I've got a 2006 Civic Ex 1.8l with 127,301 mi. I keep getting P303 cylinder 3 misfired detected. I've changed the plugs once and coil pack 3x's. I really don't know where to go next and hoping its not the pcm. Any ideas what it maybe?

 

welcome to the forum. check the compression in the cylinder using a pressure test. there may be leakage from the intake or exhaust valve or rings causing the P0303 code.

 

Thanks acmech52; 25970, I just did a compression check cylinders 1-3 tested at 200 psi and cylinder 4 was at 210 psi. I've also removed all fuel injectors to clean them. I swapped #1 with #3 just to see if the problem would follow. Then I cleared the code drove it for 1 hour no issues. My daughter drove it the next day and the engine light came back. I verified with my code reader and it's still there.