ok guys i would like some input in figuring out my problem.
I have a red top sr20 and i just put in a boost controller and i tried to get 15psi. But while testing it i noticed that it would reach 15psi somtime but it then dies down to like 10 psi no matter how much i turn up the boost so im wondering if i have a problem with my wastegate ?? vaccum lines?? something…?? I checked all my clamps and they all seem fine. so i dont know what to do.
if it is a vaccum line how do i check for leaks properly?? 
I’m leaning towards your turbo is toast…
What kind of boost controller are you trying to use to control the boost ? I’ve heard that a AVC-R can be a pita the setup and if setup incorrectly it can cause that sort of problem…
i could be a few things…
- Turbo can’t keep up
- To much back pressure… ex… 15 psi with a 2" downpipe or 2 1/4 exhaust
The reason i don’t think its a leak in the lines is because if the leak is there u would never be able to 15psi or even hold 10psi
You “should” be able to hit 15psi even with a 2’’ DP and 2 1/4’’ Exhaust… it would just be a matter of when “RPM wise” as the Turbo would spool much much later…
When you hit 15, then drop to 10 and then cannot claim up anymore its normally because the Turbo cannot hold boost anymore (because its worn out) so I’d recommend removing the Vaccum line on the Wastegate (be careful of course) and see if it’ll boost past 15psi or even hold solid @ 15psi… and if not then your Turbo is indeed toast!
Few weeks ago on 240sxforums a dude was posting that he had no power and even if he removed the Vaccum Line on the Wastegate he still had no power… So I posted and told him his Turbo was fucked… (but he didnt believe me) cause he said he didnt blow oil, it didnt sound funny/bad but then a few days go by and he posts up (Yea you were right, My turbo just blew up on me)
:lol:
I think its time for a rebuild or a new turbo 
Anyone who runs 15 psi on a t25 should do more reading and learn about the setup of their motor and how it works. Do not ever run over 11-12 on a stock t25- it just makes no sense.
its not a t25 i was told it was a t28
and i have a 3" downpipe and exhaust
could my bov be the problem???
ur bov might have sumthing to do with it… when u hit 15psi ur bov is set to soft so it releases some pressure and u then drop back to 10psi…BUT in order for u to stay at 10 psi ur bov is working.
#1 turbo is gonzzzoooo.
#2 u have insane shaft play and when u get to 15psi ur turbo goes nuts and losses boost back to 10.
#3ur bov COULD be to loose.
#4 ur nuts for putting a t28 or in that fact any turbo to 15psi without changing all ur gaskets.
but there can be alot of things wrong man…try putting baby powder on ur exhaust manifold and ur turbo outlet u MAY have a tiny leak and when u hit those high pressures and high heat it expands ur turbo outlet just enough that it cant hold that little bit of back pressure u need.
could be anything man. go through the little things first.
like the previous post said take off ur waste gate actuator hose that should make ur engine think its running at full boost. if u cant hold 15psi…or even 10 for that fact then something is oviously wrong.
stock wastegates are known to not hold 15psi!
His turbo wouldnt be cooked if it can make 10psi, there is something else wrong. Could be boost leaks as well.
i bet its ur turbo to manifold gasket… and sumtimes it can get the turbo to spool and sumtimes it expands the gasket and makes it leak so it can barley spool…
just a suggestion…
but it can be a combination of like 6 different things.