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Re: 1988 E30 M3 -- Hunting Idle Problem! (archive)

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Posted by CFL on November 02, 2000 at 16:26:42:

In Reply to: 1988 E30 M3 -- Hunting Idle Problem! posted by Avory on November 02, 2000 at 15:13:21:

When cold or after starting my m3, it idles and runs perfectly without any hesitations. However, after driving several miles in the city - stop and go. The idle seems to hunt during red lights. Does anyone have any thoughts for repairing this problem?

Yes. Your ICV (idle control valve) went south and when it did, it also damaged the DME (digital motor electronics) portion that controls the ICV.

In other words, you need both. Do not replace the computer first or the bad ICV will fry it again. Replace both items at the same time. Here's some info on how to test it, unfortunately the ICV is buried in our cars under the throttle bodies. This is from a fellow M3 owner from Spain:

How can we check our ICV's/DME's?

1) Put the car in a silent place and open the hood

2) Turn the ignition key to the position II, but DON'T start the

3) Pray to God ;-)

4) Get your head in the engine compartment and try to listen
to the ICV(it's hidden under the intake pipes #2 and #3). If you
hear a buzzing coming from the ICV and you feel a vibration
when you touch the ICV hoses, then you're lucky, it's alive (and
the DME, obviously).

5) If you don't hear the buzzing, then check the ICV:

5.1) Turn ign. key to zero again.

5.2) Unplug the black connector that is between the intake
pipes #1 and #2, close to the injectors rail. Forget the upper
part of the connector. We are going to work with the lower part,
the one that shows 3 flat pins. This wire goes directly to the ICV.

5.3) Take the ohmmeter. The resistance between the center pin
and any of the other two pins should be aprox. 20 ohms. In other

Rcenter- Rright : aprox. 20 ohms. (1)
Rcenter- Rleft : aprox. 20 ohms. (2)
Rleft - Rright = (1) + (2) = 40 ohms.

If one of those values is lower than 10 ohms, that ICV will kill your
DME if it has not been already done.

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