Help! Erratic Idle on a '90 300SE
 

Hi,
Just changed air filter, removed and cleaned the air cleaner housing. It used to idle at 700-750 rpm or so but since the new filter it is at 1100-1200 and it will idle erratically, sometimes jumping from 1100-2000 and back again in a second. I checked the vacuum lines and I did not see any off or cracked. It has been very cold 0-15 deg F but I didn't have trouble before when it was cold out. Anybody know what could be causing this? What I should look at?

Thanks,
Dan

Does anybody have info. on what could cause this?
Thanks,
Dan

Dan

It started this right after removing the air filter and the air cleaner housing? Hmmm and you double-checked all the connections?

Haasman

I know you check those vacuum lines but if I were you I'd check them again.
A sudden increase in RPM's suggests its either sucking air from somewhere its not supposed to or somthing is catching the throttle linkage.

Good luck and 'happy hunting'

Barrie

I agree, either an air leak or the linkage got jammed. on the air cleaner housing there is only one little vacuum line, that plugs into the big tube going to the valve cover. This line regulates fuel pressure a bit I think. You might check to see if it broke. Also, check the air temp sensor on the snorkel; but really, neither of these should affect the idle to this extent. I've run mine many times with the whole air cleaner lying on the bench and it idles perfectly. Check out that throttle linkage as suggested, might be a wire got on it.