Turbo Wont Make Propper Boost Or Hold Boost!

[chester_fb]

hey guys

ive just dont an rb25det conversion in my Hr31 skyline,

im running a Garret T3/T4 turbo

my problem is that it starts coming on boost at 4.5k rpm, makes 6psi then as soon as it hits 6psi it drops back down to 2-3 psi

it will not make over 6psi even without the actuator hose running.

the turbo is visually fine, as in no shaft play etc. we did a boost leak test and it was fine.

any ideas guys?

cheers

Chester

[TRB-001]

waste gate stuck open?

[chester_fb]

have held wastegate flapper shut with thick cable ties then taken it for a drive and no difference

[GT-RZ]

bush bearing? does the shaft spin freely. is there a problem with the oil feed?

[chester_fb]

not sure what kind of bearing it is, shaft spins freely and there is not problem with the oil feed

[mad082]

problem with the cat/exhaust? a mate had the rear honeycomb section in his cat break and it had turned sideways and was blocking the hole so that with the wastegate hose disconnected on his 3076 it was boosting up to 16psi and dropping back to 12psi at redline.

is the intake pipe being sucked shut?

is there a blockage in the intercooler piping? this wouldn't show up on a pressure test.

does it make any funny sounds?

could be an exhaust leak in the manifold

[chester_fb]

we've checked the cat, and no blockages there

no blockage in the piping, we've taken them all off and put them back on again

no funny sounds, just sounds like a normal turbo

[mad082]

what ecu? it could be an issue where the ecu is cutting back timing/fuel and it simple can't make boost.

[chester_fb]

just the stock 25 ecu, thats what i was kind of thinking, but not sure...