MADSKOTZMAN

I have a 4 cyl 2.o litre 8 valve (1994) British coupe, and a couple problems with it...
First of all im having trouble finding out the bosch fuel injection type (think it might be KE Motronic).
Secondly a strange problem with warm up driving. When starting engine cold it starts and runs smooth for about 3 - 5 min, then all of a sudden the revs drop and then pick up, the smooth idle being replaced by a lumpy one as well as interrupted power while driving. The problem completley clears itself as the engine heats up to normal operating temp and doesnt return until cold again. My first suspicion being that old ISV that so many people have trouble with. However this is not stuck, it appears oscillate rapidly opening and closing the valve. (Is this the correct operating procedure?). What i did notice though is that when the engine is running rough and you disconnect the ISV it seems to clear the problem but the engine idles to high. Does anyone have any suggestions???

YucatanAudi

Also check for vacuum leaks in the hoses.

When you say "disconnect the ISV" are you pulling the wire or removing the ISV to leave the hoses open? (when it idles too high)

If you are disconnecting the wires, then you are decreasing the amount of air passing through the ISV, which can lead to a richer mix - therefore, the logical result of idling too high.

Yes, the ISV is supposed to oscillate rapidly, but you don't know that it is producing the result intended by the ECU by looking. That's why cleaning and lubricated is recommended - and very easy - as a first step toward tracking this down.

MADSKOTZMAN

I was pulling the wires from it but it didnt clear the problem every single time. Vacuum leaks have been checked for and all is normal. I have already spayed WD40 into it however i am aware that carb cleaner is far better and will give it a try. Also, should the ISV ever 'kick out' once the engine has heated up or keep buzzing away the whole time the engines running?

YucatanAudi

WD40 is a solvent, not really a cleaner or lubricant. When you have time, take it off, spray it with Carb or Brake Cleaner (many prefer Brake Cleaner as it is less likely to eat plastic) until the fluid runs out clear. Likely it will be real black at first.

Let it dry or blow it out completely. When dry, spray good with Silicon Lubricant Spray (not WD40). Let dry completely and install.

That just might do it.