[b16a3sol]

compression appears to be the problem then. since it seems to be spread across more than one cylinder, it has to be something they all share. head gasket is what i would think it is, but it would be weird for it to just blow up like that. also a hole developing in the block would be unheard of. i dont think they would all have their piston rings fail at the same time, unless this was a problem that took a while to notice. something might have gotten jammed in the valve train, like bits of oil filter, but that would also be strange for them all to get stuck, while lucky number 4 got nothing. i really have no idea where to go with this one, and im glad you were able to figure it out. post some more clues so that someone can hopefully stumble on the answer by the end of the week.