Why only boost leak test to 15psi? You should really boost leak test to at least the pressure level you plan on running. I had a very similar problem a few weeks ago. I have a 2.3 stroker with FP 71 hta (barely bigger than stock 9 turbo) and I would spike 30 psi, and it would instantly drop to 19-20 psi. I actually got fed up and turned my boost controller all the way in, and would still only spike 30psi.. My problem was several boost leaks.

When I would begin pressurizing my intercooler piping, around 20 psi would be fine, but as I gradually turned up the pressure, at around 22-23 psi I could actually start to hear leaks. By the time I hit 35psi I could barely hear in my garage as there was air pissing out everywhere.

I pulled all my intercooler piping off, cleaned everything thoroughly, and sprayed the cheapest, stickiest 1980's hairspray I could find on all the couplers--put everything back together and BOOM, problem solved. Boost leak tested to 40psi once it was back together, and it was perfect. I backed my boost controller all the way out, then turned it in 2.5 full rotations. Went out, did a 3rd gear pull and I spiked 33psi (more than I ever hit before even with mbc maxed out) and it held 25psi at redline.

My suggestion would be to do the test again, but to a higher pressure level. If that isn't it, I would think about getting an fp 18 or 25psi wastegate actuator. Hope this helps!

 

Yeah thats what i thought, tomorrow im testing it to 25-30psi

 

Update: well I boost leak tested to 30psi and found more leaks from the J-pipe to the licp, after fixing that leak now its leaking from the compressor housing to the J-pipe and you can see it really bad on the gauge. Now onto getting the damn gasket.

 

Glad to hear you're sorting it out.

 

Yes but its a never ending story. Lets just hope thats the end of it, im also doing the tb seals.

 

Well I replaced the gasket on the J-pipe and used the hair spray method on couplers and apparently have no boost leaks according to the leak test. Now lets see what happens when the re-tuning session begins.

 

Just throwing this out there because I had a huge boost leak at my Throttle Body. My friend replaced the seals for me and my car felt brand new

http://www.streettunedmotorsports.co...body_seals.htm

Link to incase your are interested!