03 CTS Rough Idle
 

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

RE: 03 CTS Rough Idle
 

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.

RE: 03 CTS Rough Idle
 

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

RE: 03 CTS Rough Idle
 

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

RE: 03 CTS Rough Idle
 

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

RE: 03 CTS Rough Idle
 

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.

RE: 03 CTS Rough Idle
 

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?

RE: 03 CTS Rough Idle
 

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.

RE: 03 CTS Rough Idle
 

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.