Went to tune car and couldnt hold boost this is what all went down.Heres a quick mods
list...

Stock gsr, new t28 sized turbo (has a .48/.67a/r I know its small not
looking for big #s just a fun daily driver), 500 rc injectors,aem reg,
255 fuel pump, chipped p28 with a base map from you.

What we found was car would spike 5psi(my wga spring) @ 3200rpms but
fall off to 0 at 6500 or so if we teed the dynos boost read into intake
manifold.

However i then teed the boost read into the compressor to wga line
and held 5psi to redline...

So boost leak right, not... I have changed all clamps to tbolt
clamps, pressure tested all piping and intercooler to 25psi. No leaks.

Tried switching bovs but that didnt help.

Check valve in brake booster is good

Was gonna try a new wga but i figured if it was holding at compressor
to wga line that the wga wasnt problem. I am gonna try a new one tomorrow

Ran a compression test got 240 across the board, also ran a leakdown
test and got 5psi leakage in each cylinder which i heard was good.

I am honestly lost as i can be. I know the trubos small but i figured
it should hold 5psi. The only thing I can think of at this point is
maybe that the stock internal wga flapper is leaking. I welded it closed
but i just tacked it on the outside where the part that pivots is. But
i dont see that much exhaust excaping by. There isnt any sign of
leakage where the downpipe bolts to turbo.

Honestly i am so lost and its killing me. If you have any idea please post

 

what about at say 8 psi what happens? how massive is the intercooler?

 

I havent tried upping the boost i am gonna try tomorrow.

Its a small intercooler maybe 24x7x4

 

i cant see a 5 psi drop across that..........i can see 5 at the turbo and 3 at the manifold. up it to 8 and see from there. you may have a weak gate spring and alot of back pressure. does the car have a cat?

 

nope no cat. Its a 2 inch exit on the turbo that makes a short 90 then opens to 2.5 inch. That run to about the shifter and the rest of the exhaust is 2.25" and finished with an apexi world 2 muffler. No car or resonator. I have a electonic cutout i plan on running but not gonna install until i figure out boost issue. Just incase i give up and take it all off i can sell the cutout new..


I am gonna try to up it tomorrow and see what it falls to. Also gonna try another wga.

 

your issue screams boost leak;

hook the WG line to the charge piping near the TB, or try it off of a VAC source for a test; see what it does then.