Help needed: Direction of ICV on '91 325i

[Ron ///Man]

Hi, All:

I've been fighting a really poor cold idle on my '91 IX for a couple of years. Once the engine is warm, it idles like a Lexus, but when it's cold, it bucks, runs rich, hesitiates, wants to stall, idles low (500-600), and is just unbearable...

Background: I've replaced the O2 sensor, AFM, temp sensors with brand new parts, and swapped ECU's with a friend. There are no intake leaks, The PO replaced the ICV with a new one. Sidenote, I just rebuilt the engine (with new block / pistons from BMW), and rebuilt the head, so I know compression is good!

Tonight, I went out to swap the ICV just to leave no stone unturned. I put my friends on, and of course, the car started and ran like crap. I thought to myself, who's to say that the ICV is installed correctly?? The PO replaced it, but maybe he put in it backwards!!! I swapped it around, started the car, and VIOLA!!! It ran totally awesome!!! Idled great, exhaust smelled 'normal'... no more bucking/hesitation/stalling!

Sooo, my question is, who can tell me which direction/orientation the ICV should have on the engine??? There's an arrow cast into the metal
body. Can someone tell me which way that arrow should point??? Mine pointed TOWARDS the engine (you could see it on the top of the ICV). When I reversed it, it now points towards the AFM (but you can't see it because it's now on the bottom side of the ICV). Can someone post a closeup pic of their ICV installed on their 325i?? I'd be able to tell from the pic which way it's installed.

Thanks !!

Ron ///Man

[olskool]

The arrow on the icv faces up and points toward the throttle body.

[Ron ///Man]

Thx for the reply. That's the way it was installed, and logically I thought it was correct, but thought I'd try swapping it around anyway. The fact that the car runs great with the ICV in the wrong direction should give an indication of what the real problem is, but it's not apparent to me... I guess it's back to square 1... I'll put it back in the 'correct' way and continue troubleshooting the crappy cold idle. About the last thing I haven't checked is the FPR. I'll pull a vacuum on it today.

[mikeedler]

I cant see why it would matter in which direction it is in. it is just letting a spec. amount of air escape past the TB. maybe your problem lies in the wiring and through moving it-- it made a contact again.

if it runs the "wrong" way, then just leave it like that.

[olskool]

^+1. I would leave it up side down if it works. It may be the wiring contacts. Try cleaning the contacts with some electrical cleaner.

[Ron ///Man]

I cant see why it would matter in which direction it is in. it is just letting a spec. amount of air escape past the TB. maybe your problem lies in the wiring and through moving it-- it made a contact again.

if it runs the "wrong" way, then just leave it like that.

I agree, it makes no sense... I am the type of guy who likes things to operate the way they should, so I won't be satisfied until I find the problem and fix it. I intend to ring out the harness for all connections that influence idle after I check the FPR. I'll ring connections back to the ECU connector to make sure signals are getting thru reliably. This car has only 90K miles on it and I plan to run it forever, so I want it to be 'right'...

^+1. I would leave it up side down if it works. It may be the wiring contacts. Try cleaning the contacts with some electrical cleaner.

I'll clean the contacts too. They 'looked' Ok, but could have some corrrosion I suppose.

Thanks for your help guys!!
Ron