Sometimes when I come to a stoplight the RPMs will drop by about 100 RPM and the engine feels rough for 1 or 2 seconds. It recovers and idles fine after that. It has done it both with the A/C on and off. I have noticed this off and on for a few months.

Has anybody else experienced this?

 

Not on my HHR but on my Grand Am. I had a problem in my transmission like one of the sensors went bad if I remember correctly and I just ignored it so it got worse. The car was an automatic and it got to the point where I had to shift the car into neutral or park at stoplights to keep it from stalling. That's when I decided to get it fixed.

 

I've felt that before in my HHR but never considered it a problem. It does happen but I live with it. Mine done that ever since I bought it, which will be two years at the end of Sept. I have 30000 KM on mine.

 

Mine seems to show a similar type thing, but only noticable at night when headlights are on. The lights will appear to dim for a second but there is no reflection of power loss on the RPM gauge. Also happens w/ or w/o AC.

 

Mine does this all the time when it is cold out. After it is warm it barely does it.

 

I guess that I won't worry about it then unless it gets worse or more frequent

 

I noticed it was doing it again today. This time the car was fully warmed up.

I have had the car for 7 months and 11,000 miles and I have never got above 26.8 mpg on a tank. That includes a 600 mile trip on the open Kansas Interstate. It averages about 24.5 in mixed driving (50% highway) I calculate my mpg at every fill up using a program on my computer. usually it works out slightly higher than what the DIC says. The above numbers are my calculated numbers. does this seem low for the 2.4 w auto? I am wondering if the shuddering and fuel mileage are related. I remember seeing someone say they had to have a fuel injector replaced on theirs.

Before I bought my car I rented a 06 with a 2.2 and took it to Missouri. We got almost 35 on one leg of the trip and never below 28. Judging by that it makes me wonder about my car

 

Mine has done that since new as well. I notice it mostly shortly after runnig the car at 75 on the Thruway then stopping at a traffic light a little later. I read somewhere that this is common with the ecotech motor.

 

Have you tried some seafoam, to clean the fuel system?

 

My 2.2 does this too. Not all the time, but it does it. The first time it happened to me, I thought the engine had knocked off. I guess I'm getting used to it now.




My 2.2 gets ~30mpg back and forth to work (50% highway/stop lights) and ~35mpg or better on long trips.
I wonder if this is the norm between the 2.2 and 2.4 engines.