87 325is idles rough with A/C ONLY

Post Wed Aug 27, 2008 7:16 pm

It high idles with the ac on, shut the a/c off and the car idles back to where it should. Any ideas? Thanks

Post Wed Aug 27, 2008 11:58 pm

It's supposed to! The ICV can't respond quick enough if the aircon clutch pulls in, so the car might stall at normal idle.
There's a four pin connector hanging off the engine loom just before the ECU plug. The increase idle speed signal goes to the ECU by a pin in this connector. Disconnect it, and the idle will stay as normal.

Post Thu Aug 28, 2008 2:15 am

It is normal to ramp up to 2000 rpm? Wow. That seems high.

Post Thu Aug 28, 2008 9:13 am

Should only go up a few tens of RPM, not to 2000!
Pull the connector that I've mentioned apart, and see what happens then.

Post Tue Sep 23, 2008 12:27 pm

I am not sure what connector you are talking about, but I pulled the connector on the back of the idle control valve. When I do this the car then idles down. When I plug it back in, it idles up again. How do I diagnose a bad ICV? I replaced the intake bellows pipe and the other rubber hose off of the ICV. The large intake hose going to the throttle body had a nice 2 inch tear in the bottom. It needed to be changed, but did not change my idle issues.

Post Tue Sep 23, 2008 2:28 pm

Connector is a couple of inches away from the engine ECU, and comes out of the large cable that goes to it.

Post Mon Aug 17, 2009 6:09 pm

So we are talking about something under the dash then?

Post Mon Aug 17, 2009 6:23 pm

Brian, aren't you meant to be on holiday?

Post Mon Aug 17, 2009 6:28 pm

I believe he is, I am hoping someone else will know the answer to this. Thanks.

Post Wed Aug 19, 2009 6:21 pm

Anybody know where this plug and harness is located in the car?

Post Wed Aug 19, 2009 10:52 pm

Sorry, I need more info. Is this under the hood or under the dash. I thought someone said it hooked to the ecu, which I believe is under the dash. Thanks a ton for your help.

Post Tue Aug 25, 2009 9:51 pm

I see the ECU and I see the large bunch of wires going into it. But I do not see what controls the a/c. What color wires am I looking for? THe car is an 87 325is. I looked for a plug that is a few inches before the ECU, but no luck. Any pics of this? Thanks.

Post Tue Aug 25, 2009 10:00 pm

sept 2008-august 2009, flip thats one long running problem

Post Tue Aug 25, 2009 11:09 pm

Yep, I dealt with it until the end of the a/c season last year and then this year the damn thing did not cool at the start of the season. So, I tracked down my leak and now I would like to track down why the thing will rev to almost 3000 rpm when I push the a/c button.

Post Wed Aug 26, 2009 1:13 am

Fantastic, thanks man.

Post Wed Aug 26, 2009 6:59 pm

Does it actually attach to the ecu?