From: darling@simlab.arc.nasa.gov on behalf of Dave Darling [darling@simlab.arc.nasa.gov] Sent: Wednesday, April 28, 1999 4:21 PM To: John Nguyen Cc: pelicanparts@csi.com Subject: Re: 914 Fuel Injection Help >I read many of your earlier posts about rich FI system. >I've been having some FI problems now and can't seem to trace the source. Hopefully my own problems are not related to yours. I chased my rich-running problem for a week before I thought to check the valve adjust- ment, which is how I found the dropped seat. OK, first steps first. You mentioned that you have replaced some of the ignition stuff. Have you checked to make sure you're getting a good spark from the coil? How about from the plugs? Timing and dwell check OK? Unplug the tach and see if the car runs any different. The tach is driven by the points signals and a messed-up tach can mess up those signals. Next, the valves and possibly a compression test. The compression test will show you if something is not sealing in the top end. If I had kept trying until I got the tester threaded into the #4 spark plug hole, I would have found zero compression (or darn near) on that cylinder and been able to stop wondering. The valve adjustment can tell you a seat has dropped. Not a common problem, except for my car and one or two others. It's easy to see when it happens, because most of your valves will be some- where near the specified clearance (0.006" most valves, 0.008" for sodium- filled valves like 2.0 exhaust valves) while one will have about 1/8" of clearance. 0.125" is about 20 times too big, and is pretty obvious. The tip of the "relaxed" valve will sit noticeably lower than the others on that head. >On cold starts, she starts right up, no problems. after 30 seconds or so, >she dies and >i have to crank it up again. cold idling is really bad, she will die if i >don't give >gas.. After about 10 minutes or so, when the engine is warmed up, the >idling is better, >but not much. The tach needle goes from 500rpm to 1200rpm. I seems to >sputter on the >highway around 2500 to 3500 rpm. At rest, the idle is unstable and i >smell alot of gas. >I have checked the ignition, replaced points, condenser, coil, plugs, wires, >I also replaced the Pressure sensor w/ a rebuilt unit and all the vaccumm >hoses. >I checked the resistance on the throttle switch it seems to be okay. >I also unplugged the cold start valve to see if it was stuck no change. > >How did you find out that you had a dropped valve seat? >what else should i check? >Any suggestions? >I downloaded the FI troubleshoot guide from PP, 914 Network, and some >Rennlist,Porschelist >Opps! forgot to mention that it's a 1973 2.0L Hmmm.... That's a bit tough. My first thought, due to the varying idle, is that the mixture is too lean. But if you're smelling gas, that does not sound like a lean mixture. OK, is your aux air regulator open when the engine is cold? Is it closed when the engine is warm? It must do both of those things. Check to see that the AAR is plugged in. There's a red wire coming out of the bottom of the can that connects to a white wire from the engine wiring harness--or was it the FI harness? Make sure the "can" has ~0 ohms resistance between it and the battery ground terminal. Check the battery (+) and ground terminals for corrosion and contami- nation. They should be shiny. Clean with a wire brush AFTER you have dis- connected the battery. Check the multiple ground point at the rear of the top crankcase seam on one of the through-bolts. Clean it up good, make sure the connetors are on there reasonably tight. No broken wires are allowed! Check the resistance of the head temp sensor--check from its connector (unplugged) to a ground. Should be 1500-2500 ohms cold, <300 hot. Maybe <100 hot. Warm the car up (drive it for ~10 minutes), let it idle for 2-3, and then remove and check the color of the plugs. If they are black and sooty, you're running rich. If they've got whitish-grey deposits, you're running lean. If they are tan-brown, the mixture is OK. Plugs should be the same color as each other, if they are appreciably different then you have something pretty odd wrong with the FI system. (Trigger points, wires, injectors, etc.) If the idle mixture is OK, I'm not sure what to say on the hunting idle and gas smell. You can also check the mixture of the engine while it is running but NOT at idle. Get it warm, drive for a couple of minutes in the RPM regime where you're having problems, then TURN OFF THE MOTOR while it's running. Do not let the revs drop to idle first. Coast to a safe parking area, then pull the plugs and check the colors. Check through the troubleshooting articles, particularly Kjell Nelin's guide from the 914 Fan Page, . If you get all the way to the end of the article, and the FI passes all of his tests, then I'm not sure what else to tell you. Good luck! --DD Dave Darling 74 914 2.0 (decapitated) darling@simlab.arc.nasa.gov "OFF WITH ITS HEADS!"