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Pelican Technical Article:

Reading OBD-II
Fuel Injection Systems

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

     This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
 
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[click to enlarge]



Figure 1


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Figure 7

 

     Starting in 1996, automotive manufacturers began equipping all new cars with a new federally-mandated emissions diagnostic system called On-Board Diagnostics, or ODB-II.  An earlier version, called OBD-I is implemented on 198X-95 BMWs, but is not as advanced or easy to tap into as OBD-II.  For more information on reading Fuel Injection fault codes on the OBD-I system, see the Pelican Technical Article, Reading Fuel Injection Fault Codes.  The OBD-II system was developed primarily to help combat emissions problems by quickly and easily identifying failed components of the fuel injection system.

     In the past, it was prohibitively expensive to purchase the equipment required to read and process the information from the OBD-II interface.  However, scanning tools and software has come down significantly in price, enabling just about any home mechanic to read, record, and monitor the entire fuel injection system.  There are many scanner tools available today, and quite a few that allow you to monitor the OBD-II interface on a laptop computer, or even a PocketPC.  These scan tools save you time and money by allowing you to diagnose potential problems without repeatedly taking your car to your local mechanic or dealer.  I have heard people gripe and complain about how today's modern cars have become so complex that the average do-it-yourself mechanic can't figure out what's wrong with the car.  I don't buy into that - the OBD-II cars are much easier to diagnose and repair than earlier models primarily because the computer will tell you exactly what is wrong and takes the guesswork out of complicated troubleshooting.

     For my own garage, I chose the laptop-based software from AutoEnginuity, available from Pelican Parts.  The package comes complete with an OBD-II adapter, a serial cable, and software that is installed on your Windows laptop computer.  Installation and setup is very easy and is as simple as plugging in the connector and cable into your BMW's OBD-II port.  The OBD port is located near the driver's foot well, on the lower left side (Figure 1).  Simply flip open the cover, pull off the plastic connector cover, and plug in the adapter.  Run the cable over the steering wheel and plug it into your laptop, which can fit on the passenger's seat (Figure 2).

     The AutoEnginuity software has several different screens that allow you to monitor the system in real-time.  Figure 3 shows the live data screen, which can be customized to show any one of the OBD-II sensors.  You can output oxygen sensor voltages, engine RPM, coolant temperature, ignition timing advance, intake air temperature, or a host of other sensor values.  The software allows you to capture and freeze the data or log it to your local hard drive.

     Figure 4 shows the Dashtop screen, which allows you to monitor various sensors in a analog format.  This is very useful for when you are driving, and you want to quickly glance at the "gauges" to get a quick idea of what their values are.  This screen functions very similar to the sensor screen with the digital readouts.

     The live data graph screen is shown in Figure 5.  This allows you to monitor two sensors side by side, and graph their changes with respect to each other.  This particular screen is very useful for tracking down intermittent failures and can be set to run for extended periods of time while you're attempting to recreate the problem.

     There is a separate screen specifically tailored to monitor your oxygen sensors (Figure 6).  The oxygen sensor (also known as the O2 sensor) is probably the best indicator of your engine's health and performance.  The oxygen sensor changes its value based upon the amount of oxygen present in the exhaust.  This percentage is directly related to the air/fuel mixture that is fed into the engine's intake manifold.  If the mixture is too rich or too lean, the engine will not generate an ideal fuel burn.  This results in increase emissions, and a decrease in power.

     The OnBoard test results screen (Figure 7) shows the results from several diagnostic evaluations of various system modules.  The system monitors the engine in real-time for misfires, fuel compensation, and comprehensive component monitoring.  The results of the tests are shown on the right.

