the BOV has no purpose in controlling boost.
it simply opens when vacuum is applied to the signal line....
it SHOULD stay completely closed under any other conditions.
perhaps it is now farked and is leaking badly, so you are losing boost?
edit: the way it is mean tto work, the boost pressure pushes against piston, and that is held shut by spring and ref line boost.
what you had, was manifold air trying to enter thru the side of the BOV, and the spring and ref line had nothing pushing against them, so the BOV stayed closed.
the Ch CH CH might be because the side loading from the manifold air mmight have caused piston to bind?
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