Low idle?

**Spikito** · 01-06-2011, 05:27 PM

Ok so I've been driving my car all day, house shopping, no issues.

parked for a couple of hours to do stuff around the apartment, then drove about 3 miles to applebees for dinner.

Cam out side, car cranked just fine, but immediately the RPMs dropped really, low, I actually thought it stalled, but it was sitting at about 300.

I give it a rev up to about 2000, falls right back down, then slowly creeps up to about 700, my norm is 900. Everytime I give to gas, and let off, it falls right back down, then creeps up a little.

It hasn't died, and otherwise drives just fine I just have to give it a little more gas before letting out on the clutch.

Once I'm in gear and rolling, it drives just fine, any bright ideas?

2000 SS, M6, 75k miles, half tank of gas, no accessories turned on, oil pressure 40 at idle, 60 under load.

**Spikito** · 01-06-2011, 08:38 PM

oh and my check engine light has been on as long as ive owned the car, bad knock sensor.....but now its off

**SajoR** · 01-06-2011, 11:06 PM

Hmmmm....I had a similar problem back in the day, but mine turned out to be a dirty MAF sensor and a shot O2 sensor. (I cleaned the MAF sensor, problem still continued, read the code it had thrown and replaced both O2 sensors. Problem went away).

It could be just a dirty MAF sensor.

That or it is strange that your check engine light for the bad knock sensor went away. I'm no expert and I could be very well wrong, but maybe your computer reset at some point, so the code isn't popping up anymore, therefore the car (computer or tune) is trying to run normal, and not compensating for the bad knock sensor and could be what's creating the problem.

Just my thoughts, but I could be way off.

**KING Z28 HAWK** · 01-07-2011, 12:42 AM

Try cleaning your MAF and TB won't hurt. Yeah its weird that the light went off. Good luck.

**Spikito** · 01-07-2011, 11:15 AM

yeah..and i mean lights go on and off....they reset after awhile, then get re-tripped, etc. but mines ALWAYS on, and it does both of these at the same time....weird

**Spikito** · 01-07-2011, 03:17 PM

ran some errands today...idled just fine.....still worries me though

**Too Fast** · 01-07-2011, 03:24 PM

This has happened to me twice with my car. For some reason, unless you have battery issues, the PCM will reset itself and it forgets how to idle and what codes were there (that's why your SES light isn't on yet). Have you had your battery/charging system checked?

A quick way to check your alternator is to turn your key on, engine off. Note where the volt meter is reading. Now, start the car. If the volt gauge comes higher, almost right away, from where it was with the key on eng. off, your alt should be fine. Otherwise, if the battery/connections check ok, somehow the PCM resets itself and it won't hurt anything.

**Spikito** · 01-07-2011, 09:53 PM

interesting....i dont have radio or clock presets to check a reset or not with....oh well, lol

**SeVeReDiStOrTiOn** · 01-09-2011, 08:19 PM

I'd pull the TB and clean the IAC valve/passage...could be all gunked just don't move the pintle. And then yea clean the whole TB while it's off

**Spikito** · 01-09-2011, 08:52 PM

IAC valve?

**Too Fast** · 01-10-2011, 02:35 AM

Originally Posted by SeVeReDiStOrTiOn

I'd pull the TB and clean the IAC valve/passage...could be all gunked just don't move the pintle. And then yea clean the whole TB while it's off

This would be for a maintenence only. His problem was somehow the PCM resent itself, then forgot how to idle, which usually takes around 5-10 miles to relearn.

Not a bad idea, tho.

**Sarge** · 01-10-2011, 03:18 AM

Yes to all the above. Also consider winter gas blend now in pumps does this also.
I noticed he said his light went out which tells me his ECM is probably learning the new winter blend gas. I know my local Shell station had summer blend up to a couple weeks ago here in South Texas.

**pajeff02** · 01-10-2011, 03:32 AM

Originally Posted by Spikito

IAC valve?

Idle Air Control Valve. On the side of the throttle body.

**Spikito** · 01-10-2011, 05:27 AM

Originally Posted by Sarge

Yes to all the above. Also consider winter gas blend now in pumps does this also.
I noticed he said his light went out which tells me his ECM is probably learning the new winter blend gas. I know my local Shell station had summer blend up to a couple weeks ago here in South Texas.

oh yeah? didnt know they did that down here....WTF is up with all this SNOW!!!, lol....its east texas, ive seen snow 3 times in 10 years, 2 of which in the last year

**az gt eater** · 01-10-2011, 05:18 PM

Originally Posted by Spikito

oh yeah? didnt know they did that down here....WTF is up with all this SNOW!!!, lol....its east texas, ive seen snow 3 times in 10 years, 2 of which in the last year

Move to a different side of texas. It's big enough. LMAO