I have a 1999, 5.3 Chevrolet Silverado 1500, 135,000 mi. The "check engine soon light" is on and the code is P0303, #3 cylinder miss. Idles rough at about 400 rpm, seems to run fine at normal operating speeds. I checked the coil pack, changed plugs and wires, checked compression, and fuel injectors all good. Checked power to the injector to #3 and it was good. Swapped the coil pack and injector with the #5 cylinder and the code is still the same, #3 cyl miss.
Could this be a computer problem or possibly a lifter problem. I really don't want to get into the engine if I don't have to.
Dumbfounded in NJ
Monday, November 16th, 2020 AT 11:13 AM