Rough warm idle

[Gary Gaukler]

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

[extanker]

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

[Gary Gaukler]

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

[Viper5]

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.

[Gary Gaukler]

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