Failed spark plug wires and/or ignition coils can cause intermittent misfires (rough running); the Check Engine Light may also illuminate. Diagnoses of the ignition system will be necessary to determine which components are at fault.Google+
Car Problem Reports
Mercedes-Benz E320 Bad Spark Plug Wires/Ignition Coils May Cause Misfires and Possible CEL
Mercedes-Benz E320 Problem
Average Mileage: 180,058 mi (131,000 mi - 209,910 mi)
Visitor, 1996 Mercedes-Benz E320, 209,500 mi
Engine misfires. mechanic said it was a bad coil. he replaced one coil but the engine still misfires intermittently. When at the garage, the engine electronics light would not come on and the engine did not skip. The mechanic replaced a coil he thought was bad but it wasn't bad. Now, he can't get a code on which cylinder is misfiring.
Visitor, 1997 Mercedes-Benz E320, 182,000 mi
misfire and rough,plugs and coil fix.
Visitor, 2000 Mercedes-Benz E320, 131,000 mi
This is the second time in 2 months the check engine light came on. The first time they had to replace number 4 injector. Now i need to take it back again.
Visitor, 1994 Mercedes-Benz E320, 175,000 mi
I have a 1994 E320 that runs great most of the time but from time to time it will run like it's only hitting on 3 cylinders or something. Normally I can cut it off and wait about a minute and it goes back to running fine. This has been going on about a year and it's getting worse. It has 175000 miles
Visitor, 1994 Mercedes-Benz E320, 209,910 mi
Rough idle, hesitation, poor acceleration, cutting out at highway speeds. Asked dealer to diagnose. No luck on first visit. On second visit, dealer determined it was bad spark plug wires that were shorting out. All six were replaced and now runs smooth and strong.
Car runs rough and very heavy, especially when it's cold. Has a very bad engine vibration during acceleration.
Misfire on cyl 3 due to bad spark plug wire. Another time had a bad coil. Was running very rough.