UK Car Repair: jaguar x type 2.1v6, jaguar x type, trouble code

Question
hi there... am after a bit of advice... had an x type in 2.0litre v6 with a misfire...trouble code po304...missfire cylinder 4.. i removed the coil on plug and found it to be cracked and slightly melted...fitted a new set of plugs and new coils...run like a new one for a week..THEN...it came back with the same problem on the same cylinder..same fault code and another melted coil on the same cylinder..DO you think i have an ecu fault???

Answer
Hello Ashley; I just wanted to say I am thinking about your unusual problem. What colour was the tip of the plug from that cylinder? I think I would first do a compression test just to get an idea what is happening internally. It is not a typical ECU fault, the coil would appear to be overheating as opposed to NOT working