Is the spark plug wire oily at its end near where the spark is attached? If it is, the leak is external and would cause the misfiring due to sparks jumping when oil accumulates.
Did you clean the oil off?
The leak would be caused by the plug tube seal. However the leak from this area is usually not much and should take quite some time to accumulate. Cleaning up the oil with the aid os compersed air and a piece of rag attached to the end of a long screwdriver should work, at least till the oil accumulates.
Check if the spark plug wire for that particular cylinder is bad with a resistance test. There must be continuity with a resistance value of below 25 k ohms. The oil could have damaged the wire.
If oil is only on tip of spark plug, it would be internal and would cause oil burning which would emit grey smoke when engine is idling. This would foul up the plugs and cause misfiring. You did not mention any smoke so should not be this problem.
Did you retrieve the DTC?
Saturday, February 7th, 2009 AT 4:33 PM