[s-cars] mystery boost leak

[Mock, Bruce J (Bruce)]

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Hey all - Good day from smoky, fire-ravaged Colorado

looks like I need to come to the great well of S-Car knowledge once again...

I posted a few weeks ago that I was experiencing a whooshing sound coming f=
rom the right front of the engine bay under heavy boost but that my boost g=
auge was essentially behaving normally  -  both at idle and was still indic=
ating full boost under hard accel. as well.    Those smarter than I conclud=
ed that the gauge behavior was due to the fact that the gauge only measures=
 vacuum up-stream of where my leak (the turbo to crossover hose had a split=
 in it) was coming from.  So... I fixed the hose - and the problem was solv=
ed and the car once again ran and pulled really well.

Now - fast forward to today - I am again hearing a similar great whooshing =
sound from the RH side of the engine bay under heavy boost - coupled with a=
 lack of good hard  acceleration

Here is what I have done to troubleshoot so far:

I re-checked the hose that was leaking previously by installing our s- list=
's usual 3" drain cleanout plug boost test apparatus gizmo into the intake =
hose that normally hooks up to the MAF.  Pressurized the system to ~20psi a=
nd listened for leaks.  No leaks from the hoses but interestingly I was get=
ting a bit of leakage from - get this - the oil filler cap.  Thinking that =
this was possibly the problem, I purchased and installed a new cap.  (the n=
ew one fits MUCH more tightly than the old.!) - took the car for a spin and=
 the problem is still there:  Whooshing sound under heavy boost.  bummer.

 I can't hear the leak from the driver's seat under light (say < 12 - 14 ps=
ig) boost - but when I really put my foot into it I hear the great whooshin=
g sound and the car clearly does not pull hard the way it did before.

Obviously, something is leaking somewhere - but where?  I thought that pres=
surizing the system as described above was std. operating procedure to trou=
bleshoot boost leaks, but in this case there must be something I am missing.

Any suggestions?

Thanks Guys - This list is the best!

Bruce "leak city" Mock
bmock at avaya.com