and it can't meter the airflow properly. Due to the vast amount of air coming into the fuel injection system at higher rpm, these types of vacuum leaks only seem to really appear at lower rpm. - Wayne at Pelican Parts  
Si Comments: Bro,
my E30M40 having problem with Engine Idle ,once Air con Switched on only when car in running condition in any gear and I kick down clutch pedal to shift down the gear the engine speed drop and die, the problem not happen in every time...please advice bro what happen in the system...
thanks in advance
December 12, 2010
  Followup from the Pelican Staff: The car has a system in place to kick the throttle open a little bit when the A/C turns on - sounds like the switch or mechanism is not working properly. On your car, however, I'm not sure how this system is controlled. - Wayne at Pelican Parts  
Jester Comments: hi i have a 1989 E30 318i, gone over all the hoses even replaced ones that were flimsey and hardened, replaced the middle section intake manifold gasket and the throttle body gasket replaced both with paper and peramtex black silicon to make sure theres a good seal. still having erratic idle. repositioned the throttle position sensor and checked over the control valve they seem sweet, it idles fine only when the mass air flow meter is disconnected circular 5 pin plug if that helps. box type flow meterif i reconnect the meter it idles all over the place not exceeding 1500rmp but will idle so low that it will bring things to a stand still and the engine shuts off. do u reckon it could be the meter or could it still be the TPS, tested it with a multimeter for continuity at its full closed position and Wide open position which was ok, tested it for ohms i would get a reading but they weren't consistant readings? does the same thing with my brand new TPS also, what do reckon. sorry bout the long message
December 2, 2010
  Followup from the Pelican Staff: I'm still guessing vacuum leaks. I would use a smoker machine to triple check. Check out the article I wrote on this here: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm - Wayne at Pelican Parts  
FdSwift Comments: I have an'89 325is w/idle prob.Check engine light came on.Went through all the usual stuff.Finally called my BMW car club tech repin N.Cal;He asked if I could hear a hissing noise nearish to the firewall.Said yes,he suggested that it could be the intake manifold gaskets of either/both cylinders 5&6.Nasty job removing manifold but sure enough both were tornthey are just paper.Replaced them and now car idles much smoother.Hope this helps.
December 1, 2010
  Followup from the Pelican Staff: Cool deal, thanks for sharing. Vacuum leaks are a huge contributor to this problem! - Wayne at Pelican Parts  
aleco Comments: Bought an 87 325i AUTO. Car idles terribly between 1 and 2. Even does it while driving up to approx. 40mph. I've looked over all the hoses and it has a new idle valve. 2 friends said there is an idle ecu somewhere near the glovebox. Do you pull the glovebox out to get to this? Should I bench test it somehow when I find it?
November 22, 2010
  Followup from the Pelican Staff: Poor idle is usually caused by vacuum leaks that are letting air get past the throttle body, especially on these older cars. I would take a closer look at all of the rubber vacuum hoses first. - Wayne at Pelican Parts  
bemmer Comments: The idle control valve controls the amount of air that bypasses the throttle butterfly and keeps the engine idling. The throttle switch is used to control the idle control valve. Essentially, when the throttle is fully closed, the throttle switch sends a voltage to the idle control valve. This voltage opens the valve and allows air to pass, increasing idle speed. Now, connect the multimeter between the two outer terminals on the valve and check for resistance. There should be around 40 Ohms of resistance. Now check the center terminal and each of the two outer terminals. There should be roughly 20 Ohms of resistance between them. If you do not get these values, the switch has gone bad and must be replaced. two outer terminals on the valve and check for resistance are you talking about the connector that connects to the ICV as the outer terminal
November 16, 2010
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
branekol Comments: hi thanks a lot for sugestion.
October 11, 2010
  Followup from the Pelican Staff: No problem. - Nick at Pelican Parts  
Si Comments: Hi there, need your info here for the Throttle switch pin,
18 and 2 is for Idle valve actuator,please advice what is the 18 and 3 used for.thanks
October 4, 2010
  Followup from the Pelican Staff: Here's some great info from bemmer:

The idle control valve controls the amount of air that bypasses the throttle butterfly and keeps the engine idling. The throttle switch is used to control the idle control valve. Essentially, when the throttle is fully closed, the throttle switch sends a voltage to the idle control valve. This voltage opens the valve and allows air to pass, increasing idle speed. Now, connect the multimeter between the two outer terminals on the valve and check for resistance. There should be around 40 Ohms of resistance. Now check the center terminal and each of the two outer terminals. There should be roughly 20 Ohms of resistance between them. If you do not get these values, the switch has gone bad and must be replaced. two outer terminals on the valve and check for resistance are you talking about the connector that connects to the ICV as the outer terminal - Nick at Pelican Parts
 
branekol Comments: Hi. i hawe e30 320i 86g. and i hawe problem with idle. it is always on 1500 rpm. hawe any sugestions
September 29, 2010
  Followup from the Pelican Staff: Yes, check for vacuum leaks, as excess air bypassing the throttle body will cause a high idle. - Wayne at Pelican Parts  
London Comments: I have an 1986 325es and sometimes when I start my car up it revs to about 2000 and then drops back down to an idle that wiggles between 700 and 1000 rather unsteadily. And more often, the engine starts and the initial rev doesnt reach over 1000, or even 800, these times the car doesnt run as well and the idle speed fluctuates lower. Thoughts? Going to replace the IDC tomorrow
September 28, 2010
  Followup from the Pelican Staff: Sounds like the vehicle either has a large vacuum leak or it is hunting for an idle. Either way you'll want to check the idle motor, if it barely open, there is a vacuum leak. If it it appears to be somewhere in the middle, it may be ok until the problem occurs. if you disconnect the idle valve, does the engine idel normally? - Nick at Pelican Parts  
Traikun325e Comments: Nice article, I plan on going through the bimmer and getting through some obviously busted vacuum. My question: Can blown vacuum lines alone cause a idle RPM of 2000 or so?

