What else could it be?

Question

2009 toyota matrix 1.8 L. Check engine light is on. Code is P0304 for a cylinder 4 misfire. I replaced the coil pack and spark plug. What else could it be? Also, there seems to be a sound like an exhaust leak. When placed in drive or reverse, it idles rough until take off and/or heated up to operating range. After so long it dies when stopped and in one of those two gears. Otherwise it idles fine when in park or neutral.

Answer 1

HI there

You may also have a problem with the fuel injector on cylinder #4 or some type of internal engine issue happening. You could try swapping the #4 injector with the one next to it and see if the misfire moves to that cylinder. Otherwise you may need to try a compression test to see if there is a problem internally.