2002 WRX Wagon Random Misfire issue!

[Kendalja]

I have a 02 WRX wagon with about 115k on it that has been getting random misfires on all cylinders. Here is a list of mods:
• VF22 Turbo
• Walbro 255 fuel pump
• Perrin short ram intake
• Grimmspeed boost controller
• Light weight flywheel
• MRT Downpipe
• MRT Cat Back Exhaust

I am still in contact with the original owner and he never had issues with random misfires, even with the light flywheel. Here is a list of things I have tried:

• Cleaned maf
• Replaced fuel filter
• New plugs x3: NGK Iridium BKR6EIX / NGK Platinum PFR6G/ NGK/Platinum PFR7G/ All gapped at .028
• Compression test @ 150 psi per cylinder
• Cleaned crank sensor
• Good fuel pressure
• No vacuum leaks
• New pcv
• Double checked all clips to coil packs
• Replaced coil packs
• Seafoamed Top End
• All grounds are good and clean
• Replaced Y pipe / All intercooler hoses and gaskets
• Cleaned battery terminals
• Fuel injector cleaner


This all started when I decided to do a tune up and replace the plugs. I have replaced the plugs three times now in the order mentioned above. As mentioned above the previous owner said he had the ACT lightweight flywheel installed for about 20k with NO issues. Car has been professionally tuned by a local shop for supporting mods. I am running out of ideas here! And yes I have read the following thread:

IF YOU HAVE A MISFIRE CODE ,PLEASE READ THIS!!!

[brittnickfriend]

My 05 wrx did that found out boost controller was bad and wasnt getting proper air to fuel also had to get the ngk iridium cool plugs cause all others missfired hope this helps to test you boost controller only if you have stock one is to unhook the hose from it and take a SHORT drive and keep psi down be sure to reset your check engine light to see if thats a fix best of luck to ya

[sxcrxy]

I have a 02 WRX wagon with about 115k on it that has been getting random misfires on all cylinders. Here is a list of mods:
• VF22 Turbo
• Walbro 255 fuel pump
• Perrin short ram intake
• Grimmspeed boost controller
• Light weight flywheel
• MRT Downpipe
• MRT Cat Back Exhaust

I am still in contact with the original owner and he never had issues with random misfires, even with the light flywheel. Here is a list of things I have tried:

• Cleaned maf
• Replaced fuel filter
• New plugs x3: NGK Iridium BKR6EIX / NGK Platinum PFR6G/ NGK/Platinum PFR7G/ All gapped at .028
• Compression test @ 150 psi per cylinder
• Cleaned crank sensor
• Good fuel pressure
• No vacuum leaks
• New pcv
• Double checked all clips to coil packs
• Replaced coil packs
• Seafoamed Top End
• All grounds are good and clean
• Replaced Y pipe / All intercooler hoses and gaskets
• Cleaned battery terminals
• Fuel injector cleaner


This all started when I decided to do a tune up and replace the plugs. I have replaced the plugs three times now in the order mentioned above. As mentioned above the previous owner said he had the ACT lightweight flywheel installed for about 20k with NO issues. Car has been professionally tuned by a local shop for supporting mods. I am running out of ideas here! And yes I have read the following thread:

IF YOU HAVE A MISFIRE CODE ,PLEASE READ THIS!!!

you must be in sydney considering that you have done work in mrt, quick qeustion were did you get the seafoam from in australia i cant find it (thats if you are form australia), and misfiring could be your flywheel if its been tuned for it its weird do you know which cylinder is misfiring? could be a ecu fault

[sxcrxy]

just realisd you said all cylinders im leaning towards the flywheel

[Kendalja]

Im actually in the states Isn't it odd that the previous owner had the flywheel installed for about 20k on it and had no misfire issues?

[sxcrxy]

Yes your right but im not saykng it os it could be could be someyhing wrong in your tune

[Kendalja]

So I replaced the Crank Position Sensor and so far no more misfires. (Fingers crossed)!! When pulling the old one it looked ok but just replaced it anyway. Is there a way to test these? Its a magnet...how can it go bad lol?