300SE (W126) Misfiring

[Rob Pruijt]

When I start my car in the morning it runs fine for 5 minutes and then starts misfiring.
This stops when I turn the engine off for about 15 minutes, the rest of the day it runs fine. The problem is not fuel related, it does the same on Petrol and GPL.
The distributor cap, rotor and cables are not that old and look good.
Yesterday I resealed the top front engine cover and replaced the camshaft seal. This seems to have stopped a minor oil leak but it still misfires.

[wbain5280]

Try this, look for arching in the engine compartment while it's running, at night. Take the distributor cover off as well as the coil cover. Check all the spark plug wires for arching.

My coil wire is damaged where it clips on to the distributor base under the cover. I slathered on some MB sealant, the same used to seal the front cover.

[Rob Pruijt]

Today changed the relatively new Beru cap, rotor and wires for original Bosch and put new plugs in. No more stalling and misfires. The Bosch wires are thicker and less flexible than the Beru wires.