Transmission slips only when cold
 

So I got me a new 2008 chevy HHR 2.2L automatic in the first week of Jan 2016. Here is the deal, when I first start driving it, you have to run the rpm's up higher than normal for it to shift. It does this for the first 3 or 4 blocks, then it shifts normal. This only happens when the engine/trans is cold, such as first time I start it up at my house or when I leave from work. If I kill the engine for an hour and start it up, it is still warm and therefore shifts fine. I don't think the outside temp has anything to do with it.

I took it to a transmission shop and he drain the fluid and installed a new filter. He said that he thought the fluid may have been as much as 2 quarts low. He has no idea what could cause this until he sees an engine light, which I have not seen one yet and I have been driving it for over a month.

Sometimes it slips as soon as I put it in drive, sometimes it slips as it is attempting to shift from 1 to 2 gear. Sometimes it don't down shift, all of this only within the first few blocks of driving. Then again sometimes it drives perfect.

Before I bought the car the person I bought it from said that they had cleared the engine codes P0756 & P0700. The engine light has never came on for me.

p0700 is the TCM malfunctioning and P0756 is a bad shift solenoid. Transmission codes don't always set a CEL. You need to have a GOOD trans shop do test drive with a scanner hooked up. Or at least take it to a trans shop for an estimate.

There are 2 ways the trans fluid can disappear; a leak on the ground or it didn't get a full fill.

Give these links a read:
http://repairpal.com/OBD-II-Code-P0700
http://www.autocodes.com/p0756_chevrolet.html

Wayyyyy back when I had my auto repair shop...and specialized in automatic transmission repair and modifications I used to see a lot of the THM350's come in with that type of problem, it was always low transmission fluid. The culprit then usually was the stopper on the dip stick had slid up and gave a false reading. Now-A-Days things might be a whole lot different....I kinda miss the days when you could diagnose/repair a car without a friggin computer...

I'm thinking either you have an internal solenoid problem or you've run into some shops that don't know how to refill a trans.

Not aiming this at anyone, but some people don't realize that clearing the code does not fix the problem. If you're buying a car, and seller says they cleared codes, be very suspicious.

Hey Don, that might be a good add-on to your CEL thread.

Two things pop into my mind, loose or burnt ground connection and dirt or loose wires in the harness connection to the TCM, ok three low voltage at the battery!

If it's actually slipping, that can lead to transmission failure.
Transmission clutches and bands will wear quickly when slipping under load. Not to mention the extra internally heat buildup that occurs because of that slippage.
Best bet is to drive it as little as possible and get it to a repair shop.

http://www.obd-codes.com/p0700

Indicates communication issues with the TCM , loose wires or damaged connection harness
Loose ground wires and such


P0756 CHEVROLET 2-3 Shift Solenoid Valve Performance - No First or Second Gear | AutoCodes

Indicates no shift issues, however .....

Now as there are no current codes and the CEL is not lit, perhaps a lobotomy at the battery ground cable to reset the TCM

Disconnect the battery negative cable for at least 30 minutes

THANKS!!! You guys gave me some great info. Yes, I use the wording slipping whereas it may be just the solenoid not engaging in time .. end results sorta feel the same. No fluid leakage on the ground. Transmission shop, guy impressed me with his knowledge of the 6 speed allison transmission that he worked on for me previously. But a little disappointing with the HHR when he said he needs a CEL to begin diagnosis. Perhaps an estimate from another shop is a good idea. I am gonna try the lobotomy tonight when I get home, since that is the easiest. I'll report back with results. Thanks for all your input!!

Always do the inexpensive first ,cause they'll charge you to do the same thing!