Hello,

I have a 2007 Cobalt ss/sc and i love it. Alot. With the exeption that when i turn the A/C on the car idles and bogs down terribly. It nearly dies when i come to a stop. In order to get through 1st gear i have to ride the clutch to keep the rpm's up and prevent stalling.

Any advice would be greatly appreciated because i took it back to the dealer and they say they cant duplicate a problem that isn't "normal working order"

Thanks in advance,
Dave

 

join the club lol

 

X2, I was told that it may be an engine control module reprogramming issue, might solve the problem. Im getting my stage 2 kit installed in the next couple of weeks so when they flash my control unit ill let you know if that issue goes away.

 

I have the same problem, but only milder (07 s/c too). I don't get it every time I turn on the a/c, but sometimes if I turn it on at a light, the revs will go from like 600-1100 and keep bouncing back and forth. It's really weird. There's been a few times where it felt like it was going to stall. I'm out of warranty now so if someone finds a fix I'm all ears.

 

MIne just dips down once when i'm coming to a stop,but it does it everytime and it's annoying.

 

Take off tb, and clean it.

 

wat the hell does a tb have to do with ac LOL

 

trust me thats the problem i did it about 20k miles ago and it fixed it but its starting to do it again....so time to clean it again

 

Mine does that to when i come to a stop it bounces once or twice an then nothing, really annoying tried to ingnor it but cant.

 

Actually I was talking to a buddy a few weeks ago and he mentioned that too me as well. Totally forgot about it. I need to do that asap.

 

trust what he says, you'll be surprised at how gummed up the tb gets over a short period of time. and your idle stumbles/flutters because the tb butterfly is sticking.

and I recommend an oil catch can (I did the Home Depot cheapo mod) to help keep the tb clean.

 

try having the ac on at idle with tranny mounts....

 

ik the tb gets dirty. but the ac and tb have nothing to do with each other ahaha

 

the tb has the idle air control system in it which effects idle when the ac is on and i also have this issue i just blip the throttle to get the revs up before i pull out...once i am going it goes away...i am also thinking this my be a tuning concern

 

glad im not the only one with this problem i even clean the tb and that didnt help i just live with it.

 

That shoud be "you're an idiot" but who's counting

I will be a bit kinder......

When your ac cycles on, it puts more load on the engine. This causes the engine rpms to drop, and with a small 4 banger, the revs can drop enough to stall the engine. The ecm sees the revs dropping AND OPENS THE THROTTLE TO COMPENSATE.
Older cars used a simple solenoid to crack the throttle when the ac cycled on - with throttle by wire the ecm can do this directly.

If the tb is getting gummed up (and they all do eventually) the throttle may not open enough to compensate for the increased load, or it may come "unstuck" and overshoot the desired opening angle, the revs go too high, which causes the ecm to close the throttle, it gets "stuck" again and the revs drop too low and the cycle repeats itself.

Bottom line, while the ac and throttle body are not connected directly, the ac does affect what the throttle body is doing. A good cleaning should make this issue go away.

 

thanks for taking the time Buzz, you explained it well..... I didn't feel like adding any more to the argument.

 

I'm on my cell, and you can tell what I ment. Like if I said derw yuor an iodit. A simple mind can make it our lol.

 

the idle should still be a little rough with the ac on or off if the tb is dirty.

 

dumb question, whats a tb?

nvm google ftw

 

throttle body!

 

It's a 4 cylinder... its normal... either deal with the heat or deal with the bog...

 

Re-flash!

GM released a calibration update

 

Thats what I was thinking, but today i brought mine into my shop for ***** and giggles I cleaned the TB and the problem I was having has seemed to have gone away.But when I install my stage kit Ill also get the reflash.