WUR/CPR was Re: [urq] Parts recommendations

[Ingo Rautenberg]

Jim,

I know what Ben is referring to.  Unfortunately, none of the ETKA diagrams
accurately pictures this.  On my car (Ben's as well -- and probably all
other WX motors) the FPR/WR has two vacuum ports nearest the engine block,
one being approx 1/4" whereas the other more closely approximates 3/16".
Curiously, there is a tee combining them and then leading to the
thermo-pneumatic valve.  Maybe just another kluge (aka dumbass) modification
to make this part work on the WX motor --most likely a carry-over from the
previous US type 43 5k turbo.  Should only really require one vacuum
connection, IMO.

HTH

Ingo

----- Original Message ----- 
From: "James Howard" <spam.me1 at ntlworld.com>
To: "Ben Swann" <benswann at comcast.net>
Cc: <urq at audifans.com>
Sent: Wednesday, March 30, 2005 4:49 AM
Subject: Re: WUR/CPR was Re: [urq] Parts recommendations


> Hi Ben,
>
> On the WR at least the layout is like this:-
>
> http://homepage.ntlworld.com/jh.666/diag.jpg
>
> When you say 2 lines going to CPR do you mean the 2 Teed together as per
> this diagram?
>
> The way I understand it the WR system works as below - I think the WX is
> pretty much the same at least as far as warm up goes, not so sure about
WOT
> 'cause of the whole frequency valve part on the WX - but I did think that
> the duty cycle was maxed out by about 4000rpm (it is on the MB).
>
> When the engine is cold, the thermo valve is open and the mixture is
varied
> as the amount of vacuum applied to the CPR varies. - The more vacuum
applied
> (ie closed throttle/overrun) the higher the control pressure and the
leaner
> the mixture.
> The 'base' control pressure is lower anyway as the secondary function of
the
> CPR is to vary pressure with temperature.
>
> When the engine is hot, the base control pressure is higher (because the
CPR
> is hot) and the thermo valve is shut. In a non-WOT condition, only vacuum
is
> applied (and held) on the CPR via the one way valve and the top connection
> of the solenoid valve.
> During WOT the solenoid opens and positive pressure is then applied to the
> CPR  via the bottom connection to the solenoid valve to lower the control
> pressure and provide WOT enrichment.
>
> Basically this vacuum system provides enrichment at partial throttle on a
> cold engine, and enrichment only at WOT on a hot engine.
>
> I have done some tests on my CPR with a MightyVac and a fuel pressure
gauge.
> As vacuum is applied to the CPR, the control pressure rises. Applying
> positive pressure to the CPR does nothing - the control pressure is
already
> at it's minimum at atmospheric pressure. The vacuum system on the car
> appears to apply positive pressure to the CPR only to dispell the vacuum.
>
> This may give some clues too, although it's WR again :-
> http://www.isham-research.co.uk/quattro/wr_hoses.html
>
> Jim.
> ----- Original Message ----- 
> From: "Ben Swann" <benswann at comcast.net>
> To: <spam.me1 at ntlworld.com>
> Cc: <urq at audifans.com>
> Sent: Wednesday, March 30, 2005 3:27 AM
> Subject: WUR/CPR was Re: [urq] Parts recommendations
>
>
> > Jim,
> >
> > I thought the valve opened on warmup.  Anyhow- you are probably right.
> > Just
> > trying to understand how this operates better.
> >
> > I was wondering is there a sensible way to re-plum this to provide
greater
> > enrichment under boost.
> >
> > Also - there are two lines on the CPR/WUR.  Do you know how they
operate?
> > I
> > was just redoing the vacuum lines on mine and was puzzled why they did
it
> > this way and why both ports are used for the thermo-time switch control.
> >
> > Ben
> >
> > [Date: Tue, 29 Mar 2005 19:46:19 +0100
> > From: "James Howard" <spam.me1 at ntlworld.com>
> > Subject: Re: [urq] Parts recommendations
> > To: "Ingo Rautenberg" <i.rautenberg at waratap.com>, <urq at audifans.com>
> > Message-ID: <006301c5348f$99fd9e30$657ba8c0 at jim>
> > Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> > reply-type=original
> >
> > The thermo valve closes as the engine warms up.
> > When the engine is cold, the valve is open and fuel control pressure
> > varies
> > with vacuum.
> > When the engine is hot, the valve is closed and full vacuum is held on
the
> > control pressure reg (after the 1st decel) until a WOT event when the 2
> > way
> > valve on the bulkhead opens and positive pressure is allowed through to
> > dispell the vacuum.
> >
> > The control pressure reg does not enrichen further on boost, only leans
on
> > vac - it is at full enrichment travel at atmospheric pressure.
> >
> > Ergo, without the thermo valve, you have no cold running or WOT
enrichment
> > control, as the control pressure reg will be maxed out at part throttle
> > even
> > with a hot engine.
> >
> > Jim.]
> >
>
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