I drive a 2009 HHR LT. Lately it is difficult to start when the temperature is around freezing. When it's warmer outside it starts easier with no need to touch the accelerator. I have to press the accelerator a little to get it started when cold. It starts and runs rough for a few seconds then runs fine with lots of power. I have had this happen before. I added injector cleaner to the fuel and it gradually solved the issue. I did the same now and drove the car about 30 miles on the highway to clean the injectors but the hard starting continues. What else might cause this or would I need to drive more to clean out the injectors?

 

30 miles isn’t enough to clean the fuel injectors, drive it more!
how is the air filter? How old is the air filter?
is the MAF sensor clean?
is the throttle body clean?
how many miles on the car?
if over 100,000 miles , have you changed the spark plugs? If so what brand? AC Delco 41-103 iridium?

I live in cold weather 6 to 7 months a year, don’t really have any problems cold starting. I never touch the throttle on start up.

 

Could be the EVAP purge valve (under hood) is sticky.

 

If you can blow air through it , it’s no good! Change it.

https://www.rockauto.com/en/catalog/...+solenoid,4936

 

The air filter is about 1 yr old. I have not checked the MAF or throttle body for grime but I will. The dashboard was replaced so the mileage is not accurate but it's well over 100K. I haven't changed the spark plugs. I will have a look at the EVAP too. Thanks.

 

The odometer is stored in the BCM, a code reader can retrieve it and somebody with a computer can correct the I/P.

 

To clean the MAF, only use sensor safe spray, CRC makes a good product
To clean the throttle body, use throttle body cleaner, again CRC makes a good product.
Do not use brake parts cleaner or carb cleaner, these can damage the MAF and the throttle body.
Do not touch the filament in the MAF .
Do not touch or turn the throttle plate manually, you will strip the gears inside the throttle body.
as I posted install AC Delco 41-103 Iridium plugs the engine was designed around these and there is a lot of information that other type plugs cause problems, like non start, misfires and bad fuel mileage.
Do not attempt to gap these plugs. Simply install them finger tight then torque to 15 ft lbs or tighten an 1/8 th of a turn. Use a touch of anti seize if you wish, but not too much.

 

My first guess is dirty throttle body

If it's never been cleaned then the air gap is probably tiny from the black deposits around the rim, your engine can barely breathe. When it's cold out it's possible there's a tiny amount of icy/frost collecting around the rim making the air gap even smaller - this is probably why you have to step on the accelerator (this opens the throttle plate, letting more air in) just to get it to start

I used to have a Jeep that had this same exact issue - I would need to step on the gas just to get it to start. One day it randomly turned off on me at a red light and wouldn't restart, had to get it towed to a shop. They called me back the next day with the diagnosis and it turned out it was just a dirty/sludged up throttle body

The good news is you can buy a can of throttle body cleaner for like $8-$10 and it's not too difficult to clean it, might be a good idea to clean it before it randomly turns off one day and leaves you stranded at an intersection red light like what happened to me 😅

 

I don't have a code reader. Maybe I can get an auto parts store to get the mileage. What is the I/P?

 

Yes, Being stranded is the worst. I will clean the throttle body soon. The car has been starting better so maybe the injectors are getting cleaner.