1985 BMW 325e

The idle doesn't surge, it just idles at 2000 or so RPM. I tested the AFM's resistance as per the hayne's manual, pins 7 & 9 on the ECU connector after cleaning it, starts at about .600 resistance on 20k setting with the vane closed, peaks at about 1.000, then drops to about .300 as I open it completely. Doesn't seem to have a flat spot, but I'm certain while resistance was rising it seemed to drop once or twice as well before it reached 1.000 and started dropping, I mean. Is this normal operating conditions, or is it shot?

thank you!
September 7, 2010
  Followup from the Pelican Staff: The air flow meter should be uniform, not jumpy like you described. I'm not sure about the specific behavior of that air flow meter, but if you indeed have vacuum lines that have leaks, they will suck air into the engine and bypass the meter. - Wayne at Pelican Parts  
Free Bird Comments: hello i have a 1986 BMW 325e, i replaced one of my coolant hoses a few days ago and did not secure it tightly and it poped off on the highway. : my car over heated and engine died. after cooling down it has trouble starting and when it dose start have to give it lots of gas so it wont die on me, and is still overheating when i get on the highway?
August 23, 2010
  Followup from the Pelican Staff: Fill the car up with coolant, and make sure that you have fully bled the system. It sounds like something may have been damaged (vacuum leak) by the overheating, hopefully something simple. This is nearly impossible to determine over the Internet. - Wayne at Pelican Parts  
Ty Comments: I have a 94 325i with a surging idle problem. I have removed the IAC valve, and with the key on, it buzzez, but does not move. Is this an indication that it has failed?
thanks
August 23, 2010
  Followup from the Pelican Staff: I think that's normal for that valve. Surging is a mixture problem, which is often caused by a vacuum leak. Triple-check all your hoses and boots to make sure they are tight and leak free. - Wayne at Pelican Parts  
Si Comments: Hi ans,

have you clean the Air Flow Meter, specially on the swinging window and the inside housing..just spray it with carburetor cleaner, let it dry and put it back...and see what happen, you may need to adjust the spring gear position if the idle still not good..
August 20, 2010
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
nescid Comments: The threads of posts and advices here are very accurate regarding erratic or surging idle issues. I sell OEM used BMW parts especially the E30's. I have owned about 8 of them in the family. I have a very good Engine with the Transmission. It came from my daughter's first car. It was hit on the rear and spunned on the freeway. The Lord is so good, my wife hit her head on the side window, and went to a therapy, daughter was safe. The car missed slamming into the freeway high wall by just an onion skin. Thanks for this well built German engineering also, it paid off in a way as opposed if I have gotten a lighter gauge built shell car. Engine was still running very fine after accident. There were no issues whatsoever and a very strong running car. I am located in Southern CA. Car has 128Kmile. Been sitting in my garage for 7 years now. I do carry a lot of used E30 parts. I have over 5000 feedbacks on ebay. My e-mail is nescid1@verizon.net
August 11, 2010
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it. Glad everyone was OK.
- Nick at Pelican Parts
 
