Hey everyone I'm back after a month of having a normal running Cobalt SS. New Month New problem. The check engine light went on when I boosted it above 10. The car starts getting a little wobbly until it maintains itself once it boosts above 10. After the third time of it doing that the CEL finally started blinking and is now on. I now have a P0303 or a misfire in the third cylinder, I check the spark plug (NGK Iridium ltr5ix-11) and it's basically new. The car idles just fine however and drives perfectly normal if I'm boosting under 10, and I saw this in the gauge the moment is boosted above 10 it starts misfiring until it handles itself. I am driving it passively now to avoid damage but any ideas on what this could be? Thanks!

 

I have this same issue and I have not gotten a response yet. I have tried different spark plugs, swapping the fuel pump, and the MAF sensor. Nothing has fixed this issue yet. I am going to try to swap the fuel pressure regulator and sensor to see fit hat solves the problem.

 

Yall try swapping the effected cylinders coil pack with another cylinder? If the misfire jumps to the cylinder u trade with , ur issue is a bad coil pack. That or u could have a bad injector seal. If it pops like a machine gun when it misfires, that's most likely ur issue