Celica Forums General Discussion General MISFIRE ALL CYLINDERS

Hi friends,i have a big problem,my Celica start misfiring all cylinder, codes (P0301,P0302,P0303,P0304)same time,i tried everything and nothing,the last chance i think is ECU, a need some clue, thanks.

What did you do to the engine before this misfiring happened?


May be caused by oil or water in spark plugs' wells, or bad ignition wiring.

Hi CAPTAINSOLO, thank you, yes I put in new piston rings, same cleaned pistons, same 16 cleaned valves, new valve seals, etc. But everything was fine, I drove 3000 miles and everything was fine. Afterwards, I had a cat converter code, P0420, made by an exhaust vacuum leak, I fixed it, after that the problems begin. It is so weird, I have no idea, another very strange thing, I open the ECU BOX, and find the connecting wires with engine oil, remove the ECU, clean the connectors and the motherboard with contact wash cleaner. I know how the motor oil got there, maybe the amount of a small spoon.Thank you for your help friend.

in chronological order:

1-Engine refresh new pistons.
2-3000 miles ok.
3-code P0420 exhaust vacuum leak.Problems begin.
4-engine oil in the ECU box,maybe sucked in by ECU air intake

Check your spark plugs.

Looks like oil is getting past piston rings and foul plugs.