Only get 7 psi of boost? Boost/Vacuum leak?
 

Hi All:

I'm trying to figure out why I'm only getting 0.5 kg/cm2 (7 psi) of boost in 3rd gear WOT.

My notable mods are:

-Power FC
-Downpipe/Midpipe/Racing Beat Exhaust
-Greddy Intakes
-Greddy Elbow
-Greddy BOV
-Custom Large SMIC
-"Rich mans" non-sequential mod
-Ported Wastegate

Power FC Settings are:

Turbo Control
1. 0.80 kg/cm2 56%
2. 0.70 kg/cm2 64%

Seq Turbo Cont "On"

I believe that I have a boost/vacuum leak somewhere in the system and I believe its mechanical vs something controlled by the Power FC. I rigged up the Fighters Garage boost leak tester and hooked it up to my air compressor and I can't seem to build up any pressure into the intake system...so I suspect that I have a leak but i'm having a difficult time tracking down the vaccum leak since I cant hear/feel the leak. Anyone have any suggestions on the best way to troubleshoot this?

check your restrictor pills PO might have removed them in order ot not blow the engine until it got a proper tune .

I don't think he's on pills, does it only happen on 3rd gear? Did it just started to happen recently? I don't recall you mention it at the BBQ.

that happened to me once... it was a vacuum hose that had come loose. i hope it is something simple like that :)

7psi is rarely ever a boost leak. If it is a noticeable leak it will usually only hit 2-3psi on the stock twins. That is common with a busted IC coupler/Hose.

7psi is almost always related to the wastegate control, the factory wastegate running off the spring pressure. I havent played with the PFC boost controller in years so cant really help you there.

Is this only happening in 3rd gear or 2nd, 3rd and 4th?

Doesn't matter which gear...WOT it can only muster 7 psi of boost.

check those pills you can feel the hoses with your fingers and if you dont feel the pills that may be your issue they are cheap and easy to replace

I'll check on the pills, thanks everyone for their input. As a followup question, can I run a manual boost controller instead if no resistor pill is present?

Yes you can run a boost controller. If the pills are there or the pic is setup to control boost and you are still getting low boost, check the lines at the front of the uim closer to the passenger side.

Ensure your second turbo is kicking in. perhaps the valve flap is stuck shut for the second turbo? Did you remove the flap between the turbo's?

Yes, you can run a manual boost controller and as long as you buy a quality one they are an upgrade over the pills.

what year is your car? 96+?

also are you getting any boost on your primary turbo or is it just your secondary your getting 7lbs?

on the 96-02's when they "simplified" the turbos they swapped the turbo control relays from individuals to a big relay package. when this baby craps out you get 0 boost on your primary and a max of 7lbs on your secondary.

Hey I'm having a similar problem I think, in every gear this happens. the boost starts dropping around 5k i believe, I dont know how to post the video on the forum but the link is down there. anyone have an idea of what that could be?

Same is happening to me... I've got a bunch of stuff to sort through though... First is replacing my cheap qaility vac lines with high quality.... One forum user said something similar, and once he replaced the vac lines, and it solved his issue, the old lines were collapsing under vacum, and and causing the trouble...

Might be worth checking into...


J.