RPMs up and down when stopped

[skibama]

Hi all. So maybe one of you can give me your thoughts on this. I've noticed lately that when I'm at a stop light, or just stopped in general, my RPMs seem to fluctuate a good bit...at least a lot more than usual. I know that sort of thing should be corrected by the computer, but has anyone had this happen?
I have an '05 V8 with 64k miles.
Throttle body? MAF sensor? I'm looking for ideas. Thanks!

 

[M1911]

Does it have a steady idle if you turn off the a/c?

 

[audiqtr]

I'd check for vac leaks (hoses, connections)
buddy had it in his car, turned out to be the Throttle pos sensor

 

[chaz]

clean ur maf sensor & throttle body & see if that helps. i see u have the volant cai, is that with the wet filter? if so, i had the same problem, so i switched to the dry powercore filter.

 

[RTAYLOR]

I've noticed lately that when I'm at a stop light, or just stopped in general, my RPMs seem to fluctuate a good bit...at least a lot more than usual.

Can you be more specific on the actual RPM fluctuations? And is it with or without the A/C on?

 

[toto]

Sounds very normal if the air conditioning is on. The computer cycles the compressor on and off surprisingly often to prevent the evaporator from getting too cold and freezing up. When that's the case, the RPM's should keep fluctuating between two levels - one where the compressor is running, and one where it's not. The tach shouldn't be moving randomly, but rather flipping back and forth between the two.

 

[Nuke]

clean ur maf sensor & throttle body & see if that helps...

That would be my first step, also.

 

[skibama]

Okay, so just fyi, I cleaned the maf sensor and throttle body and all is well. That seems to have done the trick.

 

[chaz]

cool that u updated, glad it worked out. remember tho that some people have had to clean them more often when using a "wet" filter, so id say do it every 4-5 k to play it safe.