VERY rough cold start - Opinions Please?

[Cloud130]

Hello! Just hoping to get a few opinions on what may be the issue here.

2007 Cobalt LT 2.2L
110,000 Miles.

Replaced spark plugs at 100,000 myself. Had mechanic replace the thermostat and temp monitor sensor, fresh coolant around the same time.

Right at the end of winter last year it began to start very rough. Start, chugs hard, RPMs stay very low, then dies. Repeats this usually two times, then starts up fine the third like nothing happened. Runs fine the rest of the day. No loss of power, no issues with acceleration, etc.

Then, next morning, super rough start again.

During the summer it never did this, then again today, it did. First cold day in a while. I replaced the battery about a month ago with a better one than it had before.

Any ideas? We use this car to commute for school, so it being down will be bad news.

Thank you

 

[YelloEye]

Changed the fuel filter? Though that's usually a consistent thing, it could cause the rough start.

Changed the air filter? Same idea as above.

When was the last oil change?

 

[onedoughboy]

Try turning the key on three or four times before cranking it over. This will help build fuel pressure.

 

[YelloEye]

Try turning the key on three or four times before cranking it over. This will help build fuel pressure.

This. If there's a fuel restriction this might narrow it down.

 

[Cloud130]

Have a fuel filter coming in tomorrow and will do the swap hopefully early next week. I will try turning the key a few times and waiting before the next cold start and see how it behaves. Thanks for the ideas, I'll check back with more info soon.

 

[onedoughboy]

I can't remember a single time a fuel filter ever solved a problem. I have pulled so many gas tanks, changed so many fuel pumps, and there always clean like new since most tanks are now plastic. And most gas stations use better filters then you'll find in and under the car.

 

[YelloEye]

Huh. I never had an issue with any of mine on the cobalts.

 

[Cloud130]

Well, winter came and went here and seemingly never showed up. Only a couple weeks was it actually very cold.

Leaving the key in the start position for a while before fully starting the car, I never had any issues, even on the cold days.

I suppose the fuel pump may be going bad after all, but for now seems to be fine if I baby it on a cold start.

Thanks again for the suggestions.

 

[YelloEye]

I recall something about supply lines going dry being related to the EVAP system not sealing.