Drew588 Comments: Gay, I have an 86 325e, and when i turn it on it reaches almost 3000rpm then drops to 500rpm then back to 2000rpm and just keeps dropping and reving continuously. i have replaced the air flow meter and didnt do anything. do you have any suggestions?
August 11, 2010
  Followup from the Pelican Staff: This is called hunting, and is almost always caused by the mixture being either too rich or too lean. Have the mixture checked pre-CAT in the exhaust, and then adjusted - it should go away. Vacuum leaks and a sticky idle control valve will also sometimes cause this as well. - Wayne at Pelican Parts  
Bill Comments: Still can't find the erratic idle on my 325i. Have replaced the Mass airflow sensor,the throttle body, idle valve, and ECU from a good running car as well as changing the vacuum hoses and a new bellows from pelican. It still has a surging idle that goes away when in gear but the RPM is quite a bit higher. like a vacuum leak I am ready to junk this thing.
August 8, 2010
  Followup from the Pelican Staff: Take a look at this article I recently wrote on troubleshooting vacuum leaks. It's written for the Boxster, but it's very applicable to the BMWs. http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm - Wayne at Pelican Parts  
Graz Comments: I have an E30 320i, when the engine is cold it idles fine, but when warm the idle seems too low and it stall every time I come to a stop. Any suggestionsd greatfully recieved.
July 27, 2010
  Followup from the Pelican Staff: Check for vacuum leaks. As the car heats up, the rubber expands, and it may be creating some leaks that don't exist when everything is cold and semi-sealed up. - Wayne at Pelican Parts  
lovelove Comments: i just had my egnition switch changed in my 1994 325i and 1 minute after I left the mechanic my car was idling realy high to the point that my car started smoking after 5 minutes, my mechanic claims he doesn't know the problem and this is not his fault, my car has been there for 21/2 wks and i had just picked it up from having fuel pum replaced 2 1/2 wks ago and a day later my egnition switch went now when i pic up i have this problem any suggestions
July 27, 2010
  Followup from the Pelican Staff: The good news is that the car will try to tell you what is wrong with itself. Check out my article on BMW code reading: http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm - Wayne at Pelican Parts  
Bruno Comments: My 1996 328i passed smog inspection EXCEPT for an item called "EGR Visual". The shop noted that the Idle Air Control Hose needed to be replaced, and they quoted me an exorbitant price for the job. Can you tell me what Pelican part this is and where this hose is located so that I can do the replacement myself?
July 18, 2010
  Followup from the Pelican Staff: I don't have a good photo of that engine compartment, but the idle air control valve is what feeds air to the engine when the throttle body is closed. It's located right near the throttle body and should have two or three hoses attached to it. If you give our sales dept a call at 1-888-280-7799 a ring, then can get you the proper hose. - Wayne at Pelican Parts  
Rob Comments: hi i have just purchaced an 89 e30 it idles fine but once warm during normal driving under acceleration slight or severe power surges on and then slightly less aprox 1.5 secconds each way i am unsure but think maybe the auto choke is malfunctioning at regular operating temp as it runs smooth as whn cold any help much appreciated.
July 6, 2010
  Followup from the Pelican Staff: This could be a bad mass air flow sensor or a fuel delivery problem. - Nick at Pelican Parts  
ans Comments: Hi, I have a serious problem with my 318i '89 model. The car starts fine and idle seems okay but after a few minutes, I hear a slight dip in the idle. When I then try to accelerate, the rev increases to +-2500rpm and drops again to +-800rpm swinging the whole time while my foot remains on the accelerator. The revs do not go past 2500rpm. I changed the fuel pump and checked for vacuum leaks but still have'nt found the problem????? Please help.
July 1, 2010
  Followup from the Pelican Staff: It's nearly impossible to diagnose problems like these, but perhaps there's a problem with the idle air control valve? When the car is heating up, this valve is open a bit and then closes up when the car gets warm. - Wayne at Pelican Parts  
Si Comments: Bro, Thanks for Advice. The problem was solved,there one problem on The ICV's, after take out and check I just Spray the Connector pin with Electrical cleaner since the continuity of internal wiring okay and spray the inside valve with Penetrating and Cleaning Oil, let it dry and Put it back..this is for Share
June 20, 2010
  Followup from the Pelican Staff: Thanks for the follow up. We appreciate it.
- Nick at Pelican Parts
 
gar Comments: hello, 1992 BMW E30 325ic.
The idle never move up and down one day. It worked perfect yesterday, but today no idle and no speed shown. The car still runs great except the above two just happened. THnanks!!
June 19, 2010
  Followup from the Pelican Staff: Are we talking about the engine idle or the tachometer? - Nick at Pelican Parts  
Si Comments: Hi there, I have problem on Idle engine speed once the A/C swithced on..it just 450 rpm..without A/C switched on the idle speed can reach 850rpm...as per my experiance it should be consistance on betwen 700~900rpm even the A/C has switched on...any one have an Idea..what went wrong here..Thanks
June 14, 2010
  Followup from the Pelican Staff: When you switch on the A/C on these cars, the engine is supposed to get a little more throttle / air in order to counter act the additional load from the A/C. Unfortunately, I'm not very familiar with how the system works to achieve this (I believe a signal is sent to the computer, which then opens the aux air valve a bit more at idle). - Wayne at Pelican Parts  
Larry F. Comments: Wayne:
The smoke machine would be great; and I love the Tip: "borrow it from a friend"! I have had several opinions to the effect that my last vacuum leak you can tell from my correspondence that I have cured a handful already is likely a work rear crank seal. Factory clutch in this '88 325iX is still working fine, so I think I will just tolerate the slightly high idle when warm.
Thanks, Larry F.
June 12, 2010
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
jerry Comments: I have 528 1999 when the car is cold rpm go down every 10 second, once car warms up all is normal, any ideas??
In the past got oxygen sensor bad on my readout, the one before catalityc converter but has got normal now. tool
June 11, 2010
  Followup from the Pelican Staff: I would check for vacuum leaks, and also check the idle aux air valve - I believe that your 1999 should have one (I have the same car). - Wayne at Pelican Parts  
Stewy Comments: Hey, I recently bought a 1984 E30 Automatic. It drove well for the first couple of months, but now has some serious idle issues. It idles anywhere between 600 and 3000 rpm. It only has a problem when I lift my foot, as long as I give it some it is fine but its very painful at lights and in traffic. Is there any chance I can get a more detailed description on your ideas to fix the problem as i am still only learning the ropes of this car? Thank You
June 11, 2010
  Followup from the Pelican Staff: Same thing as above - check the idle air aux valve - these get dirty. Also, big vacuum leaks will cause this problem - check all your hoses for cracks and breakages. - Wayne at Pelican Parts  
lui Comments: I have a 328 is 1998 when run cold the motor run bad and i push gas pedal and problem disapear why
June 10, 2010
  Followup from the Pelican Staff: Is the check engine light on, have you checked the fuel pressure and looked for a vacuum leak?
- Nick at Pelican Parts
 
Larry F. Comments: Wayne and Other Smart Staff:

I need help on an idle problem:

The Car:
- '88 325iX, 244K 2-door, 5-speed, very sweet

The Problem:
- Idles dead cold pretty well, ~700 rpm
- Idle slowly climbs as it warms up, sometimes stopping at 1,000 rpm, sometimes up to 1,500 rpm
- Sometimes snaps back to normal idle when fully warm, but does not stay there.

