4-5k rpm misfire, Code P0300.

[trailshredder]

This actually started a few months ago after driving through some puddles just after a heavy rain. Would idle just fine and drive at low rpm (under 4k)just fine. If I get into the throttle it will misfire at about 4,000 - 5,000 rpms. wrote it off as a coil getting wet or something related to moisture. Now it does it even when it is dry and throws the P0300 code. This appears to be one of those somewhat generic codes that could be one of 20 things causing a random misfire! Any suggestions where to start? I replaced LIM gaskets a year ago, plugs and PCV valve at that time too.

 

[Points70]

Im havin the same problem but not all the time, just when i drive for a really long drive. They told me to check the ICM that the coils sit on top of. you can take it off and take it to any part store and they can test it for you.

 

[BlackGT97]

This actually started a few months ago after driving through some puddles just after a heavy rain. Would idle just fine and drive at low rpm (under 4k)just fine. If I get into the throttle it will misfire at about 4,000 - 5,000 rpms. wrote it off as a coil getting wet or something related to moisture. Now it does it even when it is dry and throws the P0300 code. This appears to be one of those somewhat generic codes that could be one of 20 things causing a random misfire! Any suggestions where to start? I replaced LIM gaskets a year ago, plugs and PCV valve at that time too.

start with the cheapest. i would go for plugs and wires. as for it not missfiring at idel/ low rpm...its probably there, you just cant here it.

 

[trailshredder]

Solved this today! Found out the resistance measurements for testing the coil off the car and tested each one. Ended up being my middle coil. For future reference, The primary side (bottom) is .35-1.5 ohms and the Secondary side (between the two post where plug wires go) is 5000-7000 ohms.