A couple days ago i messed with my headlights due to them not working correctly. got them fixed but ended up killing the battery twice. Now on cold starts it idles very rough and way below 1k. once ran for a while it will idle and run good. I replaced the battery thinking it was causing it and it stills occurrs. turbo timer reads 10 volt when idling rough but 14 when good. Could this be a battery problem. i still need to charge the new battery. Thanks

 

Pretty typical for the idle to be a little higher until it warms up. What Cobalt do you have and what all is done to it? What fuel? more details please.

 

it idles very low and rough like its ready to die. but fine in a couple mins. 2008 turbo tuned on 91 at 24psi. not much else

 

What's the out side temperature? Mine does the same when it's cold. It will idle low then jump up to like 900,and finally settle in around 700-800. If its really cold say below like 35, mine will idle very rough and has died, but after restart it will eventually figure things out.... I just thought it was normal, because I have heard it many time from other people. 2009 turbo, tuned on 93.

 

the outside temp has been around 40-60 everytime
edit:
started fine after sitting couple hours. not sure if its a battery issue or what