Work So Far:
- Totally current on maintenance: fuel filter, air filter, plugs, plug wires, dist cap and rotor, valves adjusted
- Vacuum leak work: new AFM boot, new breather hoses, new vacuum hose to fuel press reg, valve cover gasket and cam plugs
- Parts replaced: throttle position switch was bad, thought this was going to be "It"!, idle motor, which also "buzzes" OK, tests 20-0-20 ohms, moves freely, ECU for other reasons, had to replace the computer, coolant temp sensor, O2 sensor, other unrelated items
- Other tests: suspecting possible wiring problems; temp sensor resistance readings good at the ECU connector, voltages found at the idle motor ar 6v - 12v - 6v.

Signed, Stumpted in Seattle

June 3, 2010
  Followup from the Pelican Staff: High, rising idle is very often a vacuum leak that opens up further as the car gets warm. I have a new, better article on finding leaks here: http://www.pelicanparts.com/techarticles/Boxster_Tech/21-FUEL-Vacuum_Leaks/21-FUEL-Vacuum_Leaks.htm . The smoke machine is really the key when trying to troubleshoot something like this. - Wayne at Pelican Parts  
Joe Comments: 1989 BMW 325i - Barely idles at warmup 1-2 minutes and then slowly comes around to a somewhat normal idle.
After it's warm, I snap the throttle - it lands below normal idle momentarily and then rises to normal idle.
Checked/Replaced ALL relays and sensors.
O2 sensor new - preheater relay new & operational BUT NO VOLTAGE 12V at O2 CONNECTOR pos#4 neg#3. There is continuity the wire from relay to O2 sens connector & There is continuity from relay to Motronic plug #23. Niether wire is shorted.
Motronic bad & not sendind signal to relay?
ICU,air flow meter, TPS, purge valve, both temp sensor & switch @ thermostat new and/or operating.
Just found this website - has lots of information!
Thanks for any input.
May 23, 2010
  Followup from the Pelican Staff: I would go back to basics to start and check for vacuum leaks everywhere. These cars are notorious for running like this with even a tiny leak in the intake vacuum. - Wayne at Pelican Parts  
zep06 Comments: This article is great! I fixed my idle problem after a year of toying with it. The cars idle would surge from 600 to 1000 rpm but never die, and it wasnt 100% consistant, but it turns out, the throttle switch had become miss calibrated. I went ahead and replaced it because i couldnt get continuity with the throttle nearly closed. Thanks pelican
May 19, 2010
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
Q Comments: Hi, I have the same problem as deany - posted 2nd April 2010:
I have a 1991 e30 318i with 114k. my problem is whenever i drive slowly the car is very jumpy. if i put it in first gear slowly releasing the clutch and without any throttle it jumps like mad. driving in urban areas in the lower gears also causes this erattic jumping, as though i'm constantly applying and then immediatley lifting off the accelerator.this is leaving city driving very difficult.

Is there any feedback on this? Many thanks!
May 12, 2010
  Followup from the Pelican Staff: Hmm, that's very difficult to diagnose over the Internet. Sounds like it's really down on power and that is what is causing the problems. I would start with the basics, look for vacuum leaks that would cause low power loss? - Wayne at Pelican Parts  
Bunny Comments: What does the hose coming off the throttle body and runs to the back of the engine go to? My 325e 1984 appears to have a leak in this hose. I have loud hissing noise, rough idle, and carb cleaner sprayed behind the engine where I assume this hose ends smooths/increases the idle speed. I have new hose, just wondering how much "fun" it's going to be to get at the back end of this hose and if it makes sense that this is the problem with the rough idle. Thanks!
April 29, 2010
  Followup from the Pelican Staff: I'm not sure 100%, as this varied with different models around the world, but the hose probably connects to your idle control valve which is responsible for controlling bypass air around the closed throttle body (at idle). Sounds like you have a clear path of what needs to be done! - Wayne at Pelican Parts  
Bimmer 318is Comments: PROBLEM SOLVED. Hi guys member my problem with the rough idle and the revs getting stuck at 3000 rpm. Problem solved. i went to the wreckers and i bought a second hand ICV idle control valve. my idle issues went away, this was after making 100 percent sure there were no vacuum leaks. i would suggest buying a brand new ICV if possible because you have to be lucky to get a good second hand one like i was. cheers
April 25, 2010
  Followup from the Pelican Staff: For clarification for everyone else - the ICV is an idle control valve, and it's responsible for controlling the idle air passing by the throttle body on the fuel injection system. These can become dirty and clogged, and then get stuck open. You can try cleaning it, but it's tough to clean way down inside - best to buy a new one. - Wayne at Pelican Parts  
JimS Comments: I have a 92 325 i convertible. Erratic idle when warm. I think I have a vaccum problem. Where can I find a diagram of all hoses. I think one may be missing on a can like device on drivers side under the intake boot. Also there is a vacumm valve with no connector, just a wire and a hose from the other end located on drivers side close to fuel injector electrical connector.
April 3, 2010
  Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799. They can help you get the manual you need.
- Nick at Pelican Parts
 
deany Comments: hi
I have a 1991 e30 318i with 114k. my problem is whenever i drive slowly the car is very jumpy. if i put it in first gear slowly releasing the clutch and without any throttle it jumps like mad. driving in urban areas in the lower gears also causes this erattic jumping, as though i'm constantly applying and then immediatley lifting off the accelerator.this is leaving city driving very difficult.

