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sc400 boosted and over boosting issues

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Old 05-16-14, 12:24 AM   #1
kolessc400
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Default sc400 boosted and over boosting issues

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
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Sc400 built for 850 rwhp 1uz...Single turbo 8 to 14 psi not sure actual hp. and tq...daily driver... 315cc injectors... AEM fic8...AEM guages...walbro 255lph...W58 swap...painted orange/ black...touch screen navigation... much more...
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Old 05-16-14, 12:33 AM   #2
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Boost controller?
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Old 05-16-14, 12:43 AM   #3
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None I never put one in yet
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Sc400 built for 850 rwhp 1uz...Single turbo 8 to 14 psi not sure actual hp. and tq...daily driver... 315cc injectors... AEM fic8...AEM guages...walbro 255lph...W58 swap...painted orange/ black...touch screen navigation... much more...
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Old 05-16-14, 02:48 AM   #4
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Yeah that would help
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Old 05-16-14, 09:44 AM   #5
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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.
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Old 05-16-14, 11:30 AM   #6
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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)
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Old 05-16-14, 12:38 PM   #7
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^^ 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.
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Old 05-17-14, 05:30 PM   #8
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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
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Old 05-21-14, 01:10 PM   #9
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bigger turbo +low boost=bigger wastegate needed.
go up to a 44mm wastegate
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Old 05-26-14, 10:14 PM   #10
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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.
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Old 06-01-14, 02:36 PM   #11
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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
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Old 06-01-14, 02:36 PM
 
 
 
 
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