2010 HHR No codes. engine idles rough going up and down only in Park or neutral once it gets warmed up. Once its warm above 170 it acts up. Drives fine and idles ok though.
Cold its fine and idles. New throttle body in April. Anyone had this issue?

 

Welcome to the site, have you cleaned the MAF sensor? How many miles on it?

 

When the engine is cold, it's running a "canned" program that operates in open loop. In other words, there is no feedback to the computer that adjusts engine parameters.

Once it warms up, the computer now controls the engine based on feedback from sensors. The computer is likely getting bad info from a sensor.

Is there a check engine light? If not, you may have to look at sensor output in real time using a scanner and look for erratic data.

Steve

 

When it's warmed up and not right unplug the MAF. Does it run better? Yes means bad sensor. Tap the sensor with engine idling. Does it skip? Yes, bad sensor.

 

I'd start simple. Clean the MAF sensor, clean the throttle body, toss a bottle of injector cleaner in the fuel tank.

 

Is this the reason you replaced the TB?
When did it start?

 

It ended up being the MAF sensor and I had a cracked PCV hose coming from the valve cover. I unplugged the MAF sensor and it ran fine. I had replaced it in August and it ' s a GM part. Anyways all set! Thanks for the input, sorry I didn't respond quicker!

 

Thank you for sharing your experience and resolution of the issue with your HHR

 

There are 2 codes associated with a bad MAF. 1 for the temp sensor and 1 for the air flow sensor. If it was bad or unplugged some codes should have set.