My frontier has the same issue p0300, changed coils, plugs, and i noticed cyl1 valves were wet with fuel. Has newer injectors also. With new cats. Im stumped. Runs better with cel on than when its reset to off. When its off its missing a lot. Light turns on and it runs better .
Not sure with out seeing it but sounds like an O2 sensor could be causing fuel trim problems and the cel being set could cause it to run in open loop and ignore the O2 but that's just a guess would have to see the data stream to know more hope that helps!
Please help 🙏 my Nissan 370z Nismo show P0300. I placed ignition coils, spark plugs, both pcv valves with oem parts. Clear the code but after driving around 80 miles the P0300 come back. Do you have any recommendation??
Can you feel the missfire or is it just setting the code? If the engine runs fine and you can't feel a miss it's possible that there is a crank relearn procedure. If the engine still has a random missfire there are several possibilities that you may need to look at like the catalytic converter may be restricted or a fuel delivery problem but I don't have enough information to give you a good answer.
@@rippingburnouts thank you very much for responding. The engine is running fine, only feel vibration from the engine and the engine seem very bad on gas mileage
I would look at fuel trim data to see if anything jumps out but if you are not felling the miss I would lean towards restricted exhaust like a plugged cat or a fuel delivery problem but I'm not sure without knowing what some of the sensors like o2 and maf are reading. Side note you could try some fuel injector cleaner and see if that helps dirty injectors can cause bad gas mileage and sometimes random missfires @@Qghostz
