# What controls the idle speed ?



## fixdaserver (Oct 19, 2003)

What controls the idle stability on a 98 540? I'm getting frequent unstable idle after dropping from highway speed to a standstill and could use some help diagnosing. Does not matter if ac is on or off. Feels like near stall then idle stablizes after 10-20 seconds. No check engine light or apparant vacuum leaks. 
Thanks for your expertise and Merry Christmas to you all! 
Steve


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## Greco (Feb 16, 2003)

The ICV (idle control valve) You might need to clean it. Its a DIY procedure you can find either on www.bmwdiy.info or www.bmwtips.com


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## fixdaserver (Oct 19, 2003)

Greco said:


> The ICV (idle control valve) You might need to clean it. Its a DIY procedure you can find either on www.bmwdiy.info or www.bmwtips.com


Bill, 
Found this good write up with pics as well. http://members.cox.net/rsm540i/ICV_Removal.htm as well. 
The ICV had black gunk on the manifold side and on the swivel thing in its' center. Cleaned it up and I'll know in a day or so if the rough idle doesn't reappear. I think this was the problem. 
Thanks a bunch. 
Steve


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## Greco (Feb 16, 2003)

Glad I can help..


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