I just did some work, but first let me say when cold (at about 20 degress out) the car will idle at about 1000 rpm and may back down to 800 after it warms up. The car does not sound like its idling high (but it is higher after the work) and it does not want to pull away from me when letting off the brake. In drive it will hold about 800 rpm when stopped.

What I did was replace the two rubber pieces that meet the IAC (idle air control) valve. Or whatever Benz calls it. What I did not have was the little plastic tube that bypasses it to prevent a stall if the valve closes fully. So I used a barbed pipe that I cut to fit.

Two things may be the issue if idle is indeed high. The tube's inside diameter is too large and acting like a vacuum leak. Or I cleaned the valve and that did some damage. Looked like new inside when I was done with it.

So before I go crimping a perfectly good metal fitting to restrict flow, I would like some thoughts or info on where a healthy idle should be.

Thanks much!

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car