I'm trying to fix my granddaughters 2006 HHR, when first starting cold it keeps stalling, you have to keep rpm's at about 1500 till warm, then she'll run fine all day, till engine cools off. Had a code P0102 so I replaced air filter and MAF sensor, checked for intake leaks at manifold, Put SeaFoam into gas tank and SeaFoam upper into throttle Body. Car runs fine after warm up. Is there any kind of cold start sensor?

 

hmmm

bad gas? water in lines? possible freezing? maybe lazy fuel pump or fuel filter?
hows the plugs?

 

all you mention, I would think wouldn't allow it to run as great as it does when warm, My understanding is there is no external fuel filter,but again only on initial COLD start up

 

the reason im asking about those is because you are in a snow belt area as I am across the lake from you.

Does this happen during summer months? or just in winter?

 

There is no cold start sensor as such - just the MAF sensor that monitors the temperature in order for the ECM to figure out the fuel mixture and ignition timing etc. needed.

I gather the P0102 has not returned since the MAF was replaced? And how old are the plugs that skyline26 mentioned.

I'd check the connection at the ECM, and try that battery disconnect for a few minutes (battery labotomy) to see if it resets the system as such.

 

Like I said it's my grand daughter's car, she claims she took for an oil change,and after she left check engine light came on TC turned off with light, when I checked OBDii code p0102 so I bought MAF online for $20 rather then autozone for $60, while waiting for MAF and her to bring me car. When I got car I saw Oil Guys didn't attach wire to MAF right , but I changed it and air filter anyway, erased code, check engine went out but TC stayed on, when I disconnected battery as Whopper stated that took TC light off. She hadn't told me about stalling and when I had car it was warm. Sent her on her way, next day she had new code P0171, that's when I checked for vacuum leaks, put seafoam in erased code and test drove for 1/2 hour ,ran great. it was hot again so i couldn't check for stalling. spoke to her today she said this morning it was stalling but tonight maybe 43degrees it started fine, she also said check engine is on again, I don't know code yet, won't see her or car till Friday afternoon. I'm not a mechanic, but do all my own Old School work Rebuilt a 2.8L V6 and my 371 Cid V8 with tri power for my '57 Olds , just not as familiar with newer cars

 

You can search the site for P0171, you'll find several causes. Among them are low fuel pressure and cracked flex pipe. Check for the code again on Friday and post it up here.

 

And here is a disgnostic procedure for the P0171 that looks half decent - https://www.yourmechanic.com/article...y-andrew-quinn

 

I suggest checking the EVAP purge valve (the one under the hood). They fail open which mimics a vac leak.

disconnect the electrical, diconnect tubes on both ends, blow into one end. If open throw it away.

 

Ahhh. Good one don!!!!!