Problem returned

[MonkeyBoy]

About six months ago I thought I may have solved the problem with my 90 C4 - the engine would die and not hold an idle once "push-started". I think the issue was that my mix would get way too rich due to a faulty head temp sensor and/or 02 sensor, both of which were replaced. Yesterday the problem came back, but it goes away much more quickly than last time - when I take my foot off the gas and let it stall I can restart it and the problem usually goes away. I also notice that I smell a lot more fuel when I start the car in the morning. What else (electrical) effects the fuel mixture?

Also... Today my seatbelt and airbag lights will not go off when the car is on. The airbag light blinks for a split second about 5 seconds the car is started, but doesn't go off. I'm now wondering if my voltage is too low and the DME is unhappy and is causing the fuel problem. The engine turns over immediately though.

Here are some other variables:

My oil was changed recently and they overfilled it. I don't see any smoke at startup so I don't think I'm fouling my plugs. I haven't drained it because I don't think it's too overfilled.

My gas tank was extremely low the night that this happened - warning light was on for 20 miles. Perhaps some tank crud made it through the system - but I still think it's an electrical problem.

Any ideas are appreciated.

[twin plugged targa]

Geeze, Lot of variables and symtoms there dude!
If you want to diagnose this intermittant fault , you are in for a possible long ride!.
It took me 5 weeks to find my bad distributor- I went from believing it was a damp related problem, then a voltage, to a temp. related and my wrench thought it was a Worn valve problem!.
I would suggest trying to rule out certain areas.
Get a good volt meter and load tester and check condition of Battery and Alternator.
Then work your way through each system from start to finish. Electrical (inc. grounds),Ignition system, Fuel, DME, DME harness and sensors.
The list may even go on!.
You may be lucky and find it quickly!. But with all of those symptoms- which may not even be linked! you may need some patience and a lot of help from these helpfull guys (with more experience/knowledge than me).
Hope this helps,
Rgds Ben

[Wayne 962]

Well, since your fuel was low, check the fuel filter and see what you have in there. I would replace it as a starting point. I have heard of various electrical problems like these, and they indeed are not too fun...

-Wayne

[MonkeyBoy]

Update - I had the car hooked to a Bosch hammer and it revealed an airbag sensor problem and also a previous mass air flow sensor problem. I also had the fuel filter replaced. I'll keep you posted if the power loss returns, which I fully expect.

[MonkeyBoy]

Problem returned again. I can rule out wetness as the car hasn't gotten rained on since. Also not the fuel filter as that was changed.

It seems to happen especially after a long highway ride when I slow down to 10mph or so.