2009 Cobalt SS is 30 days old and 2,000 miles since new.
Under hard acceleration it sometimes runs perfect, other times will achieve about 150-200hp (according to the performance display), then have a mild asthma attack where it will cut out and lose about 25-50hp, then reengage with possibly another cutout or two.
First visit to local nearby dealer, they saw the problem on a drive, put their handheld computer on it, then ran perfect, removed computer, and it nearly died.
Back to the dealership, they said they would contact GM about any other cars with the problem. Nothing found so they say live with it until something else is discovered.
Second visit to same dealer, they claim no problem with the car, Good luck with it!
Third visit to the dealer I purchased the car from (Bill Heard Chevy, Now Bankrupt), car ran flawlessly all day. Later that night after a 90 minute sit, it started acting up again?
I've contacted GM Corporate, and they are staying in touch wth me about getting it fixed, but the telephone guy really doesn't know anything about anything.
I'd really like the car fixed, not replaced or refunded!
Any ideas how to deal with this within GM guidelines and not voiding the warranty with some sort of aftermarket tune.
I'm not smart on computer run cars, but in the old days, we'd say there's probably a fuel problem (bad fuel pump, vapor lock, etc.)
I also can't determine that it only happens under certain temperatures, humidity, cold car, hot car, etc.. It just seems to have good days and bad days and combinations of both?
Thanks for any help or ideas in advance!
jabr800

 

wow sorry to hear.

 

Sound like your misfiring ,Getting the service light flashing when this happen .
Throwing a cel if so post it and it would be easier to help.
Intermitten problem are a nightmare to diagnose.
There is a lot of possibiles for this happening
Loose connector somewhere maybe on the Pcm
Vaccum leak
Bad spark plug
Bad injector
and so on ,and so on, if you gey my drift !

 

this sort of happens to mine under light accel. Normally occurs when i shift from 1st to 2nd and then just leave it in second (because i live in a city type place) untill about 30. after 2nd it seems fine though but it does seem like its bucking slightly under light accel. very weird. after the cars is completely warmed up though, basically above 180 degrees on the gauge it seems to go away. i have an 08SS

 

MORE INFO. on the 2009 SS Cobalt

Doesn't seem to be misfiring or ignition at all. It just stops making power about 2/3rds of the way up the power band like the fuel is being intermittently being starved to the engine.
No service lights or codes at all to be found!
Any more thoughts on how to get Chevy to fix the thing instead of just staring at it when I bring it in?
I just love when Chevy says this is normal.
Someone please show me a horsepower graph that looks like the Rocky Mountains like this one, and then I'll eat my Chevy hat?
I'm getting scared some body in a Yugo might hit me from behind?
Thanks again all!


jabr800

 

Is it a complete loss in power? Because these cars obviously pull power to adjust power output to 260HP

 

also an update for my 08SS when i go to start it sometimes it does not start. It just cranks over until the computer shuts down the cranking. doesnt happen that often bu enough to **** me off. its on my list of things to get service when i have a day off and can let them keep the car for a day. I read somewhere that there is a TSB on a fuel pump problem somewhere, but i cant find it

 

Not a complete loss of power. Just has a hard time catching "its breath"!
The performance display indicates 25-50hp temporary loss, and that's about what it feels like.
Then the power trys to recover and sometimes it takes another breather or two.
By then you are at the RPM limiter, so you upshift.
Prevelant in 1st and 2nd gear. I have not wound the car all the way out in 3rd gear to find out if it will happen there too?
jabr800

 

Sounds like the car is pulling timing to adjust HP to me.

What about your A/F ratio? IS it wacky?

On some of the dynos it has been shown that the car limits a lot of HP sometimes. That's why a tune opens so much on these cars.

 

Sounds like the car is pulling timing to adjust HP to me.

What about your A/F ratio? IS it wacky?

On some of the dynos it has been shown that the car limits a lot of HP sometimes. That's why a tune opens so much on these cars.



Air Fuel Ratio does seem to be "Hunting or searching" quite often. Even when the car is on cruise control on level ground at steady speeds!
How do I get Chevy to dig around and find a problem, when these guys seem to only want to fix something if there is a "Service Engine light" or a computer code to be found?
jabr800

 

Can you get them to reflash the pcm ?
Maybe corrupted ,try unhooking the battery ,which will clear the learned setting in the pcm and see if the problem goes away for a while,
Maybe you have a flaky O2 sensor or water has goten into the connector of it and is throwing off the readings.

 

Can you get them to reflash the pcm ?
Maybe corrupted ,try unhooking the battery ,which will clear the learned setting in the pcm and see if the problem goes away for a while,
Maybe you have a flaky O2 sensor or water has goten into the connector of it and is throwing off the readings.


Good Ideas in my Opinion.
Next time (Soon) when I take it in, I'll ask them to look into this.
So far, they have done nothing because again, no computer codes or service engine light!
jabr800

 

When that happens key off then try again. Its a problem with the ECM and if you take it into a dealer and request that they contact the tech assist center about it they will hopefully get you a new ECM.

 

true, i will do that tomorrow

 

I agree with Krispy, My Best freind is a tech for GM, Talk to one of the techs if it keeps up not the service writers. They can Contact engineering at GM on these problems If Tech Assist can't help them.

 

i have this same type of prb under hard exceleration in 2nd gear..ugh..its annoying

 

With your SS/SC? or do you have a SS/TC now?

 

SS/SC i know ur talking about the T/C but my 07 has the same deal..

 

Ok, no I was jw seeing that they were talking about the TC but when you said your SC has the same problem just trying to see if it maybe a problem with the SS/TC... definitely sounds like an electric problem of some sort.... Like the wiring... or ECM...

 

idk..could be.. but woudlnt a dealer ship see that?..you know?

 

Lemon Law and get a new one.

 

Just got back from the Chevy Dealer.
They looked for the screw, felt it was too long, changed it for a shorter screw, no leaks found in the hose (They say anyhow), and sent me on my way.
This is my fourth visit for this problem, and IT STILL EXISTS!!!!
Thanks for your help but still looking for more ideas!!!
jabr800

 

When stock, I noticed under hard accel the boost would waver between 14-16 pounds, with noticable surges in acceleration. It felt like the computer was trying to limit power via timing and wastegate. Once tuned, this went away completely.

Also, the car does run rough while warming up, which is normal.

 

I've noticed this occasionally on my 09 (1200 miles on it).

 

As the originator of this thread, a note here, I've had it with the local dealer.
I sent the paperwork in yesterday to declare this thing a lemon, which I really don't want to do!
I've also sent notice to the State of Florida Attorney General!
I'd be quite pleased if the car would just be fixed to run correctly as a stock automobile, that really performs like a Sports Car should!
Maybe someone smart from General Motors will finally contact me about getting this thing to run right. Otherwise, let the fight begin!!!!

jabr800