I have a 2005 Dodge neon sxt. Have a po304 code. started to change plugs and wires when I got to the 4th it had oil inside the sparkplug tube. It was lose and oil got in because of that. The valve cover gasket looks like new and no sign of oil outside of the valve cover.
I sealed up the tube, it has not leaked yet after 25 miles. It is running better but still had a miss. Could it be the coil? It was oil that caused the miss in the first place now that is fixed why is it still missing even if it misses less?
Remove the spark plugs. How does number 4 look compared to the others? If number 4 looks different, replace all four. Double check the area where the number 4 spark plug seats, as it might be damaged or full of carbon deposits due to the loose plug. It’s also possible the threads in the cylinder head got damaged due to the loose spark plug. If all that doesn’t fix the misfire, swap the coils around to determine if the misfire follows a faulty coil.
You should go ahead and replace the gasket and the plugs. The gaskets on those engines tend to leak at the rings around the plugs first before elsewhere. It is important to put RTV sealant at the corners where the cam and camshaft sensor are. You will likely find the gap on the plugs if off at this point as well.
the spark plug was never lose. the tube was lose. the plug conection is good and tight no problem there. by swaping do you mean simply turning it so if its a coil it would come up as a po301?
Swap the coil that’s currently being used on number 4 with another cylinder’s coil. If the misfire swaps to the other cylinder, you know it’s probably a faulty coil. If the misfire stays on number 4 then it is something to do with cylinder number 4, bad compression, fuel injector problem, air leak, the trigger signal from the ecm that fires the number 4 coil, etc.
No experience w/Neon here so don’t know if doing this swap is actually possible or not.
I see. It appears the coil ass’y is a single unit for all four coils. While there might be a theoretical way to hack a coil-swap experiment, the only practical way appears to be to simply replace the entire 4-coil unit.