i've heard a lot about the icv getting carbon stuff all over it and being the culprit for idle problems... but i'm wary of doing this on mine, i was hoping someone knows of, or can tell me how to clean it.
I actually just cleaned mine, all I did was remove it and spray choke/carb cleaner into it. There really was a bunch of carbony build-up, so I just sprayed out both holes and now it works great. Just shake the extra cleaner out; it evaporates away quickly. It took my car from barely being driveable to running solid like a German tank.
I have an 89' 325i; on mine it is between the intake manifold and the boot leading to the throttle body. All you have to do is disconnect the two hoses and the electrical connection, then disconnect the rubber connector UNDER the ICV. I didn't have to unscrew anything, it just popped right off.
That's the culprit! Just pull the electrical connection off, pull the ICV out of the intake boot, and pull the little elbow out of the manifold. Once you have it all unhooked you just have to spray it out w/ some choke/carb cleaner; I made sure not to spray it way back toward the electical end. I sprayed it out really well, reinstalled it, and my car idles perfect. It really did make a huge difference, and it took all of 10 minutes.
hmmm i got it and did my best to clean it but the idle still slowly climbs to 2000 hmmm at least i figured out how to get it out and what my problem was... i couldn't see the rubber clips things underneath it, which is the first step i guess i'll reread the stuff on this i don't think its the o2 sensor it was replaced about a year ago...
edit: maybe i didn't clean it well enough... does the back half (side with conecting tubes) come off or somthing cause i can't really see that much of it just little gear type things. or maybe it was that i didn't use carb cleaner i heard i could use rubbing acohol, so i did.
alright heres an update the idle was still unstable after cleaning it so today we took it down to the shop for other things and the tech thought it was the icv also and said the the stuff behind what you can see is what was broken...so if for some guys that have tryed cleaning it out with no luck might just have to pony up the dough... that did also fix it btw old/ new pics following...