nye420

After washing the engine, very carefully. I imediately recieved a cyllinder 4 missfire code. I swaped coils with no effect, i checked the coil wiring connection which looks fine. When I originally removed the plastic cylinder head cover there was no sign of pooled water. Any help would be appreciated.

And I would like to add that this forum has been invaluable since I newly purchased my e420

Thanks

RobertG

You might have got the connector wet that goes to the coil or the spark plug wire is wet and it's grounding out.

Fabio D

Hello mate, welcome aboard! the common issue is a bad coil, maybe swap the spark too to other cyl to be sure, you would unplug (with running engine) the #4 cyl coil to be sure what is the correct cyl failing, then, stop the engine swap the cyl 4 spark+coil to the cyl 3 and see if the missfire pass to the #3cyl.. The most commong is a bad coil for sure

Fabio Daniel

e420ny

thanks I swapped coils between cylinders 1 and 4 cleared codes and the error stayed with #4 that should eliminate the coil from being the posible problem

Fabio D

Try swapping the spark plug too mate, the other sugestion is clean the fuel injector wire/connector

Fabio Daniel

e420ny

thanks
very good suggestion will let you know how i make out, i was thinking it must be the ignition side because when i unplug the #4 coil when the motor was running it didnt have any effect on the motor, but if the injector is miss firing then that could be it. i am also getting a terrible rotten egg smell

chill1

Odd timing. Just had a check engine light come on, 1999 E320' 4matic, wagon, 147,000 miles. Code came up as #4 cylinder. Replaced the coils, wires & plugs.
Not cheap, but it runs like new.

e420ny

thankyou all, turns out water had gotten onto the coil and caused my problem