Well about 2 weeks ago, my freind in his type R was at a road course, mis shifted and hit 10k RPMs. So when he got home, he decided to take the head apart to see if anything got fried. Everything looked good except there was a little evidence of the valve hitting the piston in cylinder 3 (impression on the carbon) however, the valves looked fine. So we put everything back together and now cylinder number 4 is misfireing. So far we have swaped injectors, still misfiring, checked for voltage in the injectors, same thing, we do have spark. We swaped distributors with a gsr, still misfireing. Checked compression, all are good. It has us stumped. What do you guys think. Throwing the code for misfire in cylinder 4 The only thing we can think of is that we have a weak valve spring in the exhaust side and then pressure builds up in that cylinder (because the valve is not opening) then it detonates. Any other suggestions?