WUR/CPR was Re: [urq] Parts recommendations

Thu Mar 31 19:14:44 EST 2005

I found what sounds like the explanation in a page from my 911 bookmarks
(in the part about lambda sensors):

"Drops control pressure when engine is cold, resulting in a richer 
mixture during
  warm up. . The term warm-up regulator is a bit of a misnomer in that this
  component actually regulates control pressure the entire time the 
engine is running.
  It changes the pressure during the warm-up period. Power is applied to 
bimetal
  strip in the regulator when fuel pump is on. As the internal resistor 
heats up the
  strip, the control pressure supplied to the fuel distributor 
increases, leaning the fuel
  mixture. On cars with vacuum control, the WUR enriches mixture under load
  determined by lower intake manifold vacuum. Some versions also modify 
pressure
  with altitude. Lambda sensor systems don't use the vacuum chamber 
because of
  this adjustment being automatically accomplished by the lambda system 
electronics
  box. '81 saw a change in the internal resistor configuration for the 
WUR. A second
  resistor was added to heat the bimetallic spring, controlled by a 
bimetallic switch.
  This allows the mixture to lean out more quickly after start-up,about 
2 minutes
  compared to the former 3 minutes."

Many 911s and 930s use both lines, I've heard some SC guys say they've 
used 5000 parts
and passed emissions so there is some compatibility to be found between 
Audi/Porsche
specs.

This page is 911 oriented, but may give some more insights:
http://members.rennlist.com/jimwms/CIS/CIShome.html

Charlie

Ben Swann wrote:

>Hey - I was looking a Huw's diagram.  This makes more sense, but I don't get
>it yet.
>
>See: http://www.humanspeakers.com/audi/vacuum-system.htm
>
>Knowing what each CPR port does would clarify - quattro list in copy in case
>anyone knows there - Huw?
>
>This includes a valve  between the larger of the two CPR lines and the tee
>and another line directly to manifold.
>
>Hmmm - wonder what is going on here.  One must be for vacuum and the other
>for positive pressure, or ???
>
>Ben
>----- Original Message -----
>From: "Ben Swann" <benswann at comcast.net>
>To: "Ingo Rautenberg" <i.rautenberg at waratap.com>; "James Howard"
><spam.me1 at ntlworld.com>
>Cc: <urq at audifans.com>
>Sent: Wednesday, March 30, 2005 12:45 PM
>Subject: Re: WUR/CPR was Re: [urq] Parts recommendations
>[Ingo describes what I was talking about , and it just didn't make sense to
>me.  To simplify - on my '83(as per diagram under hood)  a line comes off
>the thermo time valve/switch and tees off to the 2(two) ports on the CPR -
>if the valve is open, then you get manifold pressure, if it is closed then
>does nothing.  Perhaps some re-teeing or one way valving can be applied to
>make this work better.  My engine seems to be running lean on startup and at
>boost, and I beleive it is the CPR - yes fuel pressure test is in order.
>Was hoping to try a WUR/CPR from an '83 CGT NA (not turbo) as they look
>identical, but have not checked the numbers.  Anyone know offhand?
>
>My setup is not like: http://homepage.ntlworld.com/jh.666/diag.jpg but like
>Ingo says - what do the two different ports do specifically - thought one
>actually facilitated enrichment under boost.
>
>I thought this WUR could be used to facilitate higher fuel pressure at boost
>by lowering control pressure, but from what jim says is not the case.  Also
>if the thermo time swith closes rather than opens as the engine warms, then
>the tee'd off lines do nothing once the engine is warm - so this could
>probably be improved upon.
>
>Uh what is thermo-pneumatic valve?  Maybe it is supposed to work somewhat
>with pressure too and not just a temp switch.  Why two ports then?  Does one
>work under vacuum and one under boost - which is kind of what I thought.
>
>Ben
>
>text edited in earlier messages to remove >>garbage >> as they are one of my
>hangups in reading something.  Megots to get ETKA running and recover all my
>info - too much to dooo!
>
>----- Original Message -----
>From: "Ingo Rautenberg" <i.rautenberg at waratap.com>
>To: "James Howard" <spam.me1 at ntlworld.com>; "Ben Swann"
><benswann at comcast.net>
>Cc: <urq at audifans.com>
>Sent: Wednesday, March 30, 2005 9:56 AM
>Subject: Re: WUR/CPR was Re: [urq] Parts recommendations
>
>
>  
>
>>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 aboutWOT
>'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.] ....Snip...
>>>      
>>>
>
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