it is .. ..
but .. although the engine management system controls the turbo vanes ..
and the egr valve .. via the vacuum system and its solenoids
would the management system change its behaviour towards the turbo vanes ..
if it 'knew' that the egr valve was 'closed' ? i.e. via the egr vacuum hose being blocked-off
( i don't have the answer btw

..
i'm assuming it still gets the egr solenoid to operate so it presents a vacuum depression
to the egr valve diaphram ..
but i sort of doubt it knows that the diaphram is stuck 'closed' .. as-it-were ..
( as in the case of an egr bypass/delete being fitted )
given 'no vacuum leaks' it will probably 'see' the system as operating normaly ..
.. there's no sensor to tell the engine management that exhaust gases Are being fed
to the intake manifold .. ( unless i've missed something )
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that's my theory anyway ..