Rough/Jumpy Idle at stoplights
 

Okay so I am now experiencing an issue where after driving, regardless of

how long or if engine is hot or cold, occasionally when I stop at a stop light

Gregg (my HHR) will drop in idle speed and act a bit rough, then the RPM will jump

between 500 and 800 for about 2 seconds causing the car to buck slightly,

then it will idle fine. This doesn't happen at every stop usually at least once

during my commute. The engine does not stall out or anything like that. I

did do a

search and found there were a couple people with similar issues but the

posts on those were over a year old. I read a couple different things it could

be such as a grounding issues, dirty throttle body plate, and fouled spark

plugs. I am making a new thread as our cars are approaching ten years old

and would like to know if any of you fellow HHR lovers out there have

experienced and had successfully repaired this issue over the years. I read

in the old threads that some people experienced this issue when there HHR

had as little as 13000 miles :hissyfit:

2006 HHR 2.4 2LT with almost 158,000 miles

Thank you all!:bow:

Other things: transmission OD clutch, motor/trans mounts.

There is a clutch in the auto trans. It engages for true OD, functionally disengaging the torque converter. Sometimes the mechanism goes bad.

My 5sp car would drop to a real low idle then jump up and hunt at stops at times.

I cleaned the throttle body and I have not had that happen now for about a year.

Did you just use good ol Carb/Throttle Body cleaner and a brush or something? Also is our throttle body facing upward? if so how did you stop the gunk from falling in the intake.

Use throttle body cleaner and a soft clean rag. Might be easier to just remove it, only 4 bolts.

Be sure to have the key off and disconnect the electrical connector before touching The butterfly.

Will do. I will do this hopefully later today when time permits and let ya know if it works for me! I miss my good old cable throttle body -_-

don't move the butterfly to much you could strip the plastic actuating gear

My only big concern is reading about how people experienced very high and sporadic idle speeds (sometimes up to 3000 RPM!) after doing even a simple throttle body cleaning. I guess it has to do with a relearn procedure or something? Anyone have issues with that? Any special precautions I need to take to avoid that happening? I guess it has to do with the fact that the unit is electronically controlled.

See post #5 & #7.
The book says to disconnect the battery negative cable before unplugging anything.