Helping a friend out

[green_GST]

My buddy has a 99 GST, very pretty car, but it's been running rough.
It caught fire a few months back in the engine bay, so he got insurance money and replaced any damaged parts. He claims it didn't run bad before the incident, but I don't remember that being the case.

The problem, if he boosts past 5 psi, it busts up horribly.
Mods:
FP evo 3 16g (ported, clipped) set for 17 psi
dejon IC piping/intake
GM maf
translator box
evo 580cc injectors
walbro 255
3" exhaust w/ stock downpipe

new NGK brp7es' @ .035" didn't help, then the evo injectors didn't help the problem, then the wally 255 didn't help the problem, new NGKs again, and it doesn't have boost leaks.

He claims it's something in the wiring from the fire, but it all looks decent and right. He put the stock maf/intercooler/piping on to see if it helped, but it didn't. I keep suggesting a AFC and wideband to tune (because he's not stock) but he insists that won't help. I imagine since the 255 is on, a afpr wouldn't hurt either.

Any tips, hints, suggestions would be appreciated!

 

[Afroclipse]

5 psi must be a typo because you really can't boost below your wastegate, tell him to get a logger, make a couple runs and see what it says.

 

[TjPhillips36]

Get a AFPR, and a logger to start. Sounds like its something fuel related.

 

[gsxtasy]

Gap the plugs down and see if that helps. Try like .028, if it still breaks up, try .024 or something, .035 is a fairly big gap.

 

[Defiant]

new NGK brp7es' @ .035" didn't help

.028"

Awcrap. First loser.

 

[green_GST]

My bad, it was really late and I was really tired, gap is .028"

He's not maxing 5 psi through the power band, the problem is when he is building boost, if it builds more than 5 psi, it will bust up and not allow it to make more. (the best way I can describe it)

 

[SpiralOut]

Boost leak.