Thread: ....

Originally Posted by BoostHungry

Hello im new to the forum and am looking for some much needed help. Ive used this forum many times so i thought this would be a good place to start. I am myself a mechanic and at my wits end with my GTP. its a 1998 just shy of 200k. still a very nice car ive done quite a bit to so id like to figure this out. i have no issues at cruising speed or general acceleration, starts like a new car everytime. til i get into decent boost it sputters hard like its hitting the rev limiter. about 3500rpm 6 lbs of boost or so. im running a 3.5 pulley with zzp 1.0 tune, 3" downpipe, borla catback, k&n cai, 180 thrm, al 104's, gatorback belt, poly bushings, aeroforce gauge and a few other upgrades. so far i have replaced and or checked....

new maf
iac
tps
egr
map
new plugs (tried numerous gaps)
new wires
coil packs
fuel pressure good
vacuum 20+ all new lines
new supercharger to lim gasket
pcv valve
o2's
injector o rings
seafoamed

once i get into larger amounts of boost i do get some pretty serious kr but i have a small exhaust leak so could it be false kr? what would cause so much kr anyways if its legit..? from what i can tell all my aeroforce readings look ok and the sputter isnt an actual misfire. im running out of places to look nevermind money to spend!! any advice would be greatly appriciated!

Try a different tune? Toss in a stock junkyard PCM and see what happens under boost? Try viewing live data with a scan tool and see if timing gets "all wacky"?