High idle on cold starts, only when moving or revving

[JGood]

The car is an 87 325is, basically stock m20. When I start it, it will idle fine, but if i give it gas it will go to 2k then slowly drop down after 5-10 seconds. It does this until it's warm (5 minutes or so)

Wierd thing is, I can coast downhill and that will jump up the idle too, with no throttle input. It's like it's taking the speed sensor signal from the diff and increasing idle because of it. I don't know how that sensor integrates with Motronic though.

Any ideas?

[jlevie]

That could be a sticking throttle body or cable, or a sticky ICV. The clue as to which is determined by grabbing the throttle body arm, opening the throttle, and then returning it to the idle position. If the revs stay up, the ICV is sticking. Otherwise the problem is with the throttle body or cable and you find out which by disconnecting the throttle cable from the throttle body and repeating the test. If the throttle body is binding, you'll feel it.

[nando]

there are 3 systems that affect the ICV

-TPS - check for adjustment with a closed throttle, should "click" when the throttle hits the stop.
-VSS - the ECU will turn on the ICV when it sees the car is no longer moving (or below some threshold).
-CLT sensor - the ECU adjusts the idle valve during warmup to let in more air

other than the ICV itself, those are the things you'll want to look into. Usually, the valve itself is bad and not something else related to it. But you never know..