Sorry for the length of this post, but I want to make sure anyone interested in helping has all the information I have...
I have a 1991 Passat with 287K km on it. I've been having problems with it for some time. Used to be, it would start without a problem, however if I drove it any distance I ran the risk of stalling and not being able to start again. Let it sit a while, car starts. A friend of mine worked in a VW service department up to the late 80's and we tried to pinpoint the problem. Finally, we gave up and brought it to the local dealership. The computer said it has a bad oxygen sensor and bad knock sensors. C$500 for parts and at least 3 hours at C$70 for labour. And that was just to clear the ECU so they could diagnose the problem.
It ran worse than ever once it came out of their shop, even though they only hooked it up to the computer. I managed to limp my way home, but the car hasn't started since.
I don't understand how the oxygen sensor or knock sensors have anything to do with starting. It's my understanding that they only have an effect on a running engine. Both parts are quite expensive, so unless someone can explain how they effect starting, I'm not replacing either until the car starts :)
The car turns over just great (although I've had to recharge the battery a few times). The starter motor is good, I replaced it not too long ago. The car sounds like it's really trying to start. When I'm trying to start it, it often (but not always) sounds like it's firing on one cylinder. Sometimes, when I'm first starting to work on it, it will start but it only runs for a few seconds and very poorly.
I think I've fixed the oxygen sensor problem, the ground connector on the cable from the oxygen sensor to the ECU was broken. I cannot find any other circuits that are broken.
We've attempted to correct the previous problem by adjusting the airflow sensor plate. Since it's been stuck in the driveway, I've spent a lot of time adjusting it and trying to start the car (1/4 turn, try to start car, 1/4 turn, try to start car ...). So, that's probably right out of whack at this point.
I've had the ignition wires on and off more times than I can count, doing various checks that have been suggested to me. I'm not sure anymore if they are still in the right place. Here's how they are placed on the distributor cap now:
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