[urq] WUR findings - Warmup Pressure Regulator

John Cody Forbes cody at 5000tq.com
Thu Mar 26 15:50:16 PDT 2009

That reminds me. I recomend the following product as a very nice 
upgrade/replacement to a WUR:

No affiliation etc, just a very satisfied user and multiple-instance 


Dag Bøsterud wrote:
> It is possible to use the WUR to enrichen the mixture under turbo
> pressure, but you would need a so called three stage WUR for this.
> A couple of years back I was thinking of doing a turbo project on a
> car I own, and bought such a WUR for this car.
> This car uses simple CIS / K-Jetronic. The WUR is adjustable, and it
> also has the ability to give extra fuel when under positive pressure
> as
> under negative pressure.
> The company I bought this WUR from is http://www.enginetuner.co.uk/ -
> ask for Alan Jeffries.
> /Dag
> 1990 100 TQ Sport Exklusiv
> ----- Original Message -----
> From: "Ben Swann" <benswann at verizon.net>
> To: "'Bares, Vittorio'" <Vittorio.Bares at nuance.com>;
> <gmbchef at sbcglobal.net> Cc: <quattro at audifans.com>
> Sent: Thursday, March 26, 2009 10:09 PM
> Subject: RE: [urq] WUR findings - Warmup Pressure Regulator
>> I just sent a reply to Cody, so read that for a little more info.
>> It is helpful to read
>> the Bentley to gain some details on the various CIS and CIS-E
>> systems.  To really get
>> the whole story, BOSCH Fuel Injection by Probst is the required
>> bedtime reading.
>> WUR - Warmup Regulator
>> WUP - something one used to get when they were naughty.  I think was
>> a typo, but could
>> perhaps mean Warmup Pressure
>> WCUPR - A little harder to type, but actully more accurate meaning
>> Warmup Control
>> Pressure Regulator and should probably be WUCPR or just CPR which
>> might get confused
>> with something that is done then a heart stops beating.
>> CWPUR - probably another variation on the above.
>> Most folks call it the WUR or CPR.  In short this device has been
>> used on CIS based cars
>> since the 70's or before when Bosch fuel injection came about.  It
>> regulates the control
>> pressure that acts as a counterforce in the fuel metering head.  By
>> controlling this
>> pressure as the car warms up and also for load related condition
>> (manifold preesure) the
>> fuel mixtrue can be enriched for cold starting or heavy load, or
>> enleaned as the engine
>> warms up or is cruising.  The devil is in the details.
>> Ben
>> -----Original Message-----
>> From: Bares, Vittorio [mailto:Vittorio.Bares at nuance.com]
>> Sent: Thursday, March 26, 2009 3:46 PM
>> To: Ben Swann; gmbchef at sbcglobal.net
>> Cc: quattro at audifans.com
>> Subject: RE: [urq] WUR findings
>> I feel dumb...what is:
>> -- WUR
>> -- WUP
>> -- WCUPR
>> -- CWPUR
>> Unless they are the sounds of my car makes when its not working
>> right ;)
>> Vittorio -
>> -----Original Message-----
>> From: quattro-bounces at audifans.com
>> [mailto:quattro-bounces at audifans.com] On Behalf Of Ben Swann
>> Sent: Thursday, March 26, 2009 3:36 PM
>> To: gmbchef at sbcglobal.net
>> Cc: quattro at audifans.com
>> Subject: [urq] WUR findings
>> Gary,
>> Without remembering exact  specifics on this, I'll give you enough
>> info. to support
>> advice to leave the hose routing as indicated in the stock layout.
>> Basically the WUR has two port on it - one provide pressure to the
>> side of the diaphragm
>> that enriches and the other to the side that enleans.  Once the temp
>> valve opens, the
>> circuit allows to enrich and enlean based on manifold pressure.  It
>> seems counterintuitive at first that both sides of the WUR are
>> plumbed into the same pressure
>> - wouldn't that cancel out any effect of pressure you likely
>> wondered.
>> Me too, so I did
>> some experimenting and somewhere I have notes on the results.
>> What actually happens is the amount of force on the diaphragm is
>> disproportional.  As I
>> recall, the port has greater effect on riching up the mixture than
>> is does to lean, but
>> that is the part I forget exactly and it may be backward.
>> I played with this thinking I could get more enrichment by
>> separating out the two and
>> using other pressure sources - one of them was the venturi effect
>> off the throttle and
>> there is one off the turbo hose too, as well as some valves and
>> manifold source, and use
>> of an air fuel meter.  These all met with various and interesting
>> results, but mostly my
>> conclusion in the end was to fix what is broke with the stock system
>> and leave the WUR
>> plumbing as it was.  With that you could use the WUR to provide
>> enrichment for greater
>> fuel at boost, but it is very hard to control with simple valves.
>> The best way to add fuel if you are upping the boost is some sort of
>> EFI - a
>> supplementary injector does fine for modest power levels under 300
>> HP and full EFI like
>> what I did using Megasquirt to dial in as much boost and fuel as you
>> can safely with
>> your turbo and other setup.  You can also shim the air flow meter,
>> but that IMO is a
>> temporary workaround.
>> I like CIS, but I like EFI better.
>> Ben
>> [Date: Thu, 26 Mar 2009 08:45:41 -0700 (PDT)
>> From: Gary Brown <gmbchef at sbcglobal.net>
>> Subject: [urq] WUR findings
>> To: urq at audifans.com
>> Message-ID: <84785.75341.qm at web82101.mail.mud.yahoo.com>
>> Content-Type: text/plain; charset=us-ascii
>> A few weeks ago I was having leaning condition under high boost.
>> Everything was working
>> as they should, and found that the wastegate actuation stud was
>> stripped, causing the
>> diaphragm to lift, letting the boost spike. Fixed that, same problem.
>> So...after lots of
>> urq list archiving and remembering some of the Bosch book topics, I
>> remembered that the
>> WUP on this car was set up for cold running as well as boost
>> enrichment, but the hose
>> set up made no sense to me. I have tinkered with that before, but
>> never quite figured it
>> out. This time, I took an old WUP (CPR) apart, and applied pressure
>> to both nipples then
>> vacuum to both nipples. What I found was that the two nipples are
>> placed in such a way
>> that the diaphragm moves the same direction under boost as well as
>> vaccum, the large one
>> being the boost enrichment. What didn't make sense is the on-off
>> switch below #5
>> cylinder plug, with the two nipples on it. It has one hose from the
>> manifold going to
>> it, and  one hose that is teed off to go to both the large and small
>> nipples on the
>> WCUPR. When the motor gets warm, the switch closes, and therefore no
>> vacuum or pressure
>> goes to the CWPUR. This is as per the underhood and IST docs.
>> So....I by passed the
>> switch all together...guess what....enrichment under high boost!
>> But, now enrichment
>> under decel too. When I re-install the vacuum hose from the manifold
>> to the switch and
>> the switch to the small nipple, that will take care of that. But, it
>> does sound cool
>> with that rolling burble under in-gear decel! I'm sure that this has
>> been written up
>> somewhere, but I couldn't find it.
>> HTH
>> Gary ]
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