Registered Forum User
500SD
Posts: 719
Join Date: Feb 2005
Location: South East
Mood: Out with the grey....in with the satin black
Probably down to a faulty/ dirty/ wet coil. Identify which cylinder isn't firing, remove coil, clean it up & clear any moisture near the plug. Refit coil & test. If you're still having problems, remove & clean plug too.
It is quite common. Do a search on 'coil' in the 749/999 board.