06 Hummer 3.5 I5 RPM jumping around when Idle

[06yellowh3]

I have noticed over the past week or so that when my hummer is in idle (like when parked in a parking lot or in my garage and stopped at a red light), that the rpm gauge bounces around and when out of the vehicle I can hear the engine changing rpms. I just had my serpentine belt changed and my thermostat a couple of months ago, but other than that I haven't done anything else to the engine besides change the oil. Do you know what could be causing this problem?

 

[alrock]

Is the change in RPMs that of rising RPMs or lowering, like it is almost stalling? What range are the numbers on the gauge?

 

[06yellowh3]

the rpm's are raising...and the range is between 700 and a 1000, but there are times where it hesitates at a red light

 

[06yellowh3]

also when i have the a/c on it is almost like the motor wants to shut off if i leave it idleing to long

 

[ArtHummer]

I would start with cleaning the Throttle Body :link:

How many milled do you have on it? Maybe time for new spark plugs and coils?

 

[06yellowh3]

I just cleaned the throttle body a couple months ago and installed new spark plugs in march. and there are 127,486mi on it

 

[n8rfastback]

Clean the MAF sensor, I would check your coils too for bad connections

Sent from Nates phone...

 

[ArtHummer]

I just cleaned the throttle body a couple months ago and installed new spark plugs in march. and there are 127,486mi on it

Did you cleaned the MAF sensor?

Other reasons. bad sensor. bad plug, bad coil, water got in to the spark plugs(that happens sometime when you wash the engine)

 

[06yellowh3]

ok two of the coils look like they are corroded and how do i clean the MAF sensor, i have MAF sensor cleaner but dont know how to clean it

 

[06yellowh3]

I have not cleaned the MAF sensor

 

[ArtHummer]

ok two of the coils look like they are corroded and how do i clean the MAF sensor, i have MAF sensor cleaner but dont know how to clean it

Click on the link in post #5

 

[n8rfastback]

Just remove it with those two torx screws, add spray it out really good with maf sensor cleaner. I would try to clean up those coils somehow or just replace them.

Sent from Nates phone...

 

[06yellowh3]

Ok so i was wrong the rpm jumps are lowering rpms it jumps between 600 and 300rpms when idleing, the was one jump so bad that it killed the motor.

 

[n8rfastback]

I would suspect the coils then over the maf sensor...



Sent from Nates phone...