528 with its own mind

Hi all. I have had this 84 528 Euro import for quite some time now, and I can honestly say after the investments that I put into it I am still thrilled with it. I've replaced everything short of the engine and transmission since Ive owned it (take that back the head blew 6 months ago). Now its doing something very odd.

The engine revs to about 1500 rpm and then drops back down, doing this consistantly in park or neutral....basically anytime it comes to a stop. Ive checked the obvious. Someone last night told me it could be a possible vaccum leak, I think its a electronical sensor somewhere that would beyond my finding. :screwy:

Any suggestions would be nice so I'm not chopping my legs off to have an import shop find it.

Thank you!!

To clarify a bit, it revs up to 1500 and then goes back down, then up and down up and down....doesnt ever stop. Doesnt matter how much I drive it, its consistantly does it :banghead:

These engines are notorious for having a "hunting idle", sounds like it's going into a closed loop, going up to 1500...coming back down, then up again.

Maybe an oxygen sensor?

http://www.bmwe34.net/e34main/trouble/hunting_idle.htm

Look at that link and see if it helps.

Ended up being something with the ICV, did some cleaning on it and rewired it, pooof problem solved...ive looked at the thing a million times but taking it off and putting it back seems to be the fix. Thanks for all the emails and the reply much appreciated.:grinyes:

What did you use to clean it with? Since mine does the same thing.