Well, it's a misfire in the 4th cylinder. I know my spark plugs are due, could that be the problem? Anything else that i should worry about? Any input's appreciated.

Car: 04 WRX
Mods: vf34, sti injectors, walbro fuel pump, perrin crank pulley, borla headers, helix up and down pipes (catless), borla hush.

 

How many miles? I had a misfire code (cylinder 4? dont remember) along with 2 other codes before I had my CEL fixes. This was about ~ 35K miles. My mods are catless up, highflow TBE, IC hoses and ecutek.

A friend told me it was due to the o2 sensors reading to much fuel/too hot...?? Maybe someone can explain it better. I dont know...but now that I did the 2.2k ohm 1/2 watt resistor for the uppipe and mechanical fix for the rear o2 , none of the CEL's have come back. Im at 52K miles now.

Do you have a light flyheel?

 

i just hit 40k recently, i have the mechanicl o2 sensor fix for the dp, but nothing for the up, maybe i should do that ><

 

I would ask someone about fuel rails - I remember someone saying something about one of the cylinders being the weakest, hence, the need for fuel rails.

 

you dont need a O2 fix for the up side you will screw up your fuel mixture
running a VF34 your plugs are going to go alot quicker id replace the plugs and go from there see if it happens again.

 

i had something similar. just replaced the plugs, cleared CEL, and never came back. good luck!

 

Start with the plugs, of course one step colder than stock. Report back if the problem is still there. Check out www.clubplug.net

 

my guess is plugs also, so no lightweight flywheel then? because i think they can cause a misfire code.