ive searched and read about 20 posts about missfiring my problem is not related,

i have a jdm evo 8, came wth a jspeed ecu but i put a haltech e8 on it the car with the both ecu's has this wierd stuttering issue from 5600 to 7000 car pulls perfect holds 1.4 bar till 5600 then it drops about 60 hp, you cant feel or hear it stutter or missfire from inside the car only outside, inside it only feels as if it has no power above 5600. afr's at 11.8 ive changed plugs changed gaps changed coils ive changed the fuel pump the ecu ive ran it low boost high boost, richer then normal, leaner then normal nothing fixes it,

the only things i have left to change is the 2 1/4 exhaust(no cats)the injectors(doubt it all the plugs come out fine) or a boost leak, some 1 also told me it could be the optical sensor but the car runs perfect on low to mid rpms no problem at all, some i help me ive ran out of ideas, btw it stutters with the stock ecu as well with the haltech same exact problem some 1 please help me

Regan

 

Hey, I got an idea... if you want help with your evo 9, try posting in the 1-9 section instead of the X section.