c280 rough idle
 

My 94's C280 mileage 137k km idling rough after engine wash. What could be the problem?

You got water somewhere that it ain't supposed to be. If you drive it enough it MAY dry out and go back to giving you a smooth idle. You have to be real careful when washing these newer cars.

Check the ignition wires. Late in the evening, when it's dark, fire up the car ad open the hood. Mist some water on the wires while it's idling. If you see ANY sparks or arcing, then it's time to either replace the wires or the end connectors.

104 engines have cavities in the head for the plugs and no way for the water to get out..The valve cover must be covered when washing engine.
The best way to dry them out is to remove the plug/wire cover and blow the cavities out with air ..
If it still skips after drying, replace the 3 plug boot/connectors under the 3 coils ... they are infamous failure part and short $$$.

There also have been coil and injector harness failures with the 104 engines as well, water sems to aggrivate it.



Joe