S4_Cinci (I S'edTFA)

It's there when engine is cold, but definitely gets worse at full operating temp. 2.8L 30V ATQ with Tip. Changed ECT sensor and cleaned TB valve/plate with no effect.

Inspect the bottom side during oil change and low and behold - leaking engine mount. Unmistakable purpleish/black fluid on the belly pan and dripping from the mount's lower bracket & mounting point. 110k miles with a front-end collision about 3 years ago at this point. This is the passenger side; drivers side was replaced about a year ago with exact same symptoms. This is a long way to say that you need to check these mounts out if you have a rough idle but can't seem to find any ignition related reason and the MAF and IAT sensors along with the ECT are good. Hope this helps someone out there!

audi2.7audi

Mine was the result of a blown fuse for the engine timing.

S4_Cinci (I S'edTFA)

Thanks for the input - my point here is trying to offer a solution to a frustrating problem. =)

thomas1978

up, and jump at almost 1500, then after sec. or two settle at the right spot where they should be about 1200. Later 15 - 20 sec. they go down at the 750. Strange is now with the Temp. sensor (check engine on) i start the car sometimes without problem, but rpms go right at 750 even if the car was sitting for 2 hours in 45F, and short drive of 7 miles. I just hope that when i replace the sensor everything will be fine.