many thanks
deany
April 2, 2010
  Followup from the Pelican Staff: Is the idle too high or too low, have you checked the throttle switch for correct adjustment?
- Nick at Pelican Parts
 
mike Comments: hi there i have an 84 318i and i cant seem to figure out where the vacum hose from the throttle butterfly goes and the engine seems to be misfiring could that be the reason why and where does this hose connect to? i would appreciate any help if possible thanks alot.
March 15, 2010
  Followup from the Pelican Staff: it looks like there is one vacuum line that goes to the vacuum advance solenoid. If the hose is leaking it could cause a misfire.
- Nick at Pelican Parts
 
pete Comments: 325i e30 idle prob motronic 1.3 1991.checked temp senders tps continuity good in wot and closed. car will not idle unless i put hole in oil cap or twist the icv open loosened the lug to do this. have tried three icv all the same. take of tps connector idle goes up to 2000 i think this is normal.checked voltage at icv plug centre to ground 12v oute to inner 10v and 4v on the othe side.these should be both 10v ithink. turn ignition on icv snaps shut this is what is starving engine of air.my next step will be continity from 33/34 pin on ecu connector to icv plug to see if wire faults. have tried another ecu both 173,s going to try the latest motronic 380 next.the engine is totaly rebuilt and brand new bmw head so running like a sowing machine but should i need a hole in my oil filer i have a stocking over it to stop crap getting in. please can you help its driving me nuts. loom was installed good all connections good i am at a loss with this one. have tried stomp test it wont flash atall any codes nothing has bm got a code reader for the diagnotic plug bulkhead next to fuse box ?????ps car was origanaly a 320 i but it didnt idle good then since convertion tried two new eci cos it had the 172 in. cheers
March 13, 2010
  Followup from the Pelican Staff: You should have 12v on pine 2, the other two pins are grounds from the dme. Both will be on at the same time. this is how the dme controls the idle valve. I would be looking to make sure those signals are there and switching, if not it could be the dme.
- Nick at Pelican Parts
 
jonnywalker.sandiego Comments: I have an idle problems as well. I have a 1993 318is. Just replaced the icv and the two hoses that connect to it. I drive the car and at a stop, the idle works very erratic, bouncing between 500 and 700 about. I am going crazy over this issue. No engine light is triggered.

The other one is with the transmission, the cog lights comes when the a sudden change of speed and I hear like a jerk sound coming from the rear axle and then the light comes on. PLEASE HELP ME, to fix this problem. John Walker
March 5, 2010
  Followup from the Pelican Staff: I would start by checking for vacuum leaks and also scanning the complete vehicle with a factory scan tool to check for faults.
- Nick at Pelican Parts
 
Bimmer 318is Comments: Hi, i have a 1990 e30 318is and after driving for about 10 minutes my revs will randomly jump to 3000 to 3500 and remain there for about 2 minutes. and then calm down to normal, and whilst i am driving i have no power whilst this rev spike takes place. however this does not happen every time i drive. i am thinking i need to replace idle air control valve, or clean it some how if possible. thank you.
February 27, 2010
  Followup from the Pelican Staff: Check to see if the idle valve is sticking, if it is I would replace it.
- Nick at Pelican Parts
 
Dan Comments: Dear Pelican Staff,

I have been having an odd idle problem. Usually my 1987 325IS will idle and drive fine, and other times it will idle very erratically. The RPM's will drop very slowly, creating an odd and annoying driving experience where I can't downshift or change gears smoothly. I have encountered a lot of idle problems, but this one is odd. It seems like a valve or something isn't opening and closing correctly.

Symptoms while the car is acting up:

-When going from one gear to the next, the RPM's will drop very slowly, not nearly fast enough to meet up with the next gear.
-When pushing the clutch in from about 3000 RPM's, the RPM's will drop slowly to a random number, usually about ~2000 RPM's, but sometimes anywhere from 1000-3000.
-If I play with the gas while it's idling high at a stop, sometimes the RPM's will drop to a perfect idle very dramatically, as if a valve or sensor caught itself and started working properly.
-If I put it in gear while at a stop with my foot on the brake and try to force the RPM's down with the clutch, the car will choke a bit and jump back up to the high idle most of the time, other times it will fix the idling.

