Chattering boost under heavy load?

[Jim Green]

While I'm wasting time at work, I might as well ask
for some theories.  I have the car set at 22psi of
boost using a 1.8 bar spring, slightly cranked down
adjustable wasegate, and a pressure regulator adding
boost pressure to the top WG chamber.

I gears 4 and 5 especially when going up hills at WOT,
the boost will sometimes start to chatter, and make
the car buck.  I shimmed up my Forge BPV and it helped
for lighter loads.

Could the WG chattering really make boost surge like
that?  I think it wouldn't be more progressive, which
makes me look at the BPV again. It is sharing a few
vacuum lines with stuff like the FPR and diff lock
which could screw it up I guess.  Any thoughts?

Thanks

=====
Jim Green
'89 90tq 034EFI, Haltech IG5
http://www.geocities.com/jeg1976/car_home.html

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