P0303 cylinder 3 misfire code
#1
P0303 cylinder 3 misfire code
The car is a stock 2001 Z28 with an SLP lid. The car owner changed plugs to TR6 so that he could run a shot of nitrous. As soon as he completed the plug swap the car started to misfire. We swapped plugs back, got new wires, swapped coils around, pulled the valve cover and the springs and rockers looked fine. It only misfires at idle, while driving under a load there are 0 misfires in the HPTuners scanner. What could this be???