So far I have changed my AFM and tried 4 other ICV's.. My response improved with the AFM, but the idle problem still rears its head randomly. Different ICV's definitely seemed to change how often or how dramatic the problem was though.. I am going to try to find a new throttle switch next.. Hopefully that works. Otherwise I would appreciate any help you guys could provide. Thank you,

-Dan
February 18, 2010
  Followup from the Pelican Staff: I would check the throttle switch to make sure it is adjusted correctly.
- Nick at Pelican Parts
 
big rey Comments: hi iv got an e30 318i 1988 and im having trouble with my idle sometimes it fine then other times it revs to nearenough 3000rpm but it seems it only starts playing up when your driving along then when you stop it keeps revingh i just cant figure it out
February 17, 2010
  Followup from the Pelican Staff: I would check to see if the ICV is sticking, also check for vacuum leaks and see if the idle switch is adjusted correctly.
- Nick at Pelican Parts
 
Gradicus Comments: I just rebuilt my 97 318i engine. E36 M44 I believe. The idle doesn't bounce or anything, it's just consistently to slow at 500 rpm. It doesn't seem like a leak. Could it be the throttle cables? Thanks.
January 28, 2010
  Followup from the Pelican Staff: Yes, you may have the throttle plate misadjusted. - Nick at Pelican Parts  
nick Comments: any idea what could couse the idle to jump from 400rpm to 3000rpm i tested the icv and that wasnt the issue the tps was loose but could that really be the couse of nearly a 3000 rpm jump i baught new intake gaskets and hoses so to take care of any leaks great prices buy the way. so i was just wondering before i go throught pulling the intake manifold is it possilbly the tps
January 22, 2010
  Followup from the Pelican Staff: Does the idle still jump when the idle motor is disconnected? If so, check the mass air flow sensor and check fuel pressure and volume. A change in fuel pressure could cause an idle issue. That is assuming there are no vacuum leaks. - Nick at Pelican Parts  
rod Comments: I have an 88 325is, And I am experencing problems with my idle when I start my car it idles very eratic such as bounces between the 0-1 on the rpm meter, and sometimes when i stop at lights or stops signs my car doesnt idle steadily, but later corrects itself as I drive. I have replaced my timing belt and got fairly new spark plugs and got my valves adjusted but i cant figure out the problem.I noticed my gauges on the right side of my dash the rpm meter, temperature meter and mpgswent off and dont function, I got a new thermostat housing so,I dont know if that has anything to do with it. I have been having this problem and its very frustrating. I would like your help. Thank you
December 29, 2009
  Followup from the Pelican Staff: If the timing belt was installed correctly, that should not be an issue. Same goes for the other cooling system parts. If you idle is surging you should look for a vacuum leak in the intake manifold. Also check if you have a throttle switch or a throttle position sensor. You may have a bad idle speed motor as will but check for vacuum leaks first. - Nick at Pelican Parts  
jav Comments: i have an bmw e30 320i se, 113,000k on it, j reg 1991, run very nice with enough power, only problem i am getting is that it idles at 1500rpm and it stays there hot or cold, i changed the ICV, not change, no vaccum leaks i think, can you help me please, thank you
December 17, 2009
  Followup from the Pelican Staff: Difficult to diagnose over the Internet. Try inducing a vacuum leak and see if that changes the idle. If not, then there is probably one somewhere. - Wayne at Pelican Parts  
pfafftime Comments: I have a 1998 325is automatic that loses power after second gear. Runs good otherwise. Does not feel like the trans is slipping. No fault codes.
December 12, 2009
  Followup from the Pelican Staff: Not enough information to help much - check for vacuum leaks and also see if it runs perfectly in first gear if you put it in '1' and leave it there. If so, then the problem might be with the transmission. - Wayne at Pelican Parts  
nigel d Comments: i have 1995 316. idles fine when cold but as it leaves the "blue" section of the temp gauge the engine strts "missing" and dle drops to 200rpm and comes back. once the engine is warm all seems ok.
Most puzzling
any sugestions. I am in the uk so it could be just he weather
December 11, 2009
  Followup from the Pelican Staff: Check the codes, it shouldn't be doing that normally. If it's misfiring, it will almost certainly be popping out a code. - Wayne at Pelican Parts  
59mdb Comments: Have an 86 E30 325E with 150K on it. Have been trying to diagnose a coupel of recent issues with it I think related. If I pull battery Done 2wice - Idle runs fine at 750RPM then works its way up to about 1200RPM.. Replaced all vacuum lines And boot last year. Checked everythign electrical Have 2 wire IDle control valve12 V closes but can't physically adjust Using Screw to 400Amps runs at 550amps. Wondering in Idle computer bad Checked leads. If so where can I purchase.

Other issue is runnign up a long uphill after car has warmed About 10 minutes it starts surging Fuel gage swings from 15-20MPG's in a 1-2 second cycleDoes this till top of hil an for abotu 1 minute after then seems oK again for a while. Then it comes back.. It doesn't look like I can get codes for this old of a car can I Would like a code reader?? I have checked Water sensor, sender, and Throttle Switch Resistance, MAP & Cold start valve By running unplugged, Changed all the plugs, wires, Distributor Cap and ignition coil Had a high primary resistance. Also have changed the fuel filter and ran Injector cleaner through it as well have tried plugging off the Charcoal canister intake looked wet at vapor vacuum entrance into throttle body.

Also for reference both fuel pumps were changed 3yrs and 10K mile ago. Issue started beginning of summer abotu 2k ago and getting progressively worse.. Finally checked most all the inputs at the Idle fuel computer and Motronic computer plugs..

Since it swings Guessing it is a sensor or computer cutting in and out when it gets hot.. but not sure how to figure out which one Guessing Idle control valve or Water sensor.

