Someone please help my brothers 00 Si sounds like a subaru wrx. The code thrown was a ignition problem or random misfire ??? I tried new plugs / wires and cap and rotor. Im thinking maybe a loss of compression in no.3 cyl because when i pulled that plug it had a slight oil looking substance on it. bad rings ? or valve guide's /seal's ???? please help !!!!!!!!!!!!!!!!!!!!!!!!!!

 

spark plug gasket under valve cover... that could be the cause and possibly the oil is blowing out the spark or won't let it conduct

 

it could also be a dirty fuel injector. i had the same problem and cleaning the injector solved it

 

I have the exact same problem, Does anyone know what the cause of this or how to fix the problem? thanks

 

does the car not run as well as before ?

 

yea, its not running as good, its having a hard time and sometimes it stalls. I just recently installed a universal high flow cat on my car. Thats the only think i did differently in the past month. you thinnk that might of made my car misfire due to a different cat? plus the cat isnt an obd2 cat but it does have a 02 censor bung but not sure if it cause it to misfire...will 02 censor have trouble reading the air flow due to a different cat?that cause it?