I have a 2009 HHR with 140,000 on the odometer. Recently, the transmission has been acting strangely. First thing in the morning, when the car is dead cold, I back it out of the garage and into the street. Everything seems ok. I put it in drive and pull away and the car shifts through all the gears. When I get to the first stop sign, about .3 of mile from home, the car doesn't seem to shift down to first. When I pull away from the stop, acceleration is very slow. I cannot feel any shifts at all. Watching the tachometer indicates no shift changes. The engine doesn't need to race to move the car, nor does it seem like the transmission is slipping. Anyway, by the time I get to the next stop light, about .7 of mile from previous stop, the car seems to be fine. It shifts through all the gears as expected.
I have had the car to my regular mechanic and he couldn't read any codes of any sort. Any idea of what to check and is it something I can do myself?

 

Sounds like the torque converter clutch is sticking, . Does the car shimmy & shake while stopped in gear?
Does the CEL come on when this is happening?
A stuck TCC should throw a P0742 or P0741 code after 2(P0741) or 3(P0742) occurrences in a drive cycle.

The TCC solenoid is PWM so, it pretty much requires a scantool to diagnose. Might be dirty ATF, bent cooling tubes, wires, TCC solenoid/valve, internal torque converter problem.
The CEL won't light up unless it happens 3 times in a drive cycle, should leave a pending code if you read before turning the engine off.

 

No, the car does not shimmy or shake when stopped and in gear. What is CEL? not familiar with that term. As mentioned earlier, no codes were read by my mechanic.

If the HHR lock-up converter behaves as the ones our company built, if the lock-up clutch is engaged when the car comes to a stop it will either 1)slip the drive clutch or 2)kill the engine. Since, at idle, the engine has so little torque, it cannot slip the clutch, thus it would kill the engine. Neither of those things is happening.

 

If you don't know what the CEL is you will be hard pressed to fix this yourself. Do yourself a favor and take it to a certified tranny guy.

 

CEL …. Check Engine Light

 

CheckEngineLight. As I said a Pending code will disappear as soon as you turn the key off. So, it needs to be read after the occurrence and before shutdown.
If it is not the TCC then what? It is PWM, meaning that the clutch varies between 0% and 100%; might be sticking partially. Possible either wrong ATF or dirty ATF. Should be Dexron VI, some shops think they are smarter than the designers.

 

Well, duh! You'd think I could figure that out. The other acronyms I got............don't know why that one slipped by.

 

It’s also referred to as a MIL Malfunction Indicator Light. Many tend to ignore it if it’s not flashing, like my niece.