# Is anyone here running an adjustable digital WUR?



## RubensRoc (Feb 12, 2005)

I'm thinking of installing this in order to achieve some control from a vacuum source. 
Clicky clicky.....
http://unwiredtools.com/utcis-v.asp


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## Southcross (Jul 2, 2004)

*FV-QR*

we had a thread about those products about a year ago... I'd be willing to try it if I could afford it LOL


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## BSD (Jul 8, 2008)

I know right? I like CIS, but for 500 bucks I could run an entire MS setup. Haha
Steve-


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## Southcross (Jul 2, 2004)

*FV-QR*

I'm one of the few CIS supporters that _would_ try something like that... hell, I'm even contemplating a variant of MS to control CIS in place of the Lambda ECU


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## johnnyGO (Feb 23, 2009)

You can find a 10v turbo motor for the same or lower price then that. Then just spend the left over money you will have to get the ECU chipped, heavy gate spring and IC straps.... BAM, now you have 240hp


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## antichristonwheels (Jun 14, 2001)

*Re: Is anyone here running an adjustable digital WUR? (RubensRoc)*

What a cool designer part. Can I buy a knockoff in Chinatown? Honestly that is way cool. Wish that was around 20 years ago, they would have made a mint.


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## RubensRoc (Feb 12, 2005)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_I'm one of the few CIS supporters that _would_ try something like that... hell, I'm even contemplating a variant of MS to control CIS in place of the Lambda ECU

The MS sounds interesting. The reason I like this new product is it allows you to keep your CIS. I know it's not as flexible as a nice stand alone but I like the idea of keeping my engine bay somewhat vintage. I've thought about ITT controlled with a TEC II but I just can't give up the factory look. I still want control of my CIS and the UTCIS offers the best of both worlds.


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## RubensRoc (Feb 12, 2005)

*Re: Is anyone here running an adjustable digital WUR? (antichristonwheels)*


_Quote, originally posted by *antichristonwheels* »_What a cool designer part. Can I buy a knockoff in Chinatown? Honestly that is way cool. Wish that was around 20 years ago, they would have made a mint.

Yeah, you can buy anything In Chinatown.
Better late than never......I'm going to try this one out.


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## chois (May 12, 2000)

Talked to them for a while last year. They may have something coming out soon for CIS-E applications as well. We considered testing this on a race application, but the conversation sort of died out. It would be interesting to try.


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## Tom A (Oct 20, 2004)

*Re: (chois)*

Wouldn't that only work on CIS basic cars? If you have CIS-Lamda you have full throttle enrichment anyway, from the switch on the throttle body.

_Quote, originally posted by *chois* »_Talked to them for a while last year. They may have something coming out soon for CIS-E applications as well. We considered testing this on a race application, but the conversation sort of died out. It would be interesting to try.
I thought about replacing my WUR with an off the shelf EFI Fuel pressure regulator if we ever had WUR problems on the race car, there are a bunch of them that are in the correct pressure range, like this one: http://store.summitracing.com/...earch
May be harder to start cold, but I could live with that. We didn't have any problems though, so I never investigated further.


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## Southcross (Jul 2, 2004)

*FV-QR*


_Quote, originally posted by *Tom A* »_Wouldn't that only work on CIS basic cars? If you have CIS-Lamda you have full throttle enrichment anyway, from the switch on the throttle body.
I thought about replacing my WUR with an off the shelf EFI Fuel pressure regulator if we ever had WUR problems on the race car, there are a bunch of them that are in the correct pressure range, like this one: http://store.summitracing.com/...earch
May be harder to start cold, but I could live with that. We didn't have any problems though, so I never investigated further.

uhm... you need to do a LOT more research on CIS and what "Control Pressure" is and what it does


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## Tom A (Oct 20, 2004)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_uhm... you need to do a LOT more research on CIS and what "Control Pressure" is and what it does









