M3 high idle

[vertbmw]

Hi all, my car picked up a high idle recently. Stock s14 with cold air intake and exhaust. Starts and idles fine at 800rpm for a minute or two if you don't rev it then it creeps up to 1100, if you rev it then let it drop it will go to 1100. Sprayed carb cleaner to check for intake leaks did not find any, have not cleaned the idle air valve it looks like a pia to remove. Anyone have this issue

[einhander]

If you found no leaks, it could be your DME. Less serious could be intake gaskets as they break down over time. Could just need to have your base idle set, as well.

Would say throttle cable clips could be shot, but if it is hunting that may not be the case...

[vertbmw]

How do you set the base idle? Just remembered when it first started it was intermittent. If memory serves the throttle was hitting the stops and the cable had slack so don't think it is the clips.

[kickinindian]

does the s14 have an icv? my M20 did that same thing and it was a sticky icv

[NZM3]

Hi,
If you open the hood then turn the key to the on position you should hear a light buzzing noise from under the inlet manifold, this would indicate the ICV is operating correctly.

No buzzing noise would indicate problem most likely the ICV transistors in the DME require replacing along with the ICV.

Next item I would check is the throttle position switch a click should be heard when moving it the throttle shaft from idle position and test with a ohm meter quite common item to cause high idle due DME not getting idle signal.
Dave.

[vertbmw]

Thanks for the replies, the icv buzzes but very faint, not as loud as my 325. The throttle position switch clicks right as throttle opens the contacts between pins 18 and 2 open, pin 3 does not change when throttle is opened.

[fronton]

Most likely a sticking ICV. I'd replace it regardless for piece of mind. In fact I am doing the same this weekend.