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Hi.. I have read a lot of about idle speed motors etc but I have different problem. (Car is EC5A 1997 and ~120 000km driven)
When engine is warm (i have driven at least 10km) and I stop the idle speed lowers from 750-->500rpm. Ecu lift up the idle right away, but it may drop again.
Right after that if I press VERY slowly gas pedal, the car "cuts" (sound from exhaust: "pröt pröt") until I reach like 2000rpm the engine speed jumps right away to 3000rpm (unthought I do not press more pedal)
If I press gas pedal hard it doesn't stall at all.. no "pröt pröt" sound....It takes very fast revs and works totally ok.
I have changed new plugs but no effect.( old plugsphotos: http://harrinkuvat.1g.fi/kuvat/vr4/tulpat/ )
... 3 of plug holes were half away full of oil. I know the oil seals leaks and we opened rocker covers and put some sealing kit to the seals and tightened more covers ( not more that 100km driven after that) And i have ordered new seals too...
Also i changed thermostat because it was leaking inside (seal was broken because it was old) Now engine is 82 degree celsius as it should be.
But those 2 repairs had no effect to that idle and not good engine running while it's warm. Cold engine and the driving is good. No problems then, only at idle at warm engine and after that small "cutting / missfire or stalling".
Is it oxygen sensor failure and idle stepper?
Or ignition coil problem?
Vacuum leak?
Car has 3" cat back exhaust and Forge by-pass valve. Tiptronic car.
When engine is warm (i have driven at least 10km) and I stop the idle speed lowers from 750-->500rpm. Ecu lift up the idle right away, but it may drop again.
Right after that if I press VERY slowly gas pedal, the car "cuts" (sound from exhaust: "pröt pröt") until I reach like 2000rpm the engine speed jumps right away to 3000rpm (unthought I do not press more pedal)
If I press gas pedal hard it doesn't stall at all.. no "pröt pröt" sound....It takes very fast revs and works totally ok.
I have changed new plugs but no effect.( old plugsphotos: http://harrinkuvat.1g.fi/kuvat/vr4/tulpat/ )
... 3 of plug holes were half away full of oil. I know the oil seals leaks and we opened rocker covers and put some sealing kit to the seals and tightened more covers ( not more that 100km driven after that) And i have ordered new seals too...
Also i changed thermostat because it was leaking inside (seal was broken because it was old) Now engine is 82 degree celsius as it should be.
But those 2 repairs had no effect to that idle and not good engine running while it's warm. Cold engine and the driving is good. No problems then, only at idle at warm engine and after that small "cutting / missfire or stalling".
Is it oxygen sensor failure and idle stepper?
Or ignition coil problem?
Vacuum leak?
Car has 3" cat back exhaust and Forge by-pass valve. Tiptronic car.