Not boosting properly, please help!
 

Well I was cruising around in the FD yesterday and had a run with one of my friends. My car was pulling hard showing 12-10-12 and holding 12 all the way till about 110 when I shut it down. It was boosting fine until the end of the night. At WOT in 1st and 2nd I get 12psi but in 3rd at about 5,000 RPM the boost just drops to 6 for a second and then stays at 5psi. I did one last pull to see what would happen and cut it at 90 and I got only 3psi (WTF). I boost perfectly in 1st and 2nd but in 3rd after 5,000 RPM I get minimal boost.
The car has a DP and its connection with the main cat is loose. When the DP was originally put on they used only 1 gasket and some shitty sealant. We took the car to AIM in Indianapolis on the way home and they took the sealant off so now it only has 1 of 2 gaskets connecting it to the main cat, and there is a noticeable gap between the 2. So am I loosing back pressure which is resulting in my secondary turbo kicking in, or is it a vacuum hose or something. Your help will be much appreciated.

anyone?

personally, i would not suspect the exhaust. other than that, i have no idea.

if its leaking, then why is it not happening in 1st and 2nd gear? i would think the cause is something else.

anyone else want to take a stab at this?

Is your secondary turbo kicking in at all? Hard to tell in 1st and 2nd, since you "rev out" before boost transition. So under boost load in higher gears you may likely have a boost leak. Does psi ever drop to zero, or does it hover 3-5 psi at WOT?

Search "boost" and you'll see there are many threads lately. Seems like an epidemic, also. I'm a victim of 12-8-0 boost myself and waiting for parts. :(

it hovers at 3-5 psi at WOT, doesn't drop to 0.

Look under your car where the TCA arm connects to the turbo's door. The C clip might have broken off and left those 2 unattached.

Hey, I doub is your exhaust, my guess is that your Turbo Control actuator is not opening all the way; the exhaust would be insufficient to fully spin the secundary turbo plus the primary would be blowing back pressure to the secondary. check the hoses going to the TCA. Vacuum an pressure both if one is missing it will only open halfway. Also check your pressure tank an the one way valve. Good look. :) Ev7

what does WOT mean

warm operating temp

WOT is Wide Open Throttle.

Another wasted thread that no one follows through on!