     In addition to the full capabilities of the OBD-II scanning software, the AutoEnginuity package includes a neat tool call SpeedTracer. This utility allows you to estimate various performance characteristics of your BMW by monitoring the sensor output from the OBD-II computer. In real-time, the software acquires the engines RPM, the car's speed in MPH, and the ambient temperature. Mixing that with known characteristics of the car from pre-configured profiles stored within the software, the computer can accurately estimate performance characteristics like horsepower and torque. Using the real-time monitors, the software can measure 1/4 mile times and speeds as well as 0-60 MPH performance. All of the stock OBD-II compliant BMW cars are already pre-profiled in the software.  In addition, you can enter compensation variables into the software (temperature, humidity, altitude), to help correct the horsepower results to ensure accurate and repeatable results.  If you have modified your BMW, you can change the default values specifically to fit your car.

     The SpeedTracer tool is definitely a fun tool to play around with. However, like the big roller dynos, the horsepower figures are somewhat subjective.  Driving ability and habits and may slightly skew results in the software.  As with the traditional dyno, SpeedTracer is best viewed as a comparison and tuning tool.  Although not as precise as a real dyno, you can test your car indefinitely, and use it to determine if you’re gaining any horsepower from minor modifications and tweaks.  As with the big dyno, the results are often dependent on environmental factors, so you should only really compare numbers from same-day runs.  It’s also highly dependent on the characteristics of your driving, including the speed at which you shift through the gears. Another downside, of course is that you need a laptop computer to make the whole system work.

   
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Comments and Suggestions:
T Comments: Alright. So I put my car in the shop and they replaced the connector hose that is on top of the motor near the fire wall. This stopped the misfire during cold starts. I was still getting codes p1189 p1188 and a new code p0150. I then took the car back to the shop to makes sure they put the part on correctly. They ran another smoke test and found that it was leaking from a bolt being over tightened, so I put a new valve cover on it. After this fix the only code I have is p1189 and cant seem to find the last problem/leak to save my life. I am almost there so any help would be great.
August 10, 2014
  Followup from the Pelican Staff: I need the last seven digits of your VIN to see what the code refers to. - Nick at Pelican Parts  
Kingy Comments: sorry I replaced the COILS
August 7, 2014
  Followup from the Pelican Staff: Ok, got it. - Nick at Pelican Parts  
Kingy Comments: Guys I have a 2003 E53 X5 4.4i, which is the best kit to buy for a bush mechanic.and a beginner I assume its OBD11..??? By the way on you chat above you talk about missing when cold. Vacuum normally misses at idle hot or cold moreso hot My 4.4 was missing cold and I replaced the coild and it goes like a rocket.Can you help with which kit please
August 7, 2014
  Followup from the Pelican Staff: Kit as far as scan tool? It depends on what your budget and need is. Some people can get by with a code reader, some people need an advanced tool. - Nick at Pelican Parts  
T Comments: Alright so I checked for vacuum leaks and for none. I replaced the CVV and did not fix the problem. Like I said before I have replace MAF, both pre cat o2, spark plugs, fuel filter, MAF boot, and examined all the other hoses for damage. I have yet to find the solution. I will most likely put my car in the shop, unless you can thing of anything else for me to do. I sprayed carb cleaner all around vacuum hoses to check unseen leaks but no luck. Thanks in advance.
August 3, 2014
  Followup from the Pelican Staff: Are you still chasing fault codes or the engine misfire? If an engine misfire. I would check spark, fuel and compression on all cylinders.
- Nick at Pelican Parts
 
T Comments: Thanks Nick! I will check those things. What do you think about it being the fuel filter?
July 29, 2014
  Followup from the Pelican Staff: I haven't seen many plugged fuel filters. Usually they are not the root cause. - Nick at Pelican Parts  
T Comments: I have a 2000 528I bmw that will mis fire when started up cold in the morning. After I gets warmed up it stops misfiring. I also have the code p1189 and p1188. Misfiring code to come up as pending when first started by eventually go away. I have replaced the MAF. and checked all the other hoses to the throttle body for no damages. I did hook the obd II up and seen that the o212 sensor was steady unlike the other ones. Should I replace this or keep checking for leaks? where else could I Check?
July 29, 2014
  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
 
