i have a 05 sti, my mods are k&n intake, perrin modified injectors(816cc), full turboxs exhaust, walboro 255 fuel pump, turbo xs utec. the tuner i take my car to is having a hard time with the car. run like hell till it reaches5200 rpm then it misfire and totally losses power. another thing i cannot go w.o.t. bcause it do the same thing as if it hit 5200rpm. do i need a bigger turbo due to the chages in the injector size? or do you think the utec id messed up, im really getting desperate here. and if you all think i need to upgrade the turbo what recomendations do you all got for the mods that i have? or u think it the tuner?

 

Just a thought. When you put in your injectors, did you tell your ecu that they were 816 cc injectors? If you did, you might be wrong. The volume of your injectors depends on the pressure of the fuel. Increasing the pressure, increases the size of the injectors... are you following? Your Perrin injectors are rated at certain fuel pressures. *I think* that they are rated at 816 cc at 43 psi and up... I could be wrong on that. Call Perrin - they are very helpful around this stuff.

Another throught is you are getting a fuel cut because of boost creep. This is a long shot but it is very common amonge Stage 2 STIs. The stock turbo's wastegate can handle up to about 18 psi (give or take depending on the turbo and wether or not its ported). If your ECU sees boost creep, it will shut off your fuel. This would happen around 5000 rpm in 4th 5th and 6th gears at wot.

hope that helps!