Any Advice on getting a code reader Not getting check engine light so not sure if that will find my issue or reccomendations on computer replacements.. This car has the Conforti Chip in it as well. I love the car, but I don't want to find the issue by failure and being stranded..
December 2, 2009
  Followup from the Pelican Staff: I would start with the basics, pull the chip and any other mods you may have done and bring it back to stock, and see if the problems still exist? - Wayne at Pelican Parts  
mike Comments: Hi pelican staff i have a 87 325 im having trouble with my car it idles crazy. it will get up to 1100 rpms and go down and up when its warmed up. And when i give it gas and let go the rpm go crazy to.
November 26, 2009
  Followup from the Pelican Staff: If you idle is surging you should look for a vacuum leak in the intake manifold. Also check if you have a throttle switch or a throttle position sensor. You may have a bad idle speed motor as will but check for vacuum leaks first. - Nick at Pelican Parts  
Jeffrrw Comments: hi i have an 90 325i, i recently replaced the belts, spark plugs, did the valve adjustments, water pump, thermostat replacement. Also i replaced the intake boot and several vacuum hoses but i still experience a rough warm idle, but it idles fine when cold, any suggestions?
October 1, 2009
  Followup from the Pelican Staff: You might want to use a "smoke machine" to check the intake for leaks that you can't detect with your eye. Most good shops have one, if you can borrow it. - Wayne at Pelican Parts  
joonsup Comments: Hi I have 1990 325i and did a head swap this past weekend. When firing it up it idled poorly with the shakes and threw a afm code at first. After resetting battery, it now throws a 1222 lamda code although it idles better than before. Idle is smooth when a/c is on. Suggestions? Thanks
September 29, 2009
  Followup from the Pelican Staff: Sounds like an O2 sensor problem? I would check out this article here: http://www.pelicanparts.com/bmw/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm - Wayne at Pelican Parts  
chiselwizard Comments: Hi, I have a 1996 e36. The idle has been lumpy for some time when the engine is cold but got better, still not perfect, when the car warmed up. Now it starts ok but won't idle at all. Does this sound like a vacuum problem? Thanks
September 20, 2009
  Followup from the Pelican Staff: Bingo! Sounds like a vacuum problem. Check all of your hoses, or use a "smoke machine" if you can borrow one to try to find the leaks in your car. - Wayne at Pelican Parts  
deaconkane Comments: Sounds like mine but it will idle at 5000 rpms at times and go down to 2000 rpms. I also have the control under the dash, how do I check that? thanks..
September 18, 2009
  Followup from the Pelican Staff: It's difficult to give advice without being there, but I would also make sure that you check the whole intake for vacuum leaks. - Wayne at Pelican Parts  
KABUSAF Comments: I have a 1991 BMW 325i convertible. The a/c quit working all of a sudden. I have checked the fuses,they are ok. I found that there is no power to the low pressure switch. The a/c switch when pressed lights up and the idle speed goes up as it is supposed to. I checked the wiring diagram in my Haynes manual and I believe the problem is a faulty relay. However the book nor the owners manual tells what relay is what. They are numbered K1 through K8. Can anyone tell me which each of the relays are for? Any help would be appreciated. I also checked the system for proper freon pressures and they are ok. If power is put to the red wire with the black stripe at the pressure switch the compressor will come on and run normally.Thanks so much,KABUSAF.
August 28, 2009
  Followup from the Pelican Staff: Did you check the continuity of the low pressure switch? A/C problems are very complex, there are a lot of components that can fail and leave you stranded. I would check the power to the A/C clutch too to see if the problem is with the clutch itself. - Wayne at Pelican Parts  
e30dan Comments: 1990 e30 ... I had high idle because the circular plate inside the throttle body was not closing all the way even with all the tension removed from the throttle cable. Replaced the throttle body with one from pick-n-pull for about fifty. Problem solved.
August 22, 2009
  Followup from the Pelican Staff: Thanks for the additional info. We appreciate it.
- Nick at Pelican Parts
 