Johnmarston Comments: I have a 1996 bmw 328is manual and it is due for renewal and a smog check here in Ca. When it was smog tested, it passed emissions but only failed the OBD system check. My car had been sitting for a while and had its battery die. My mechanic told me to restart this system I had to put my car through a driving cycle. He said basically just drive it on a freeway for about 30 minutes. What is this driving cycle and how do I have the OBD II reactivate? Any advice is greatly appreciated
May 7, 2014
  Followup from the Pelican Staff: A drive cycle is what is required by your vehicle to run all of the non-continuous emission monitors. Usually letting the vehicle idle for a minute, then driving it for a while will run them. You can check with any ODB II scan tool to see if they have ran and passed. - Nick at Pelican Parts  
JOEYB1960 Comments: need help terrible bad i have a BMW 1999 328ic e36 i went to o reillys to have them scan the obd2 to see if there gitting the same codes i was thay did the same 4 codes # 1 p1189 fuel con bank 2 sensor 1 #2 p0173 fuel trim bank 2 #3 p1188 fuel con bank 1 sen 1 #4 p0170 fuel trim bank 1 ok thay told me i needed 02 sensors so i got 2 new sensors started it up ran it the same 4 codes thay gave me a list to go down this is what i did i put new o2 sensors a new pcv/ccv valve and all new vacume lines and cleaned intake lines i even put a new o ring on the oil dip stick THATS RIGHT THE SAME DANG CODES 4 OF THEME SO WHAT THE HECK DO I DO NOW NEED YOUR HELP IN A BAD WAY WHAT PARTS DO I NEED TO ORDER FROM YOU AND HOW FAST CAN I GET THEM JOSEPH BAUGH 623 234 1732 0r joeyb1960@gmail.com help
February 3, 2013
  Followup from the Pelican Staff: It's nearly impossible to diagnose a problem like this over the Internet, unfortunately. The first thing I would do is get the PEAKE Research diagnostic tool and plug it into the card to see if you can get a better code than the ones that they read at your local auto parts store. In general I would guess that these codes might be caused by a vacuum leak somewhere in the intake. Your car is now 15 years old, and I predict that some of the field are beginning to wear out. The default action of replacing oxygen sensors is a common diagnosis by sales reps at local auto parts stores. It sounds like the car may need some professional diagnosis have a qualified mechanic in order to get this problem fixed - Wayne at Pelican Parts  
serge Comments: I have a 2003 BMW 530I the check engine keep coming on. I clear it a few times still back on. The computer reading is code P0171 / P0174. Can anyone help with this problem
February 29, 2012
  Followup from the Pelican Staff: This is a fuel trim issue. Could be a vacuum leak or a bad mass air flow sensor. - Nick at Pelican Parts  
Brakey Comments: What Software and laptop connector kit is this. This is exactly what I'm looking for.
January 4, 2012
  Followup from the Pelican Staff: That is the Autoenginuity tool:

http://www.pelicanparts.com/catalog/shopcart/101P/POR_101P_PRJ029_pg1.htm - Nick at Pelican Parts
 
allnalevels Comments: everytime i try to raise the engine, the metre goes up to 5 or 6, comes down and go up again.what could the problem be. i have tried all but to no avail. pls help.the car is e36,manual,91 model
October 12, 2011
  Followup from the Pelican Staff: Maybe you have a slipping clutch? - Kerry at Pelican Parts  
ph Comments: more detail: for my obd ii ELM 327 with 20pin adapter,possible to works with 11/1993 properly or can't
June 27, 2011
  Followup from the Pelican Staff: No it is not going to work - Kerry at Pelican Parts  
ph Comments: I still need obd ii for bmw 1993 it possible to operate or with adaptor
June 27, 2011
  Followup from the Pelican Staff: No you have to get the right code reader for your car - Kerry at Pelican Parts  
lawdog 62 Comments: Wayne I brought used e36 dme 1997 318 with same part number from southparts. The car it was taken from was running. I put in my bmw and nothing. The code fault reader/ reset reader EWS message. How do I fix problem? I have a new ews unit aready coded for my car. How long does it take recode the dme?
January 14, 2010
  Followup from the Pelican Staff: You have to have a scan tool capable of aligning the EWS and DME - Kerry at Pelican Parts  
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