Lucid Moment

Just the other day I came back from a longer trip, turned the ac off before shutting the car off, as it was idling the rpms surged to about 1100 and remained there. Turned the ac compressor back on and idling went back to 900 rpms. Tried it the next day, same thing. No loss in boost, no cel, haven't hooked it up yet for codes.

My first though MAF sensor. Anyone have other suggestions?

"02996ttx50

may be too soon to tell. but, if it continues and the idle "hunts" from 750/800 to 1000 at idle? it is usually a symptom of a minor vac leak and/or a failing maf.

but it would be continual, not a one time occurrence.

Lucid Moment

To update this thread. I replaced the MAF sensor, and my idle has returned to normal, when not running ac compressor.

rmc1148

That MAF will get you every time lol nice to hear its running correctly.

"02996ttx50

ya, infamous mafs. haven't had one issue since replacing maf AND bmc filter. years now.

lucky fix, congrats.

wross996tt

To properly assess it was actually the MAF, plug the old one back in and see if the surging RPMs return...

Macster

My new to me (used) 2003 Turbo did something similar July 3rd 2009 when climbing the grade on 50 highway from the Sacramento area to the pass just before the road drops down to South Lake Tahoe.

Creeping along in holiday traffic in 90F temperature I noticed the engine idle speed was elevated. I check all the gages and the readings looked ok and there were no warning lights on. I believe the DME upped the idle speed to deal with possibly higher coolant temperature -- though gage did not indicate any problem but I know the gage is quite dampened.

Once I cleared the summit and began the downhill portion of the journey the idle speed returned to normal and the idle speed has not done that again in the 120K miles since. I might add the MAF is original and still in service.

While the car has been in hotter ambient temperatures it has not spent any time in a long slow procession of cars creeping their way up a mountain grade.