i dont think its the coil packs. i tried one off another altezza and was still the same. it all happend on wednesday night, i was going up a steep hill in second gear betwen 4 and 5 thousand revs and just on the change over of the vvti it smoothly went off a cylinder. there was no warning lights on so i chanced driving home. next day i took the cover and coil packs off to find one of my plugs had blown out and smashed and burned all the bottom end of the coil pack. so got new plugs and went to fit them to find out the threads was gone. so when i sorted that out with a heli coil and got new plug in along with a good coil pack its knocking now and is still off a cylinder.