Boost Problem, Cant Diagnose.

[BuNcHeSs]

Ive searched multiple threads and I could never find someone with a similar problem as mine.

I have a 1997 GST automatic and one day when I went out so start it up it it cranked abnormally slow and then started. I drove down the road and turned to get on the highway and I literally have literally no power under boost and the turbo seems to be spooling. The other thing is my gas mileage severly dropped. I went from about 22 mpg to around 10.... And im throwing no codes... Ill list everything ive done..

New NGK plugs capped to 31
New Wires
Compression tested all in 150s
Stock blow off valve broke, bought an adapter and got a knock off greddy
Boost leak tested and fixed every leak i found
New IAC
New MAF
New fuel filter
I removed the BCS restrictor
High flow intake with the chrome down pipe..
and i cleaned out my intercooler this summer

The car runs absolutely fine until I hit boost. I have sort of a high idle. around 2k but its always been there since I got the car.
Thanks for any help..

 

[Bud92gsx]

Plug gap Should be .028

700-900 should be the idle.

Boost leak..A large one.Like an ic pipe popped off is how i perceave your issue.

 

[BuNcHeSs]

Plug gap Should be .028

700-900 should be the idle.

Boost leak..A large one.Like an ic pipe popped off is how i perceave your issue.

There isnt any large boost leak.. its been pressure tested and smoke tested. I read my aftermarket boost gauge and it builds up to about 5 pounds off boost and will hold it steady if i dont accelerate anymore and as soon as i do the turbo cuts out and goes straight into vacuum

 

[Bud92gsx]

Pressure tested to what psi?

If your are running 12 psi.Its always a good idea to test @ 5 over, or even @ 20 psi To be safe.

 

[staytrue2007]

Have you smoke tested the intake side after the throttle body? Check the intake gasket and throttle body gaskets. Also check your vacuum hoses and pcv valve.

 

[diamondboy]

Start with the simple things battery fuses
and negative battery cable.
Check all connections on plugs for harness and fuse box.
Check all your grounds .
Check your ecu for sure .

Make sure all connections on battery are tight and clean.
Also check ground wires for corossion.

 

[Thenewguy90]

I was wondering if anyone could possible shed some light on an issue I'm having with my 1g talon