Recently, my mini cooper experiences strange rev when driving and idling. A couple months ago, I set the lost-motion gap as per Hanes/Sprocket's advice (Thanks, man) and after that it had run pretty well, no problem at all. CTS and guage are okay showing at around mid range. It just happened a couple week ago while I was driving it, I think at that time was around 1500 rpm, and suddenly the engine was kind of revving up and down between 1300-2000 rpm resulting in shaking the car like it was hiccuping, but the engine did not stop. This happens unpredictably and I notice that sometimes it happens at around 1400-1500 rpm, but still cannot be so sure since it happens in the morning as well when it is first started, engine is still cold.
Last weekend, I cleaned the throttle linkage and stepper motor and checked all the vac pipes. Everything was fine, but the symptom was still there just happened again yesterday evening.
I suspect the stepper motor and throttle pot.
Does anybody experinece this?
Much appreciate for your help and advice.
Update:
When this happens while idling I take the air filter out and notice that the injector stops squirting, I would say just milli secs, then the rev will come down due to no fuel. The engine responds by, I think, increasing fuel pressure resulting in rich mixture going to the engine. As a result of that the rev goes up. This happens back and forth, thus, the rev will be going up and down, up and down, ..
Any ideas would be highly appreciated. Thanks a lot in advance.
Edited by Blackivory, 22 December 2009 - 09:38 AM.
