So I have an sc400 1uz v8 with a t3 t4 turbo a 38mm wastegate 8 psi spring and hks bov... I creep from 8 psi and it fludders from 10 14 psi... I have swaped the turbo bov and wastegates 3 times and it still does it... but it works great for about a day everytime I swap the waste gate there is no cracks in the lines I have checked and checked but still cant figure it out

 

Boost controller?

 

None I never put one in yet

 

Yeah that would help

 

If the wastegate isn't letting the extra pressure out a boost controller is not going to help.
maybe your turbo is too small or your wastegate is too small.
The bov shouldn't have anything to do with it.

 

you could just have bad wastegate placement... that causes tons of creep issues.
orrrr
your wastegate is too small.
go up to a 44mm wastegate
(just get the old wastegate flanged chopped off and weld on a new one)

 

^^ Yes that is correct. going to a larger waste gate will help even if the placement is still bad. if that wont fix it then check placement or just raise the boost to where it creeps via a boost controller and run the 14 psi.

 

Well it worked on the first for about 6 mos... then blew the wastegate diaphram... got a new one with bov too and it worked great then started doing it the other day after about a year... then put the new every thing just because... worked for a day and did it again and the last 2 waste gates had no leaks and both are still good but its still doing it and when I did the tutbo I went with a 65 trim and I had a 50 trim originally... im alo just going to replace the lines today too just incase I have a leak I cant see

 

bigger turbo +low boost=bigger wastegate needed.
go up to a 44mm wastegate

 

I used to have slag from my manifold getting stuck in my wastegate and keeping it stuck open. I had to take it off and clean it out and on the 3rd time it started working fine.

Another thing is that if your turbo was originally internally gated then I know like the holsets you need to weld the internal gate port shut or else you get boost creep or fluctuations.

 

So I figured it out the vaccine lines were the wrong size... now I got out fixed its great...o and now I'm working on installing the fic8 again and got the boost controller in