Misfire at 3500 RPM!
My name is Terry. I work at Rocket Chevrolet in Shelby, OH. We took in on trade a 2005 Chevy Cobalt SS Supercharged. It has a smaller pulley installed and we assume larger injectors installed and assume the ECM was reprogrammed.
When I got the car it was breaking up at idle. When you got on it, it did better but still broke up. It had a ton of codes in it. The vehicle has an Injen Air Intake and the O2 sensors were going crazy up and down. I replaced the MAF sensor (which was relocated down on the driver's side front fender area). I reprogrammed the MAF and it idles and runs great until you get to 3500 RPM then breaks up. Is there a way to program the ECM. Help!