cel light on need help

my cel has just came on for my 04 wrx giving code p0301,p0302,p0304 which is engine misfire. i have recently change out the coil, maf, air filter, spark pug, and put in injector cleaner do to the cel and it's still came back on. i was wondering if anyone of you guys know what i should do next to fix this problem?

 

do you have a lightweight flywheel?

also, can you feel the misfires?

 

have not done any clutch change on it yet so i'm not sure, and yes i can feel it sometime. I'm thinking of doing a compression test and if it goes will then I'll try swapping out injector to see if it work, I'm hopping it's not the motor please please.

 

How are your grounds? An 04 is starting to get up in age, so grounds get really crappy over time and start screwing with things. I cleaned mine up last year after it started making the knock sensor fault. A little water and baking soda did wonders to get back a rock solid ground to the car. I did the battery connections, ever neg leading from the battery to the chassis, and the knock sensor since it was as bad as the pos battery terminal.

It's just a suggestion to try out.

 

i'll give that a try to thanks

 

MY 02 WRX had misfires due to the bell mouth DP to the 3" catback.

 

i check my exhaust also and it looked pretty rusty, how do you check if it's because of the exhaust?

 

it shouldn't be related to your exhaust

 

Any updates blackstar? My car has intermittently had similar issues, so far I've only replaced the front o2 sensor, now the only code I'm throwing is P0302. Been doing massive amounts of research before I spend any more dough. I'm going to clean the MAF/grounds, and seafoam tomorrow AM before I throw anymore new parts at it.

 

His was a coil pack AND an injector

 

yup it was just one coil and one injector that went bad, thanks to nuke for your help so as fuji too

 

Mine was a bad spark plug, I replaced all four and the car is running like a dream, no more CELs either.

The job was a lot simpler than expected too.