BlazinREDZ28

Okay everyone, It has been a while since I made the original post about this idle issue i am having. I have checked just about everything on this stupid car. Can someone please help me. Okay here is what is going on. The car runs okay at start up and then begins to get rough as it warms up. once it goes into closed loop the pcm begins pulling fuel on the left bank first. It starts pulling about 10% and gradually goes up as high as 20%. The right bank will start to pull fuel but never as much as the left bank. I have changed the left o2 sensor because it seemed to operate slower. I have changed the map sensor, installed new delco wires and plugs, had the ICM tested, changed the IAT sensor, pulled the MAF sensor and cleaned it, removed the MAF screen and cleaned the throttle plates and reinstalled the screen. I have pulled the egr valve and cleaned it, I have checked the fuel pressure and it is holding at 43.5 psi at idle with the pressure regulator vaccum referance connected and 50 psi without the vaccum line attached to the vaccum refferance. I have checked the exhaust for leaks. The only DTC that the car will set is po420, but the car has a free flow cat. The post o2 sensor switches quickly like there is not even a cat on the car. I contacted the chevrolet dealer in town and they told me they have had many complaints about this but do not know what causes this problem.WTF man they are the people who are suppose to know everything about these cars. Can someone please help me with this. I know these engines are not the most smoothest running at idle but I also own a 2005 Grand Prix with the 3800 series engine and by far it runs much smoother. Please someone help with this stupid problem. My pocket book cant handle much more. LOL thanks in advance. SETH



By the way the injector pulse width at idle is 3.4 and the engine load is 18% at idle

90rocz

I would think either coolant temp sensor or ignition module.
Pulling fuel is normal as it reaches normal temp, enrichment helps cold starts.
As the module heats up, a bad one will drop voltage and missfire, it can be easily checked @ Autozone etc.