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.
Average mileage: 171,719 (90,500–209,910)
22 people reported this problem
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
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.
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.