Mazda3 2.0 code P0301 HELP
 

My 2008 Mazda3 with a 2.0 started misfiring got error code p0301 misfire piston 1, I changed the coil pack from cylinder 1 to 3 hoping that it will help me narrow down the issue but still have the same code, so its now the coil pack.

I'm going to change the spark plug to a different cylinder and see if that makes a difference, any other things to test or check out would be great.

Thanks

Could be a bad / plugged fuel injector too - or leaking oil or something to cause more carbon buildup in that one cylinder. It should be telling when you look at the plug, you can find some info online about running lean / rich / oil fouled by the color of the plug.
http://www.ngksparkplugs.com/tech_su...qs/faqread.asp

Thanks, I'm going to swap the injector with on another one on the rail to see if the misfire changes cylinders, ill keep this updated just in case someone has the same issue.

P0301 - misfire cylinder 1
your on the right track, coil pack switch, plug switch, other possible causes - loose connection at injector or injector (I am not sure if Mazda sets a code for injector electrical faults)

or inj. driver fault, use noid light to check injector driver

valve problem, engine problem - diagnose with compression tester
Scott

Checked Compression on cylinders and they were all really close a little over 150

switch injector from 1 and 2 to 3 and 4 and 3 and 4 to 1 and 2, now I'm getting misfire on cylinder number 2 WTF

that's a strange one... I would only have switched inj 1 with any of the others. How bad is the misfire? What is the possibility that you mixed up the injectors?

Back to the basics - repeat all steps again

Well I have it figured out.....it was...... the spark plugs:spew:
I know first this i should have checked, but they were replaced like a month before so i did not suspect it was the spark plugs, but they were. I had installed Autolite platinum and upgraded to Autolite Double platinum and that took care of it.

Hope this helps somebody in the future.