I did short research on this, but i have this really bad problem with my cobalt, every once in a while the car will go from 1,800 rpms down to almost 200!!! lol what is going on with my car, today i was at a light it was doing at one point the car totally was shaking and the car almost shut off, i was like wow, hit the gas a little for the rpms to jump up and did it again, it cant be from sitting for a week and a half because it has happen even before i left it sitting, help guys, thanks!!

 

There is a reflash for that.
Next time it starts happening try turning the air con off see if it helps ,meaning turn the heater control to vent or floor heat only because the air con comes on on any of the defrost settings Im pretty sure.
The extra load from the air con could be causing it at idle,I think that is what the reflash might be for.

 

oo today it didnt do it, but it will most likly do it later

 

mine has done the samething, but it was when i put it in reverse.. kinda scared me, but i didnt think much of it after it stopped... maybe i should take it by the dealership...

 

im not sure what i should do, the car does it alot, and it seems like sometimes itll stall out but doesnt and just picks up the revs again.

 

My 2.2 has done this since day 1. Like if Im backing up, just giving it a lil gas and letting out on the clutch a little bit, when I push the clutch back in, it falls to about 400, and surges to almost 2k before settling back in at idle. I took it into the dealership about 3 months after I bought it, and I was told there was no problem and that it was normal operation, WTF???

 

yep i have the same thing ......usually when i put the defogerr on........
i want to know what it is..........its happend ever since i put my cold air intake on
but the thing is i dont get a CEL

 

My car also jumps around in rpms like that every once in a while. I didnt know there was a re-flash for that. I will check it out here soon though.

 

Don't know if this helps you since every cobalt has its own qwirks but my problem I had was the car would have problems idleing in traffic, if you let the clutch half out to move up with the car in friont of you and pressed it back to the floor the car would idle up to 1700 then stall out down to 500rpms then back up to 1,700 and if you give it a little gas it would level out but when it wouldnt go away after a week I took it in they said it was the fuel pressure sensor was bad.