This is a 2008 HHR 2.2 and automatic with roughly around 236k miles. I'll try my best to describe it. So, when the car is fully up to operating temperature and you let off the gas to slow down from 55 mph to 40 mph and then go to slightly accelerate say at around 45-50 mph the go car acts like it is hunting for torque converter lockup is the way I could describe it. What I mean by that is the RPM jumps (fluctuates) probably about 200-300 rpm until you apply more throttle in conjunction with increasing speed then it stops until you let off again. The jumping can be worse around 35 mph, 40-50 mph but, after that I don't notice it.

So, let me add this to the conversation. The shift solenoid(s)? were replaced around I want to say around 100-150k miles ago by the GM (Chevrolet Dealer). I know the dealer replaced some things do to hard shifting at that time but, not sure what they replaced completely. That being said, I notice at times it can shift hard on the 2-3 shift but, at this point my thought could be a mount issue since I don't think those have been replaced. That being said, I would need to track down the paperwork to see what they replaced when they did the original work miles ago. The only other I notice is that it can shift into overdrive a little early at 40 mph. At highway speeds at can feel like there is a little slip but, watching the temperature gauge stay at 192-194 degrees at 55-60 mph I don't think so? There is no CELs on the dash at this current point. I'm just asking because I'm wondering if anyone has experienced this issue and wondering a potential cause? Perhaps the transmission is getting tired since about 95% of the miles are highway miles? But, I have to wonder about the torque converter as well? Just looking for some thoughts?

What I have tried is I did disconnect the battery for several hours and I did use Dexoit on the grounds I could get too. Anyways, just wondering if anyone else has had this issue. I hope I described it as well as I could at this point. I tried searching here and Youtube but, couldn't find what I was looking for.

 

Shift solenoids, torque converter pressure switch . Possibly the TCM need’s reflashing.

 

C.e.l.?

 

Apparently there are none.

 

Hello again. Yes no far no CELs. Now something, I just remembered from a long time ago is I thought the dealership we took it thought it might of been the torque converter but, that's been a while ago. I do now recall it did act up in the past but, we parked the car for a while. Just got it on the road and was fine for a while. Would a torque converter cause these issues? Thank you again.

 

Possibly yes, or the TCC solenoid. Low transmission fluid.

 

TLDR, try a bottle of fuel injector cleaner, and buy better fuel; see toptiergas.com. Might not help, can't hurt, good idea anyway.

I had a 2008 2.2 that did the exact same thing. It was intermittent. Never threw any codes.

I guessed it was a quirk in ECM or TCM module. Annoying but seemed harmless so I decided to live with it.

But then I wondered if it was fuel related, maybe a/f trim hunting, just not enough to throw a code. So I gave it a dose of fuel injector cleaner, and decided to buy better fuel; not premium, just major brand that do better than the bare legal minimum detergent. Can't say if it did any good or not, but I don't recall noticing the issue during the last couple years of ownership

 

Thank you for that PulpFriction. I usually get my gas from either BP or Meijer which is a top tier station and generally cheaper. That being said I thought about the TCM as well because one thing I'll add is sometimes when it is cold it doesn't seem as bad. I'll have to look at my grounds again considering this car is pretty rusty now. We've owned 17 years this upcoming fall I believe. Bought it with 20 or 21k miles and now at 236,5xx miles I believe.