Well aware of what control pressure is, and what it does. Don't remember the range for my GTI, but on my 911 the warm control pressure spec is 3.4-3.8 Bar, so roughly 49-55 PSI, well within the range of the Holley Pressure regulator I linked (35-65 PSI). 
Like I mentioned you wouldn't have the lower cold control pressure from the WUR for cold starts, but with a well running engine with a functioning cold start injector, I don't think that is that big of a deal, particularly on a race car. Unless it is very cold outside, the WUR will be at warm control pressure within a few minutes anyway.
The vacuum enrichment works by lowering control pressure under load, lower control pressure = richer mixture
The CIS Lamda system does the same thing using a full throttle switch on the throttle body, making the Lamda system run open loop, increasing the duty cycle of the frequency valve and enriching the mixture. 
Evidently I was wrong though on one point, some cars do use both methods for full throttle enrichment, my 911 has a VAC enrichment on the WUR, as well as the full throttle switch on the TB. I can't check the race car, but I don't believe it has a vac line to the WUR.


_Modified by Tom A at 11:15 AM 5-8-2009_


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## Southcross (Jul 2, 2004)

*FV-QR*

obviously not if you think a single static FPR is going to work as a control pressure regulator
look at a CIS diagram and tell me HOW that regulator will regulate the pressure on the top AND bottom of the distributor... i.e. CONTROL PRESSURE










_Modified by Southcross at 12:49 PM 5-8-2009_


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## chois (May 12, 2000)

I think you need to do some research on the function and purpose of the warm up regulator - since this is what he is talking about changing. The control pressure is still primarily changed by the flow plate position in either case.


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## Southcross (Jul 2, 2004)

*FV-QR*

The WUR is the primary valve that controls the "Control Pressure" you can't just delete it from the system or expect a single direction "dead head" FPR to do the same thing


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## Tom A (Oct 20, 2004)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_look at a CIS diagram and tell me HOW that regulator will regulate the pressure on the top AND bottom of the distributor... i.e. CONTROL PRESSURE









That is not how it works. If you have a CIS diagram or any documentation showing the WUR effecting system pressure, I would love to see it.
Control pressure is only the top of the FD, the bottom is system pressure, set by the regulator built into the fuel distributor.
If control pressure was both sides (Top and Bottom) of the control plunger, lowering the control pressure would have no effect on the mixture.
The return line from the WUR does return to Fuel Distributor, but that has nothing to do with pressure, it simply joins behind the system pressure reg so they can use a common return line to the fuel tank.
Example: from: http://www.diagnostic-assistan...j.htm








"B" To warm up regulator
"C" From warm up regulator
"F" Return to fuel tank
You will notice "C" is behind the Primary Pressure Regulator, where is joins the extra fuel from that regulator to return to the tank.
From the same page:








"A" Vacuum connection 
"B" Return to fuel tank
"C" Control pressure (from fuel distributor)

_Quote, originally posted by *Southcross* »_The WUR is the primary valve that controls the "Control Pressure" you can't just delete it from the system or expect a single direction "dead head" FPR to do the same thing
The regulator I linked is not a dead head, it is a return type, which for all practical purposes is what the WUR is. This link may work better:
http://store.summitracing.com/...w=sku
The only difference is that you would lose cold start enrichment.


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## Southcross (Jul 2, 2004)

*FV-QR*








go for it... I want to see you post back when you get it to work

_Quote »_That is not how it works. If you have a CIS diagram or any documentation showing the WUR effecting system pressure, I would love to see it.

buy a bentley


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## Tom A (Oct 20, 2004)

*Re: FV-QR (Southcross)*

I have 2 of them, plus the factory service manuals from Porsche and the Probst book. They all say the same thing.








Warm control pressure is static. Once your car is warm, control pressure does not change, except slightly from the Vac enrichment on some WURs.
System pressure is set in the fuel distributor, and is adjusted by shimming the spring in the regulator.
You do not know what you are talking about.


