Bypass install

[Jay Rabe]

 > > If  a bypass valve is routed from before the throttle body to before
 > > the turbo inlet, as I understand it should be, won't that cause a
 > > problem with the pressure forcing the throttle plate down to
 > > abruptly?   Just curious.
 >
 > No--  The purpose of the CBV is to release a pressure wave
 > that was *created* when the throttle closed abrubtly. It doesn't allow
 > air to move in such a way that it will exert pressure on the throttle
 > plate. --

The throttle plate measures air going through it.  The only way it goes down 
is if there is no more air being sucked by.  With the throttle closed, the 
plate will 'fall' almost all the way down (motor isn't sucking much air at 
all.  And if the car its being installed in has the fuel cut solenoid the 
plate will fall all the way down shutting off fuel when it sees closed 
throttle.  (it bypasses the airflow plate effectively shutting off fuel, an 
emission & fuel saving thing)  The bypass being open in no way affects how 
much air the meter plate is seeing because it only reads how much air the 
engine is sucking.  (I could see it reading wrong if you blew the air 
straight down on the airflow plate, or an air leak wich could make it go 
rich/lean depending on where the leak is.)  The bypass just loops the 
metered air around until the motor sucks air again.  Then the plate goes op 
again.
Getting rid/blocking of the fuel cut solenoid may help lag going from WOT in 
boost to closed throttle back to WOT boost.  It wouldn't run very rich if 
you did, CIS only supplys fuel that the cis plate senses, if there's air 
going by there should be fuel too.  The valve does save fuel though - 
whenever throttle is closed.


>I was referring to the metering plate in the fuel distributor.  It >would
>seem to me that a reverse flow might occur forcing the plate down.

Nope, not anything major anyways,  I'm sure you mean the just pressurized 
air, When its let out the turbo is still spinning.  The air that just got 
let out is sucked back into the turbo, etc. etc. untill the throttle is 
opened or the turbo stalls,  This would take quite some time but then you 
could breathe some air backwards.  There would be no demand for fuel 
anyways, Your enging is slowing you down during this time, you wouldn't want 
fuel squirt in now.
  The small amount of fuel you are worried about here most likely isnt being 
squirt in anyways without the bypass valve because the fuel cut-bypass valve 
would be open so there couldn't be any fuel going in.  Its strang to figure 
it out with air so maybe think of it as water?

I hope this helps,

Jay

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