Rough Idle

[Plimbob]

My 07 has developed an uneven/rough idle and the headlights and dash lights go dimmer and brighter in cycle with the uneven idle?

Plug and wires were changed out 12 months or so ago. The dimming of the lights are throwing me off a bit?

Any thoughts?

 

[tedv]

The posting was old, so I have to assume you resolved your problem with the rough idle … that when drops is in sync with dimming lights. Years ago when most GMs used an HEI distributor, the control module would go into limp mode to get you home and the engine would run like crap. Since everything today is run by a cpu, I would suspect it's electrical supply. The obvious thing to check is the alternator output to be 14v, followed by a battery check for a shorted cell. You can go to AutoZone and they will check for a fault code for free.

If you had the problem resolved, I'd be interested in knowing what the problem was.

 

[Plimbob]

I resolved the rough idle with a MAF, throttle body cleaning and replaced a plug wire.

However, I have not been able to resolve the pulsing light problem. I have checked alternator and battery and they check out fine. I am beginning to believe it a ground problem somewhere, which is my next chore.

Thanks for posting on it.

 

[tedv]

I remember in my new design 2000 Suburban I installed a K&M air filter and kept it serviced by cleaning and oiling, but the oil would always yield from the gauze filter and deposit at the base of the throttle butterfly. It would get sticky and keep the butterfly just slightly open enough to slightly raise the idle. Had to keep cleaning the blade and base of with lacquer thinner. It was a waste of time and money putting in the K&N I think.

With the throttle bore cleaned your idle shouldn't be affected unless the throttle position sensor is malfunctioning because the computer is telling it that it is under electrical load and raising and then lowering idle. Did you have it checked for any computer trouble codes?

 

[rockenthebowtie]

On the 07 you may need to have the body control module reprogrammed with the software calibration updates there was a recall for that dont know if you ever had it done