Originally Posted by
orbit398
Problem Solved
Figured I'd let others know what the problem was. Engine running lean and throwing the P0171 & P0174 codes due to small air leak. Only at idle would this symptoms appear. Ran great other wise. Searched and searched for leak using starter fluid on vacuum lines - found nothing. MAF sensor replacement didn't affect it. This rough engine at idle started soon after the oil change. Never put the two together.
On the oil cap is two triangles that one is to line up, I assume to indicate the cap is sufficiently tight. Well that was the issue. The triangles were lined up perfect. Problem was is the seal under the cap wasn't fulling mating with the surface (all the time) and was the source of the small air leak. The engine pulls a vacuum and was getting a little air from the oil cap. Had I tighten it like normal and not lined the triangles up, I would have never had then lean codes/engine running rough.
Local shop pressurized the engine via the intake with smoke of some sort and saw it coming out of the oil cap area. A new oil cap solved the problem. go figure.....
Assuming you actually mean the oil cap on the valve cover, this is why I never take this loose during an oil change. I doubt that the oil cap has been off over 5x since I've owned the car. Once the oil filter element is removed, I pour all the new oil back into the engine using this port. Then I re-install the oil filter element and torque that cap to the 25 N-m (18 ft-lbs) stated in the Service Manual. Never had any issues.
I gotta go look for these triangles!