I have a DA with and ITR swap with a b16 cable tranny (4.40 FD), i recently got the homemade turbo kit put together and tuned to a safe but close tune with CHROME to 10 psi...
My problem from a boost leak was that the boost was falling off in higher RPMs, it would spike to 10 psi, then fall back to 6 or 5 and try to hold there....
I pressure tested the piping and found a small hole around the BOV and fixed it. After the fix there were NO leaks in the piping whatsoever...now i only get 7 psi and thats only in higher gears like 4th or 5th, the higher the rpms the more the boost drops, it falls right back to around 5...
1st 2nd and 3rd gear the boost gets a little higher but nothing above 5 psi, which i kind of understand cause there's more load in higher gears...
I've eleminated the BOV cause i tried a different one...nothing
I've eliminated the Wastegate, we completely disconnected vacuum from it and the car ran worse...
I have a boost controller hooked up...still falls off
I'm just stumped now and need more ideas...any help would be nice...

 

What kinda WG do you have... where is the vac line for the wg (off turbo housing, Intake manifold) .. also recommend checking the system for a leack. go to the HW store get PCV pipe caps ones with the squares on the top tap one for an air fitting and get a valve you can get a bike pump or air compressor and put the oter cap in the coupler sealing it off and pressurize it see if it falls off if not you knowyour leak may be from motor (internal or vac leak under boost)

 

forgot to mention i am running a t3/t4, and i'm using a turbonetics wastegate which we checked and is as good as brand new....i tested the piping by cutting off the end of an oil filter cap, putting a tire valve stem in it and clamping it to the actual end of the piping at the turbo, it holds 15 psi....no leaks...i'm starting to think my turbo is bad cause there is oil coming out of the compressor side of the turbo

 

It may be nothing more complicated than having a turbo that is out of it's efficiency range. One might think that a hybrid turbo would flow plenty for an ITR, but there might be more to the story. What is the trim of the turbo? What is your redline? Maybe the exhaust manifold doesn't flow efficiently enough to keep the T3 turbine spinning when flow demand is high.

 

got the same exact problem , has been like that for over a year now :-(. boosts fine then high revs (6K &gt it drops to 6 - 5 psi from 13ish . i have my a manual boost controller set kinda high for a stock b16a2 (13psi) it makes 225 torque in the mid range which is nice but then boost drops off where it should be making more power. gonna try an electronic controller and see what happens.

 

the turbo is a .63 a/r, my redline is 8700 rpms the turbo is a little laggy but spools around 3000 rpms ....i know the manifold is no problem cause my friend hogged it out with an excellent port job so i know it's good....i completely took the boost controller off now because it was leaking vacuum, turbo is louder spools faster, and the car runs better but still falls off...

 

 

boost cleanup in isle 5