Toward the end of a 100 mile trip the engine in our 1995 E320 began running rough when the car was stopped. Pulled the spark plugs and the plug in Cylinder 1 was wet and the top of the piston looked wet also. The rest of the spark plugs appeared normal and the top of the those pistons were dry. Replaced the spark plugs and the problem still exists. It seems like the ignition wire to Cylinder 1 has gone bad and the spark plug is not firing. In the past I've had one of the 3 coil packs suddenly go bad, but in this case the engine does not run as rough as with one bad coil pack. What's the likelihood of the ignition wire that runs from the coil pack atop Cylinder 6 to Cylinder 1 suddenly going bad while driving? Any other ideas as to the cause of this problem?

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Fred Hoelzle

If you have an OHM meter measure the resistance, & remember resistance is futile.

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

i believe that the resistance of each of the wires and under coil connectors should not exceed 2k ohms. with suspect wire connected to a DVM, wiggle/ bend the wire, if the reading fluctuates and exceeds 2kohms, its probably a bad wire.

another thing you can try , is to move the wire . the 1&6 wire and the2&5 wires can be interchanged. if your missfire moves with the wire, you've found your problem .

good luck