Hey guys, last week I was driving home from work and when I got off of the freeway and came to a red light the car started to shake and I heard a lound sound. The engine was making a sort of helicopter sound but very loud! Once I got home I just parked it and left it. The next morning my friend lent me his obdII scanner and I checked for codes because the CEL came one. It gave me code P0304 which is misfire on cylinder 4. I then went on to check the spark plug and once i pulled out the coilthe plug came out with it. They were both fried! I then got new spark plugs for all 4, and a new coil for cylender 4. I tried to put the plug in and discovered the threading was messed up. Yesterday I fixed the threading with a thread repair kit from autozone. (had to make new thread and put an insert) I then got the plug in and new coil and started the car. Still got that loud noise! turned it off, cleared codes checked again and still misfire on cylinder 4 with code P0304. Any ideas guys?

 

ok so I switched injector 3 with injector 4to see if it was the injector causing misfire, and that didn't work. I'm going to do a compression test and see whaat I get. If the compression is abnormal what doess that mean?