hi all the zed developed a strange misfire today dont think i missed it when i bought the car but anyway rear cylinder passenger side bank was missing i swapped coil packs with a working cylinder and misfire was still present i then removed the plug it felt tight in places when loosening it but looked ok nice grey tip etc i then swapped it with the plug from number 2 cylinder (so rear cylinder now has coil pack and plug from number 2) and it's now ok any thoughts what it could be? originally when i found the fault removing the connector from the rear cylinder coil pack made no difference to the engine running (i 'e missfire showing up)

coil pack is faluty by the sounds of it you should be able to test this by swapping it for a known working one from another cylnder as youve done but retaing the same plug. you can do the reverse to check the plug. hope that helps

well thats the prob i did swap coil packs and the misfire stayed i then swapped plugs and the misfire dissapeared so a little strange