Audi 80 Coupe Won't Idle When Hot

[jheritage]

Hi Guys... please can someone help; I am coming to the end of my teather with my 1994 2.0 16v coupe!!!

The car runs fine, however after I have driven it round parked up for about 20 minutes or so giving the heat chance to soak into the various components in the engine bay the problems begin. The car fires up fine but will not idle; it doesn't struggle then stall it just cuts straight out as if the ignition has been switch off as soon as you take your foot of the accelerator. It won't idle then until it has cooled completely. If you switch of the engine after a run and fire it up again straight away or 5 minutes later its absolutely fine.

Had a diagnostics check done but no fault can be identified. I am at a point now where I'm going to have to start changing various components of the fuel injection system to sort this problem out which could get very expensive. Any suggestions on what may be the problem will be very much appreciated.

Thanks

John

[Keith853]

I have a 93 16V Avant that occasionally displays the same symptoms. Initially I thought that it was something to do with the water temperature sensor. I came to this conclusion as the car would idle OK if I disconnected this sensor (one on the back of the head) However I have replaced this sensor, and the short connecting cable, but I think that the problem is still there although it has not shown the symptom since. I am fairly certain that the problem is sensor or injector related as it does idle quite well with the temperature sensor or the pressure actuator disconnected. This implies that mechanically the injection system is operating correctly.

My next check is to be the cold start injector. If this is leaking then the engine will be getting a lot of unmetered fuel that will stop it from idling correctly. The check will be to run the car up to temperature then stop it, remove the cold start injector without disconnecting it from the fuel line and see if it weeps.

I had a Volvo 240GLT with a similar injection system that would not restart if it had been run for a short while then stopped. The work around for this was to remove the fuse for the fuel pump, crank the engine until it started (momentarily) then reinstate the fuse and off he would go. The explanation for this was that the cold start injector leaked fuel that effectively flooded the engine so starting with the fuel pump fuse removed sucked out this extra fuel.

My gut feeling is the temperature sensor. If I have any other ideas I'll post again, if you fix it please post again.

[rooflessB4]

HI, have you tried the Idle control valve? This is a very common fault on Audi's! I had the same problem with mine recently, and was able to get away with cleaning it out with carb cleaner. If you contact martyn@partsforaudi.info he will be able to advise on price and availability for a replacement. He will also send you diagrams and part no.s to help you locate it. If you're lucky, you may get away with a good clean. Good luck and let us know how you got on!