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## Southcross (Jul 2, 2004)

*FV-QR*

OK... I'll give you a little hint. The control pressure is a Differential pressure, you must maintain a certain differential between the top and bottom chambers regardless of what the base pressure is.... hence why there are TWO lines on the Control Pressure Regluator (aka Warm Up Regulator), the truth of the matter is "Warm up" is only a tini-tiny function of what that block on the front of your block is for...


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## Southcross (Jul 2, 2004)

*FV-QR*

+1
besides.... if you can come up with something that no one has thought to do in the 3 decades since Bosch invented CIS... your a better Engineer and should be making bomb casings for China


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## chois (May 12, 2000)

There are two lines to feed fuel to and from the unit. Warmup is one of two functions, the other being accelleration enrichement - via the load (vaccum line) signal. It just bleeds pressure off the top chamber to reduce resistance and let the control plunger rise more for more fuel.
As for an idea not being any good just because no one else came up with it yet, my job is R&D. You would be surprised at how many new ideas we still come up with in an industry that has been very stable technologically over the past 3 decades. The best ideas always seem simple AFTER someone finds them.


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## Southcross (Jul 2, 2004)

*FV-QR*

ya... maybe run some 100 octane, that will make it work


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## Southcross (Jul 2, 2004)

*FV-QR*

tell you what, since you work in R&D...
design a pressure regulator that regulates the correct pressure differential between the upper and lower chambers (I'll let you research that value on your own as I don't have my book sitting in font of me







)... and if it doesn't happen to look like the Bosch unit, good for you

FYI, if your so concerned about the "warm up" not working right for you... just unbolt the ****ing thing from your block


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## Tom A (Oct 20, 2004)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_ buy a bentley









From the Bentley book for Rabbit, Scirocco, Jetta, 80-84, page 4-5, Fig 1-1








Clearly shows the return line from the WUR goes back to the tank.
Same page, Fig 1-2, including the Lamda system








Also clearly shows the return line from the WUR goes back to the tank.
Both of them show the fuel flow, but omit the push valve in the FD. 
Here is a diagram of what happens to the fuel from the WUR return line where it hits the FD, from the Book "Bosch Fuel Injection & Engine Management" by Charles Probst.








When the engine is running, system pressure pushes the valve open, allowing the excess fuel from the WUR to return to the tank. When the engine is off, the valve closes, keeping control pressure from bleeding off. That is all it does.

_Quote, originally posted by *Southcross* »_OK... I'll give you a little hint. The control pressure is a Differential pressure, you must maintain a certain differential between the top and bottom chambers regardless of what the base pressure is....

What do you mean "base pressure"? You are correct in that there is a differential in the 2 pressures, act on opposite sides of the control piston, but only one of them comes from the WUR. Control pressure acts on the top, system pressure on the bottom. 
Here is the diagram from the Probst book, Chap 5, p19:








System pressure is constant, controlled by the regulator in the fuel distributor. Control pressure is generally constant (except as noted below), once the heating element in the WUR is up to temperature, according to the Bentley book, (Page 4-36) should happen about 2 minutes after starting the car. 
Lower control pressure above the control piston means less resistance to the sensor plate rising, allowing the plate to rise higher for a given airflow, richening the mixture. 
Once the warm control pressure is reached, (again, ~2 minutes after engine start) the control pressure should remain constant, unless you have a WUR with a vacuum connection.
For those WURs that do have Vacuum or Boost enrichment, this is how it works, again from "Bosch Fuel Injection & Engine Management" by Charles Probst.:









_Quote »_ hence why there are TWO lines on the Control Pressure Regluator (aka Warm Up Regulator), 
As noted above, the second line is the return line. All it does is return fuel to the tank. It is essentially a return type fuel pressure regulator, with some temp based rising pressure rate built in. Pretty clever little box.

_Quote »_ the truth of the matter is "Warm up" is only a tini-tiny function of what that block on the front of your block is for...








