Ok I've tried my hardest with the search button keywords are just far to common and are in 8/10 threads.

I Have a 99 FD with BNR stage III sequential turbos fuel pump has been upgraded along with injectors, Ugraded radiator and a water to air intercooler all controlled by an Apexi Power FC. Exhaust is a 3" down pipe and 3" exhaust all the way through with a resonator in place of the the Cat.

She was tuned on a dyno to 14psi but would sometimes creep to 16psi. I was out on my Sunday drive when I noticed a drop in power upon inspection of my boost gauges I have discovered it will only build to between 11 and 12psi. It does hold boost and seems to run normal aside from drop in boost and a different induction sound at WOT.

I have checked every single inch of vacuum hose. I noticed oil seeping out where the Y-pipe joins on at the front I am unsure whether it could just be seeping through the gasket or if oil would not leak if it is sealed properly.

How would a boost leak test differ to a standard single turbo boost leak test? If required I can supply photo of y-pipe join that is seeping oil if need be.

 

Make sure it isn't a boost leak on the vacuum line to your boost gauge... that one got me on my car for a couple days.

 

If the front of your y-pipe is seeping, then it isn't sealed there. Make sure you have a proper clamp, and that it is tight.

 

Picture of suspected leaking gasket

 

That is not the front of your y-pipe. Checking the gasket should be easy enough. That's not a common area for a leak.

 

That gasket seemed fine. Not sure where to look next do my symptoms suggest boost leak or something else?

 

If you are able to hold 11 psi, you probably dont have a boost leak.

 

After chasing boost leaks all weekend and not finding anything except for one at the tee for boost gauge I've only managed to bring boost up .1 of a bar. I believe I have properly tested now due to all the reading and research I have done this weekend my symptoms are now as follows;

Low boost

Boost is roughly .2 of a bar low across entire rev range.

Strange secondary induction noise

After the transition 4500rpm when the secondary begins to boost the intake noise becomes a sort of squealing noise.

I'm properly stumped as I'm not the most mechanically minded person. Anyone have some ideas?

 

Please?

 

try and see if you can find a vacume hose diagram .. I know you have the upgraded ratsnest . and just study it . ALSO try your wastegate / precontrol solenoids ..


If those solenoids are passing tomuch boost its opening up the waste gate / pre turbo sooner .

but its rare for BOTH of them to go bad at the same time .

are you getting 14 psi from the primary ? then 12 from the secondary ? ? or 12 across the board?

ARE YOU getting the same results on your PFC . does the PFC say you are only getting 12 psi ?