Random cylinder misfire?
I have a friend who has a Celica GTS 6spd. He has been getting the random cylinder misfire. The dealership had it and said they fixed it, something about a sparkplug being loose. Now the car has never run the same and he has taken back several times and they say nothing is wrong. Now the code came back, well at least I think it did. He erased it by pulling the ecu fuse before he had the code read. I mean he has been running like high 17's and low 18's. The spark is what gets me, couldn't a loose spark plug cause a head to crack? I've been trying to get him to get a compression check, when he gets that i'll post but untill then does anyone know what could be wrong? He says the power is there up top but not in the mid rpm's like it use to. Anything after 6k rpm in his car is quick, but before that a tercel can out run him.