I assume you are referring to full throttle or boost enrichment. The WUR on the race car does not have a vac line, so I never looked in to it that much. For that style to quote Mr Probst above "Warm up compensation was it's only job" and full throttle enrichment happens by increasing the duty cycle of the frequency valve, triggered by the full throttle switch on the throttle body. On the race car, I don't care about Full throttle enrichment, we removed the switch and jumpered the wires so we had it all the time, then set the mixture on the dyno. 
My 911 appears to have both, it has a vacuum line to the WUR, and the full throttle switch. The Probst book mentions testing the vacuum enrichment, but says to refer to your shop manual for specs. The 911 Bentley book covers CIS in detail, but does not mention that test, and I don't remember seeing it in the factory shop manuals, but I wasn't really looking for it.
I am curious how much it actually effects the control pressure. Have to try it out the next time I have the CIS gauges hooked up. I don't expect it does all that much, maybe a few PSI. I could be wrong though.
Does anyone have any data on how much the vacuum WURs effect control pressure under load?

_Quote, originally posted by *Southcross* »_tell you what, since you work in R&D...
design a pressure regulator that regulates the correct pressure differential between the upper and lower chambers (I'll let you research that value on your own as I don't have my book sitting in font of me







)... and if it doesn't happen to look like the Bosch unit, good for you
That is not what the WUR does. All it cares about it the control pressure. It is your job to make sure the differential is correct, by measuring the system pressure and cold/warm control pressures to make sure they are in spec.

_Quote »_FYI, if your so concerned about the "warm up" not working right for you... just unbolt the ****ing thing from your block









I was not concerned with the "warm up" portion. I specifically mentioned that using a standard fuel pressure reg would not provide cold start enrichment, and that since my application was a race car, I didn't care. We never had problems with the WUR, and the stock system provided plenty of fuel for our mods, so we left it alone. 
So back to the original subject, I suppose that if you have a car that has neither vacuum enrichment on the WUR or from the Lamda system, or your WUR is not working properly, that looks like a cool system.


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## chois (May 12, 2000)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_tell you what, since you work in R&D...
design a pressure regulator that regulates the correct pressure differential between the upper and lower chambers (I'll let you research that value on your own as I don't have my book sitting in font of me







)... and if it doesn't happen to look like the Bosch unit, good for you


Are you always this nice to have a conversation with? Thats the whole point of this end of the conversation. That it looks like you could do exactly what the system needs to run, and make it very easily adjustable on the dyno for desired afr (though without any warmup enrichment) with a commercially available part. The new idea is to use that, not to invent it again.
FWIW I find it easier to just use a CIS-E and alter the CTS signal to tune the afr. It is very easy to set up and tune, and the aluminum fuel distributor has quite a weight advantage over the steel CIS stuff.


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## Tom A (Oct 20, 2004)

*Re: FV-QR (Tom A)*


_Quote, originally posted by *Tom A* »_
My 911 appears to have both, it has a vacuum line to the WUR, and the full throttle switch. 

OK, after doing a fair bit of digging, it turns out that on my model of 911, the vacuum line is just a vent, and the hose routed to the intake tract to keep it clean/dry.








There are enough flavors of CIS out there, this probably applies to others as well.
Looking again in the Bentley and Porsche factory manuals for the CIS basic versions, there is a listed warm control pressure with and without vacuum attached, and the difference is shown as 1/2 bar, so ~7.25 PSI.
Which going back to the original post, if you have CIS-Lamda, you already have full throttle enrichment provided by the Lamda system. If you have CIS basic, you probably have full load enrichment from your WUR.
No doubt the Digital WUR provides the ability to tune this enrichment, as well as tweaking your control pressures (if needed) much easier than with a standard WUR.
Whether this is worth $500, is up to you.


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## Uberocco83 (Jul 15, 2008)

*Re: Is anyone here running an adjustable digital WUR? (RubensRoc)*

I bought one a little while back and Im going to get the utcis-v for my 16v build running soon and I will for sure post up results. $500 was a lot but its so simple, clean and unique. I think proper tuned cis-e runs very well but I dont like the switches and relays for enrichment........we will see how this compares.


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