So my car which is a 2002 wrx with the ej20 motor has recently started misfiring , it idles at like 1300 rpm and is misfiring on cylinder 1 and 3 giving off codes only p0301 and p0303 on the obd2 scanner. Anyone have this problem or think they know the cause? I'm leaning towards a bad fuel rail because both cylinders are fed fuel off the same rail , does that seem like a cause? Still gunna pull the plugs and check em eventhough they have less than a thousand miles on em . Please respond with any info , I miss driving my subie life ain't the same driving auto now : /

 

Check all ur vacuum lines ...first and replace ur plugs

 

If not check your coilpack also

 

ya id suggest checking coil packs and your plugs... easiest way to see if you have a bad coil pack is taking off one of the good ones (cylinder 2,4) and switching them with the other ones... also do you have any mods? like possibly a lightened flywheel? because that could cause a misfire code as well. either way good luck man!