3 Hard starting, white smoke and dying on deceleration

Phil Rose pjrose at frontiernet.net
Thu Nov 27 11:53:07 EST 2003

At 9:49 PM -0500 11/26/03, SuffolkD at aol.com wrote:
>Phil et all:
>By pass valve (N-something) on the lower turbo air hose (like we replace with
>samcos) ....
>Blow off on the EM............right?
>I goofed.  Meant By pass valve up front by IC
>-Scott by BOSTON

Yes, the wastegate valve on the EM bleeds exhaust away from the turbo 
to reduce the turbo speed, but, AFAIK, is not normally referred to as 
"blow off".

The usual operation of a "blow-off" valve, as I understand it, is to 
regulate boost by allowing pressurized manifold air to escape (blow 
off) into the atmosphere. The downside of these valves is to cause a 
loss of metered air and hence an overly enriched fuel mixture. That 
contrasts with the action of our cars' bypass valve, which opens to 
allow pressurized air on the outlet side of turbo to be redirected 
(bypassed) back into the inlet of the turbo. This  prevents a 
pressure surge in the IC/IM during deceleration (closed throttle), 
and it is accomplished without allowing the metered air to be "lost".


>  > Scott, I'm sure you didn't mean to imply that the oem turbo bypass
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Phil Rose
Rochester, NY
mailto:pjrose at frontiernet.net

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