P0300 random multi cylinder misfire

Discussion in 'Mechanical - Engine, Gearbox, Exhaust etc' started by chappers2000, Apr 25, 2023.

  1. chappers2000

    chappers2000 RSM Club Member

    Car has been fine but after 60 secs of enthusiastic driving, car started misfiring. Obd says P0300 random multi cylinder misfire. Had new 630 injectors and a remap in December at Engine Dynamics and I have today changed the coils and plugs. Plugs on 1 and 3 were not very tight which is why I assume there was some carbon on the base of the coils and the central electrode on cylinder 1 plug was non-existant but the two side electrodes were still there. Thought changing plugs and coils would fix the issue but still misfiring and even stalling same as before the switch.

    Not sure what the problem is now? Any ideas?

    Guess I need to take it to a garage for diagnostics/compression test so need to decide whether to use the local garage or a Renault specialist?
  2. Crankshaft position sensor dirty or starting to fail.
    Also make sure your plugs are gapped to 0.6mm
  3. chappers2000

    chappers2000 RSM Club Member

    Thanks Ian. Will check crankshaft sensor out. Plugs are gapped to 0.65 so could close them up a smidge more too.
  4. chappers2000

    chappers2000 RSM Club Member

    Will have to book it in to the garage. New plugs, coils and crankshaft sensor but no improvement.
  5. will have to do a compression test then now, i presume its not forged ?????
  6. chappers2000

    chappers2000 RSM Club Member

    No not forged…yet!
    Did notice the rubber fuel nose that I replaced to the rail as the corrugated original hose leaked, was starting to split so changed that and weirdly engine ran fine after that, but then restarted and it was misfiring again.
    Will pick up a compression tester.
    What’s the best way to disable the fuel? Fuel pump fuse? Also I assume I can just disconnect the ignition plugs to disable the ignition during compression testing?
  7. chappers2000

    chappers2000 RSM Club Member

    Got the car recovered to Engine Dynamics after it was misfiring on the drive, even at idle, with 0300 random multi cylinder misfire. Car has now been driven, on the diagnostics and even on the dyno and all the while not a thing wrong with it. No fault codes showing up or anything. Hopefully it will be ok after I pick it up.

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