Hello everyone, just joined the forum, I have a 04 silverado 6.0 2500 hd that keeps giving me code po300 which is multipal misfire, cannot for the life of me figure out what is causing this, changed wires, plugs, cleaned injectors, question is does anyone know what would cause this, my mechanic is clueless and hate to go to the dealer, engine seems to run fine with no missfiring felt or heard, idles fine with the ocasional hickup that is probably this ethanol gas, any glues would be great, thanks.

 

your timming could be off
or your o2 sensors could be going bad my 05 car is doing the same thing ive replaced coil after coil on my number one and have deleted the code but until i change all 4 o2 sensors the car will run like crap and throw a misfire code

 

how can timing be off? it's all controled by the computer, the 02 sensors should throw a different code I thought,

 

maybe your injectors finally craped out on ya even thow they have been cleaned they stil go bad
maybe you have a bad coil