2000 328i rough idle when cold. Please help. - BMW Forum

shawnst · 01-12-2006, 12:01 PM

Hi, I have a 2000 328i. During winter, when I start the engine in the morning, it always has rough idle. It does not matter if I leave the car outside or in the garage over night. But after I drive it for a few minutes, rough idling will be gone. It only happens during winter. I've taken the car to the dealer, but they said nothing unusual was found. Did anyone come across same or similar problem and might know of any cure to this? Any suggestion/tips is greatly appreciated. Thanks

The car is bone stock and has about 55k miles on it.

drz · 01-12-2006, 12:32 PM

Describe the "roughness," please. Do the revs go up and down as if someone were tapping the accelerator? Does the car shake? Be a little more thorough. Most of the time, cleaning out the idel control valve solves most idling problems.

shawnst · 01-12-2006, 04:58 PM

Thanks for the reply. By "rough idle", I mean, the rpm drops (to almost 0), and then comes back up (to normal). The rpm keeps dropping and coming back up like every 5-10 seconds or so. The car does not shake, it's just the rpm not being stable. But once the engine is warmed, the problem goes away.

zibby · 01-12-2006, 05:46 PM

As "Drz" says it is most likely isv problem. Take a screwdriver or something else and lightly tap on it , if rpm stabilize you got it right !

drz · 01-12-2006, 06:11 PM

The most common fix is to clean out the ICV.

The following is a paraphrase of Bavautos' recommendation for the same problem on an e30 (I don't know how much is similar or different):

An idle that countinuously goes up and down is tipically due to eaither a lean fuel mixture or a faulty idle control system. A lean mixture can be caused by a number of things; once is a vacuum leak. Check your engine's rubber intake boot for cracks or tears, and inspect all of the air and vacuum lines. If you find no vacuum leaks, clean out the idle control valve (ICV). If that does not fix it, you may have to replace the idle control module (in the glove box, I believe).

Clogged injectors, the cold-start valve or the thermo-time switch can also cause this problem, but these are less liekly causes.

zibby · 01-12-2006, 06:43 PM

Quote:

Originally Posted by drz

The most common fix is to clean out the ICV.

The following is a paraphrase of Bavautos' recommendation for the same problem on an e30 (I don't know how much is similar or different):

An idle that countinuously goes up and down is tipically due to eaither a lean fuel mixture or a faulty idle control system. A lean mixture can be caused by a number of things; once is a vacuum leak. Check your engine's rubber intake boot for cracks or tears, and inspect all of the air and vacuum lines. If you find no vacuum leaks, clean out the idle control valve (ICV). If that does not fix it, you may have to replace the idle control module (in the glove box, I believe).

Clogged injectors, the cold-start valve or the thermo-time switch can also cause this problem, but these are less liekly causes.

What I ment by "tapping"on it is to recognize the problem ,then naturaly you have to clean it

zibby · 01-12-2006, 10:02 PM

Quote:

Originally Posted by zibby

What I ment by "tapping"on it is to recognize the problem ,then naturally you have to clean it

i
Idle control valve T-shape is part of the intake manifold system

shawnst · 01-13-2006, 06:40 AM

Thanks guys. If the ICV is the culprit, I guess the problem would happen all the time, right? The idle problem ONLY happens to me during winter. In summer months, the engine starts and idles just fine.

shawnst · 01-13-2006, 06:41 AM

Thanks guys. If the ICV is the culprit, I guess the problem would happen all the time, right? The idle problem ONLY happens to me during winter. In summer months, the engine starts and idles just fine.

used: so I am guessing it might have something to do with some sort of temperature sensor??

drz · 01-13-2006, 11:20 AM

Quote:

Originally Posted by shawnst

Thanks guys. If the ICV is the culprit, I guess the problem would happen all the time, right?

This is not true. I recommend that you go and check you ICV.

nukeduster · 01-13-2006, 11:17 PM

not true becuase the bearings inside the icv could bind during colder weather

shawnst · 01-15-2006, 08:59 AM

Ok, I got it thanks. I did a search on the forum and couldn't seem to find any ICV-DIY pages or instructions. Is it difficult to DIY?
Some people also said replacing the spark plugs solved the problem. I think I am gona try putting in new spark plugs first. I will check the ICV If I can find any ICV-DIY information.

shawnst · 01-16-2006, 04:39 PM

for those who want to replace/clean the ICV, here are some useful info:
http://forum.e46fanatics.com/showthread.php?t=245141
http://www.realoem.com/bmw/showparts...43&hg=13&fg=15

http://www.realoem.com/bmw/showparts...43&hg=13&fg=15

I managed to remove the ICV and cleaned it. But that didn't seem to solve the problem. When I looked at the ICV, there seemed to be a little gap in the ICV, is that correct? How do I check if the ICV is faulty? Also, if the ICV is not the problem, what's the 2nd most possible reason that can cause the (cold) rough idle? Thanks.

zibby · 01-16-2006, 06:14 PM

If you do not have "check the engine " light on , contact BMW dealership and let them update software on your car, it should help.