Hello my wifes 03 CTS idles really rough when in park or stopped at a light.It gets worse when you put the air on,the other day it stalled for the first time when she was taking off from a stop light.What do you think it could be?I was thinking of starting with replacing the fuel filter,the car has 56,000 I am not sure if it has ever been changed.Well, I hope someone can help me out where the problem is.Thanks

 

Have you checked the air filter to see if it is clean? If you are not getting enough air it will cause these symptoms as well.

 

SES light on, if is running as bad as you decribe it should be.Have car checked for codes,and re-post along with any mod's

 

Hello air filter is brand new and there are no lights on SES etc.Thanks

 

Codes can be stored with turning on ses light.Was anything done shortly before condition or did occur out of the blue?

 

I had the dealership upgrade my software to raise the rpm about 50 rpm. This is a known problem and was covered under my warranty.

 

hey, does it hesatate when you acclerate because it can be that you have build up on the injecters have you tried fuel injecter cleaner?

 

Try a can of Techron injector cleaner, (Pep Boys) ortry a tank of Chevron high test gas.

I use Chevron gas or shell in all my GM cars & Trucks adn Techron every 2 months.

 

Well that sounds like a very simular problem I had in my 04 CTS. But I had a check Engien light on, and the car would idle really bad in park, and also the AC effected it really bad. Well I did everything I could think of from air filter to spark plugs to fuel injector, fuel filter ect. finally I came to the conclusion that I had an electrical problem going on, But I am not familar with electonics in vehicles. So I had no other choice but to take it the the dealer. Then found the problem, They said I was haveing a problem in the ECM "Engine Control Module" they replaced it, and a wireing harness, and all is good now. Oh by the way, the Codes that came up lead to the issue of multiple cylinders missfireing, and 2 injectors not working properly, and it was all to do with a bad ECM.