Volvo turbo Control Pressure Regulator, help

Kris Weldy volvo4life at attbi.com
Wed Jan 16 08:32:30 GMT 2002


I lost the beginning of the thread-but why not raise the control pressure by
shimming it with washers-which increases fuel pressure by 2 psi per shim
added?Found right on the fuel distributor...Hope that helps or was remotely
close to the question asked.---Your friend,
Kris Weldy
Arlington Texas
88supra turbo auto 9.1 1/8th
aim :volvofam3     --
yahoo:supratheonlywaytofly
www.turboboss.com
----- Original Message -----
From: "The Dupuis" <dupuis10 at telusplanet.net>
To: <diy_efi at diy-efi.org>
Sent: Monday, January 07, 2002 7:52 PM
Subject: RE: Volvo turbo Control Pressure Regulator, help


> I got'cha!
>
> Take a manifold pressure reference (Boost and vacuum), feed it to some
kind
> of a ported thermal vacuum valve that is open when cold (or use a Dodge
> Turbo vacuum solenoid and a toggle switch), feed the other end of the
> valve/solenoid to one end of a tee.  The second end of the tee goes
directly
> to the top port on the CPR, and the third end of the tee goes through a
> check valve, providing a constant vacuum to the bottom port.
>
> The idea is this:  When the engine is cold, the valve/solenoid is open,
> allowing a vacuum signal to the CPR.  This signal puts equal vacuum pull
on
> the top and the bottom of the piston inside the CPR.  When you are idling
or
> at high vacuum, this piston stays in the top position, which adds pressure
> through a spring to the CPR valve, raising the control pressure, leaning
the
> mixture.  When you open the throttle the vacuum falls away from the top of
> the piston but is held in the bottom of the piston by the check valve,
which
> draws this piston downwards.  This releases the spring pressure, lowers
the
> control pressure, and enriches the mixture.
>
> When the engine warms up, the valve/solenoid closes, which shuts off the
> vacuum signal to the CPR, and any difference will eventually equalize
> through the slightly leaky check valve or CPR piston, so the piston
returns
> to the top of it's stroke, pushing the spring into the fuel pressure
valve,
> raising control pressure, leaning it back out.
>
> You might think "Wow, a boost-referenced enrichment!", but it's too much
> fuel unless the engine is dead cold, and even then if you get into boost
the
> engine loads up and chokes out.  When the engine is warm, the
valve/solenoid
> should be closed to keep the control pressure up.  There is a pressure
> switch set to 3 psi that enriches the mixture under boost, and if that's
not
> enough you can add another at 12 psi or so to trigger "terminal 11" on the
> computer.  I don't like t11 in my car - it prefers to be lean.
>
> Interesting use of a Volvo Turbo computer!  Maybe I'll throw that in my
> wife's Digifant Cabriolet when I upgrade to the Megasquirt.
>
> I can't do ASCII graphics, so if you want a sketch or a further
description
> I can provide it.  There are no really good pictures from manuals that I
> have seen.
>
> Matt
>
> p.s., if you have that kind of a CPR, I believe it's from an '83 or
earlier.
> My '83 has it, but the early '84 (non-intercooled) that I pulled my wiring
> harness from didn't.
>
> > -----Original Message-----
> > From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> > Behalf Of Stephen Webb
> > Sent: January 7, 2002 2:40 PM
> > To: diy_efi at diy-efi.org
> > Subject: Volvo turbo Control Pressure Regulator, help
> >
> >
> >
> > This isn't strictly an EFI question, and I've been hesitant to post the
> > question.  After spending many hours trying to figure out the answer,
I've
> > decided to ask here.
> >
> > I'm using the fuel injection (K-jetronic with lambda) from a 1984 (I
> > think) Volvo 240 turbo.  (The application is a VW cabriolet turbo)  The
> > control pressure regulator from the turbo is designed to enrich the
> > mixture under boost, but there are two vacuum ports on the side of the
> > unit.  I'm trying to figure out which one needs to be hooked to boost,
or
> > what the proper connection is.  Vacuum schematics from Volvo repair
manual
> > would be perfect.
> >
> > Thanks in advance.
> >
> > -Steve
> >
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