usn-scpo

Went to run my errands the other morning and within the first 5 minutes of my trek, my car started running really rough, as if a coil pack had gone bad. CEL came on and was flashing, turned around and went home (about a 3 minute ride). Ran my OBD and had the code for misfire in number 3. I swapped #3 and #2 coil pack and the issue followed to number 2, easy day right, not so fast. Changed the number 2 coil pack and cleared the code. Started the car and it was idling really rough, after a couple minutes, CEL came on. Ran the OBD again and received codes for all 4 cylinders misfiring, 0300 random misfire as well as 0171 for running lean. Figured what the hell and changed the remaining coil packs and plugs. Car still idled like it wanted to stall. In frustration, I closed the hood and decided to put the car on the other side of the driveway. Started the car after closing the hood and it idled just dandy, no rough idle at all. I should say that while the idle was rough, advancing the throttle smoothed everything out. I was thinking possible ICM but am not sure of its location. Any ides/suggestions would be most appreciated. I am a schedule for a military deployment in the not so distant future and would like to get the car fixed before I deploy. Thanks and Happy New Year to all!!

A4Audi4Fun

Bad PCV might be a possible cause. With engine running, see how easily you can remove the oil cap. If it's stuck closed and really difficult to open, that's a strong indicator of a failed PCV.


My 2008 had a TSB for the PCV problem.

lloydieb8

Pcv cured erratic idle on my S3, not expensive and easy for DIY.
​​​​​​