my names Bill, I own a 2003 Pontiac Sunfire with a 2.2 Ecotec engine. I've been having some issues with it. it keeps misfiring and no one seems to know whats causing it. number one and four cylinders are getting carboned up fairly bad but two and three have normal wear a little carboned but nothing that would be causing problems. I've taken it to the dealership, all they told me was that it might be the ignition module. so these are the things that i have done , I've changed the fuel filter, the spark plugs, even the ignition module. these things only seemed to help for a short time the miss fire was still happening but not as bad.the only other things that i can think of are the coil packs, spark rail, the computer, and i doubt it but maybe the "cat". if anyone has any other ideas or knows what the problem is please let me know.

Since 1 and 4 are carboned up and 2 and 3 are not, it sounds like it could be the coil. Cylinders 1 and 4 share the same coil circuit as do cylinders 2 and 3. Of course, the 1 and 4 timing signals are also shared from the ICM, but you've already replaced that. So I would lean toward the coil as the problem. You aren't getting any codes, right?




Edited 1 time(s). Last edited Tuesday, September 05, 2006 4:46 PM

yes i am actually, the code is po300 random missfire