TOP 13 CAUSES OF ENGINE MISFIRE - DIY FIXES

[@abautomotive2886]

For a misfire limited to a particular cylinder (as opposed to random misfire between all cylinders): 1. Bad/worn/contaminated spark plug 2. Ignition coil failure (coil-on plug) (often a concequence of running the engine with worn spark plugs) Those two are by far the most common reasons. Much more rare: 3. Injector failure 4. Leaking/burnt valves 5. Failed valvetrain components (lifters, camshaft lobes, pushrods, valve springs, rocker arms) 6. Leaking head gaskets (actually, resulting in spark plug fouling by calcium deposits) 7. Damaged pistons, conrods or bearings 8. Manifold vacuum leaks (injector seals, although sometimes manifold gaskets too) 9. Wiring problems for injector or coil circuit (including internal PCM/control module issues) In about that order, resulted on 30 years of experience with different makes and models All other stuff mentioned here is rather a fuel mixture/fuel trim issues that might be resulting in random misfire as a consequence of too lean or too rich mixture.

[@AmbA4]

What about diluted/bad oil?

[@MechanicalSpecial]

Yeah bad engine oil may also cause engine misfire if it starts to leak into the combustion chamber.

[@anthonynicholls9415]

👍

[@maxst2]

No... thats detonation.