chris Comments: Hmimi1pd, i had the same battery issue with my '86 325i, put a voltmeter between the negative post and earth. With the key off there was something drawing power, started pulling relays under the hood until it dropped and it was the K6? not sure now relay in the fuse box - one of these square black ones. Problem fixed. Find a friend with a voltmeter, you have to switch it to measure resistance.
July 25, 2009
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
JP Comments: My wife just bought a '90 E30 318i auto. It is an immaculately kept car 130,000km with great service record. It is now idling at about 1500rpm and creating vibrations when in drive and stationary. I presume that the vibration is caused by the idle speed. What should it idle at? Read your article and will look at the hoses, any other suggestions.
July 24, 2009
  Followup from the Pelican Staff: If you idle is surging you should look for a vacuum leak. The vibration could be caused by the vacuum leak or a misfire. The vacuum leak is a good place to start. - Nick at Pelican Parts  
ETRE30 Comments: Pelican Staff, I have an 89 325i, just did an oil change and spark plug change and now the car starts up and idles erratically and the whole car shakes for a minute until it warms a little. It has 174,000 miles and a top end rebuild at 150k. Plugs that were removed looked normal with no corrosion or gunk whatsoever and before the oil change and spark plug change it ran smooth at all rpms, including idle. Am I misfiring? the car seems like its going to stall out and then the rpms pop back up to about 1200 back to 500 and in between. Please help
July 21, 2009
  Followup from the Pelican Staff: Honestly, it sounds like you bumped a vacuum hose when you were in there. Recheck all the hoses and/or remove some of the vacuum hoses to see if that makes a difference. If removing the hose makes no difference, then you probably have a leak somewhere. - Wayne at Pelican Parts  
NickB Comments: Thanks, this is brilliant - I've never read such a succinct description of not only what the throttle position sensor and the idle control valve do but also how to test them with a multimeter. A very useful article in all details, as are you pelicans! Do you live in England and can I buy you some fish??!
July 15, 2009
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
janna Comments: thank you Pelican Parts, my BMW 2001 530 was shaking at idle; mechanic tells me it is a weak engine mount and that it is normal in a car this age, we pop the hood and I check the vacuum hoses in front of mechanic - one has a huge hole in it - problem solved - well one problem - time for a new mechanic.
July 7, 2009
  Followup from the Pelican Staff: Indeed, there are a lot of shade-tree mechanics out there. Vacuum hoses are the #1 culprit of problems like these - he should have known that.- Wayne at Pelican Parts  
rob320 Comments: I have a E36 M52 engine with an idle that will go from 1500 to about 750, the idle will usually be 1500 when I stop then slowly drop to 750, the ICV has 3 pins, i get 12V on centre and 1.4 on one side and 2.6 on other, the voltages on the outter pins swap when the trottle is opened. I suppect the problem is either the valve or the ECU of maybe TPSany idea where th efault might be?
June 12, 2009
  Followup from the Pelican Staff: What year is the car? Did you pull any codes? Problems like these are typically vacuum leaks that can be easily and cheaply fixed with new intake boots. I'd check there first. - Wayne at Pelican Parts  
e30dan Comments: I just had a head gasket job done but now the car idles around 2000. Any idea what it could be?
June 6, 2009
  Followup from the Pelican Staff: Yes, this might be a vacuum leak somewhere. I would check all of the hoses and intake manifold vacuum to see if there is a leak. - Wayne at Pelican Parts  
Pablo Comments: 95 318is The care has an idle problem when car is both hot and cold. Idle jumps from 900 to 1200 then down to 600. Not constant, but sporadic. Had a 1224 code and replaced the MAS and the throttle position sensor. No luck. Suggestions?
June 3, 2009
  Followup from the Pelican Staff: Yes, this is a classic vacuum leak problem. I suspect there is a hose loose, or a crack that you just can't see until you squeeze it. - Wayne at Pelican Parts  
Maxxbh628 Comments: Hi, i just bought a 89 325i, i stopped for gas on the way home from purchase and the car just died. i tried to start again and it would start but will not idle with out foot on the gas. i popped the hood and saw the oil cap was off! it was sitting near the passenger back corner of the engine bay.checked the oil and it had almost a half a quart spilt during the trip.... the problem still persists even with more oil... the car did not over heat but there was a decent bit of smoke coming out. i was thinking maybe oil had spilt in the valve or the body or gotten into the spark plugs... i really have no idea please help
May 10, 2009
  Followup from the Pelican Staff: If the oil cap is off, then the car will not run correctly because there will be a huge vacuum leak. By the way, I have made a similar mistake before, and it's indeed a HUGE pain to cleanup (we all make mistakes from time to time). I would check your sensor boots and vacuum hoses for a vacuum leak - what you're describing is classic "vacuum leak syndrome". - Wayne at Pelican Parts  
mimi1phd Comments: deara red3rick,
Does that mean they both need to be replaced/repaired at the same time, or, and please tell me no, the hose replacement should correct it! My glove box has been locked for 15+ years due to lost key.
Additionally, if you know, I have replaced battery 3 times in last 8 months. It gets charged, and if i don't drive or start the car everyday, it goes completely dead. Last guy said he removed fuse for lighter and antenna, the latter being stuck in medium position, unable to go down or up. I happened to have taken the ash tray out the day before he "discovered" it was the problem leak/short! I don't think that is it because it had been working just fine. One guyu sid he rewired "the whole thing" but again, the car was dead in two days. I am having a hard time dealing with the frustration. So very annoying/stresful. Once the battery/idle work, she's still the ultimate driving machine. I'm going to do some serious praying. again, thanks for your input. it helps! xo
May 1, 2009
  Followup from the Pelican Staff: I'm not sure what your problem could be, but for all the cars I drive sparingly, I install one of these Battery Tender devices, and it works great! http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search.cgi?command=show_part_page&please_wait=N&make=POR&model=911M§ion=ELgage&page=6&bookmark=25&part_number=DEL-021-0123 - Wayne at Pelican Parts  
red3rick Comments: There are two parts to the idle system on some E30s - one under the hood a valve and one above the glove box a circuit card.
April 23, 2009
  Followup from the Pelican Staff: Thanks for the additional info. - Nick at Pelican Parts  
mimi1pd Comments: this sounds exactly like my 86 5-speed. she only has 79,500k on her, practically a baby, however she has always had to stay outside. I love how she drives, especially on the open road, where i have been known to take liberties with the speed limit.
Would there be any reason to go into the glove box? my feeling is that it is just the hoses, as you describe above. What do you estimate it should cost, how long it should take etc. i just got billed $140 for a Diagnosis and battery charge, which he did two times, however, i didn't drive it enough to keep it charged. he said there was nothing else wrong with it, but he couldn't do anything about the idle problem without getting into my locked glove box. lost key. nice man but it sure seems expensive for what he did. what could he have done to charge that much?
i am so happy i found you, and will try to get a friend to try your suggestion first. thanks very much. xoxosylvia flinn
April 18, 2009
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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