Boost drop problem

[localist]

Boost goes up nicely to 0.5 bar at 3000rpm but then starts to drop to 0.3 bar starting 3000rpm until 4500rpm. After that it fluctuates about between 0.4 and 0.3 bar until 6000rpm. Any idea why? Boost leak?

Engine is 4g93 gdi turbo. All stock except k&n filter, stainless steel ic pipes, bov and a mechanical boost controller that's been closed all the way (no up boost).

 

[Maxx]

maybe u close the boost controller all the way?
what type of boost controller? tulang ikan?

have u try using stock boost controller/solenoid?

 

[jinkl]

yeah do a search for boost leak test how to do it
and if its nt, then most probably ur turbine housing or exhaust side has a leak

 

[localist]

I thought if it were a boost leak, boost would go up slower than normal and maybe never reach max boost. But my case, boost goes up then down after a certain rpm. Anyway, will take the car to Skyzone this weekend.

 

[localist]

Maxx: I'm using screw type boost controller that simply leaks boost out from turbo boost source to wastegate. It's closed now so should be at stock boost.