I will try to make this simple...
Car is 2003 WRX Wagon. When purchased it was stock, except SPT cat-back (76K on it) threw a P0302 code the day I bought it. Battery and #2 plug replaced by dealer because it was fouled. I was told car had the 60K service done by PO.
1 year later (90K on car):
Car has UP, Bosal shorty divorced wastegate DP, SPT cat-back, stock main cat. No other mods.
Car was Dyno tuned by Dynoflash about 8 months ago (didn't have UP on at the time). Put down around 200 / 200 conservatively. I was running out of fuel up top. He backed boost down, and made it nice and safe. He had to put my car on the charger because he said my voltage was low...during tuning (and this was a 2 month old Subaru battery!)
I replaced the fuel filter a few months after my dyno tune, and found I made more boost (max 17 psi in 3rd gear WOT) afterwards. I am guessing the FF was partially clogged.
I replaced the stock UP with a generic catless UP a few months later. Car ran great. I didn't get it retuned either........
Yesterday, I got another check engine light..and it was found to be P0302 again by the dealer, another fouled #2 plug! They say it is because I am tuned, and my a/fs are out of range rich. Even though I fouled the same plug bone stock!
The plug was visably black with soot. Def. running RICH.
What say you gurus? Do I need retuned? Do I need a step hotter plugs? Do I need a new battery? Do I need to flog my car more?
CN: Fouled #2 plug...second time! What gives?