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Need Help With Boost

eskaR

By eskaR,
in Engines & Forced Induction

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eskaR Enthusiast

eskaR

Posted
Posted

hi all i have recently got a profec b spec 2 ebc installed on my 33gtst and i was pushing 11psi with stock turbo

it was very consistent and stable it stays @ 11psi since 2k + rpm and went on all the way to redline

then the next day i realised the boost wont go over 9+ psi with the same settings (i didnt even touch the controller)

and so i tried to turn the boost controller off and it was only boosting around 5psi instead of 7psi.

i know the profec b increase boost by the % of stock boost

so i reckon the problem lies to my stock boost and thats why its only boosting 9psi with the controller

but anyone can help why issit only boosting 5psi on stock boost?

i read someone bout modding the stock solenoid, the stock boost will stays @ 5psi if the solenoid is not grounded and 7psi if its always grounded.

but it shouldnt affect me since i have an aftermarket bc already. i just thought it might somehow be related.

it was boosting 11psi all the way on the day it was set and everything was good and stable

i dunno what is causing the problem a little help will be very appreciated.

thanks

eskar

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BLSTIC Contributor

BLSTIC

Posted
Posted

Don't skylines have a two-stage system where they run 5psi at lower revs, then 7.5 at higher revs (when the factory boost controller has power fed to it)? If so, your electronic boost control has probably replaced the factory system, and you get low boost all the time until you power your (aftermarket) boost control solenoid with your new fancy profec b gadget. You'll find 5psi is the wastegate pressure.

mad082 Grand Master

mad082

Posted
Posted

this guy is spot on the money. the wastegate pressure on the r33 gts-t and r34 gt-t are 5psi and the solenoid opens at around 4500rpm to increase the boost to 7psi, so if you disconnect the controller and it goes to 5psi then there is no problem.

as for your boost decrease, do you still have the stock solenoid connected or is it disconnected? if it is connected as well as the aftermarket one then there could be an issue there. otherwise it could be one of a few things. could be a leak in the line to the boost gauge or a blockage.

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