5ktq and Boost loss (after MC rebuild/upgrade & T3/K26 turbo) - it was bypass valve!

[Ben Swann]

[On Thursday, June 13, 2002 4:08 PM, Ken [SMTP:auditude at get.net] wrote:
>  << File: ATT00008.txt; charset = windows-1252 >>
Wow, I didn't even realize I typed "boost valve", instead of "bypass
valve".  Wierd.

[I wouldn't necessarily call the valve bad.  Are you sure you are taking
the vacuum signal from the correct place?  I understand some of the ports
on the intake manifold are not "vacuum" per se, but are some kind of
variable-with-throttle-position.  I would check that, since if you are
providing less than full intake manifold pressure on the vacuum port, it
might let it leak out.  Since your setup is so custom, it's possible the
vacuum signal is from the wrong source.]

<snippage>
Later,

Ken

Quoting Ben Swann <bswann at worldnet.att.net>:
>
> Allright!  Ken wins the lucky cigar!  It was the bypass valve.
> ]

I am taking the "vacuum source/signal" from the port at the bottom of the
throttle body.  I expect it read vacuum when there is vac and boost when
there is boost.

Where should I be taking it from?

Oops - you sent this just as I was typing that - looks like I had it hooked
up wrong as I did exactly the NO NO in CAPS below..

[On Thursday, June 13, 2002 4:14 PM, Ken [SMTP:auditude at get.net] wrote:
>  << File: ATT00009.txt; charset = windows-1252 >>
Regarding the vacuum source for the bypass valve:

Here's some quotes from SJM's site:

http://www.sjmautotechnik.com/turbo.html#bypass

"On the 10V Turbo engines in the 1986-90 5000TQ/200TQ when connecting a
hose to the Bypass Valve small fitting:

DO NOT USE THE SMALL VACUUM PORT ON THE INTAKE MANIFOLD NEAR/BELOW THE
THROTTLE VALVE TO GET INTAKE MANIFOLD VACUUM/BOOST.

THIS FITTING HAS PORTED VACUUM THAT CHANGES WITH THROTTLE OPENING AND WON'T
WORK.

DO NOT USE THE SMALL FITTING AT THE IDLE STABILIZER VALVE HOSE CONNECTION
EITHER, AS THIS CONNECTION GOES IN FRONT OF THE THROTTLE VALVE, AND DOES
NOT HAVE INTAKE MANIFOLD VACUUM."

I was actually thinking about how this may affect my SchrapnelKnobben mod,
since I think I may be using the ISV port for the source of my upper WG
pressure.  My WG might be doing weird or non-optimal stuff when I shift, I
don't know!  Any comments here would be welcome.]<<-Ken

Ben->>
OK - that doesn't tell me where to exactly, but it give 2 places not to.  I
can try the source I am using for my SchrapnelKnobben mod, which is a
bridge between the disconnected frequency valve port..I can provide more
details later - actually I think there is a picture on my site:
http://www.homestead.com/ben_swann/TurboMods.html

it is a little hard to make out, but the red colored hose is one side and
the other comes from..I'll get back to you on this.  My recollection is
that is actual pressure.

Well this perplexing saga is coming together finally.

Ben