Rough warm idle
 

Howdy,

I have a problem with my car that has me stumped. It's a 2001 986S, 105K on chassis, 35K on engine.

At warm idle, the car feels very rough. I can feel the engine shaking through the seat back. Idle fluctuation at warm idle is from 740-790 rpm, measured through the OBD2. At cold idle it is approx. 800-810, noticeably steadier.

No fault codes, no other driveability problems. No smoke.

I removed the TB and intake manifold to clean it. TB was clean, intake tubes and manifold had small oil puddles. I removed the y-pipe between the intake tube and the AOS, and plugged the intake tube opening. The idle did not improve, but there was a lot of smoke coming out of the AOS opening. Is that normal? I assumed that at idle blowby would be minimal?

Does anybody have an idea what's going on here, or what else I could check?

Thanks!!

Gary

i,m no po pro but ive read that motor mounts can mimic other problems

Good idea :) I changed the motor mount two weeks ago. It did not solve the problem though...

Remove your MAF to see if that fixes it. I've never done it myself, but from what I've heard your car will go into a special mode when it is removed. If your car is working fine again, that may be the culprit.

Thanks Viper5. I unplugged the MAF, but it didn't fix it. It set the P0102 code though, so at least I know my CEL bulb is not burnt out :)