1995 C220 no spark on 1 and 4 cylinders

[wiskas69]

Have no spark on number 1 and 4 cylinders on a 1995 C220. Have fitted a brand new engine wiring loom, still the same. Have removed both ignition coils and had them tested. Both tested ok. What triggers the coils? Is it the main ECU or is there another module just for the ignition system? Or am I completely on the wrong track? Any help appreciated.

[n0alpha]

Have you tried replacing the wires that go from the coils to the spark plugs?

Also, now is a good time to replace your spark plugs.

[livegood]

I'm having troubles remembering now, does cyl 1 and 4 share a coil? or is it 1&3, 2&4? Anyways, if they share the same coil, then swap the coil with the other one and see if the misfire switches cylinders. Otherwise the next step I'd check is the plug wires, these fail pretty common too. And like always, whenever you are dealing with misfires, its a good time to change the spark plugs.

[RonCT]

Hi Guys,

On my C240 V6, there is a slight intermittent misfire on the No. 4 cylinder. The coils have been interchanged and the spark plugs changed and still the same misfire on the same cylinder persists.

The workshop have had the car for 2 weeks and I have heard today that they have opened the wiring loom and are trying to trace a "breakage" in the wires.

Auto-electrics are not my strong-point. Can anyone please advise me if the what they are doing to my car. is: opening the wiring loom is a good idea?

Thanks in Advance

[livegood]

any updates on what you found?