P0303 Code Help!! 2004 mazda3s
 

Urgg extremely frustrated!

Ok so I have a 2004 Mazda 3s (2.3l) 2 years ago my check engine light came on I went to auto zone and they told me cylinder 3 was misfiring and to change the ignition coil. Which I did and also changed the spark plugs. The light went off later that day. Now here we are cylinder 3 is misfiring again I replaced the ignition coil and spark plugs but the engine is running really rough that I won't even drive the car. I'm not leaking any fluids or have any smoke issues but the check engine light is still on and car seems to be "puttering". Im thinking fuel injector needs to be changed?! but Im not sure and really don't want to spend a small fortune trying to figure this issue out! Any help is greatly appreciated!

What kind of plugs did you put in? If you put in bosch plugs then that could be the problem as the 3 really doesn't like German spark plugs. Go with the OEM NGK's.

If you're using the NGK's then I have no idea. Try swapping the coils from one cylinder to another to see if the problem moves. Is there any oil around the spark plugs? Other regular maintenance done?