# Audi 5K Turbo WUR



## Dr. Dave (Apr 12, 2002)

*Audi 5K Turbo WUR pressures question*

how much does the WUR reduce the control pressure with boost. Has anyone tested this with gauges ?


[Modified by Dr. Dave, 2:33 AM 12-24-2002]


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

anyone ?


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

The reason I ask is I've tested 2 used ones and have not found any difference in control pressure when I put 10 psi to the port. I did the test with the car running and warmed up, the WUR mounted in the stock location, hooked up to the lines, and with the electrical connection hooked up. Am I doing something wrong or have I just been unlucky.


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

anyone, anyone, 
Bueller, Bueller


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## AdidasCU (Jul 24, 2001)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

Dave... it may be a function of engine load.... Fuel pressure probably doesn't change at idle, and no car boosts 10 PSI at idle... Try hooking up the gauge, and test it WHILE DRIVING....


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (AdidasCU)*

I'll try it this week and report back !


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## vwdohc993 (Dec 4, 2001)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

IMed you


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## enginerd (Dec 15, 2001)

*Re: Audi 5K Turbo WUR pressures question (vwdohc993)*

I have noticed that the difference is between vacume and 0 psi, not between 0 and 10 psi. Its more of a no vaccume enrichment. If your doing your testing to ambient and then pressurizing it with a bicycle pump you will not see this change. Try sucking on it


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (enginerd)*

The one I have works , I just had the boost line hooked to the wrong port. I had to hook it up to the side port that is part of the aluminum housing, not the one that is brass that has a barb on it.
FYI 
55 psi fuel pressure ( control ) @ 0psi boost
35 psi fuel pressure @ 5psi boost
28 psi fuel pressure @ 8-10 psi boost


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## AdidasCU (Jul 24, 2001)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

So is it the big or small port on the side???? This would be huge for WUR turbo owners!


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (AdidasCU)*

On the WUR I have it was the LARGE side port that lowered control pressure ( richening the mixture ) and not the small port. This is why I always TEST TEST TEST before I commit to modifying cars.
Even when testing at idle ( with o2 sensor disconnected from the computer to eliminate frequency valve changes ) the A/F ratio would richen on my meter so I know for sure its richer.


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## AdidasCU (Jul 24, 2001)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

Wait... so less fuel pressure makes it MORE rich? I am all confused today... where is FP being measured?


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## Dr. Dave (Apr 12, 2002)

*Re: Audi 5K Turbo WUR pressures question (AdidasCU)*

less CONTROL pressure is richer, the SYSTEM pressure ( 68-78 psi ) remains constant. I measure the fuel presssure between the WUR and the fuel distributor as the Bentley manual shows. The control pressure is pressure that gives resistance to the air sensor plate so less control pressure = less resistance on the plate so a given unit of air will raise the plate more therefore flowing more fuel to the injectors and a richer mixture results.
Most FI systems are electronic and only have system pressure so that raises with boost for a richer mixture.
raising our system pressure would also richen up our motors but that is controlled by shims and a spring in the distributor and is a constant pressure.
If you look in the Bently manual at the WUR specs it will show that on a cold start ( when rich is needed ) the wur is around 20 psi and raises as the motor warms up to 50-55 ( leaner as the motor warms )


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## imaradiostar (May 4, 2002)

*Re: Audi 5K Turbo WUR pressures question (Dr. Dave)*

There's a cool diagram in the Bosch FI and EM book that shows all the different styles of vacuum sensitive WUR's. That may be useful to some poeple. If I had a scanner I'd scan it and e-mail it to you.
Back in the day there were rising rate fuel pressure regulators that could be added to our CIS cars that would increase system pressure allowing greater overall fueling. Supposedly they worked very well.
I look at it this way- given stock system pressure and boost-sensitive WUR, a stock US rabbit GTI FD should be good to about 170 hp, less on a turbo car. With increased system pressure the available fuel at any given air flapper position will increase. 
You can't just increase the system pressure 100% of the time because then the car won't idle. I found this out the hard way on my GTI. I shimmed the FD in hopes of increasing fueling (which it did) but I couldn't get the car to idle anymore because the FD wouldn't correctly meter the fuel with the system pressure too high.
With a rising rate FPR added after the FD, you can increase system pressure only under boost so it doesn't negatively effect the system pressure when not on boost.
jamie


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## MHmotorsport (Nov 9, 2006)

*Re: Audi 5K Turbo WUR pressures question (imaradiostar)*


_Quote, originally posted by *imaradiostar* »_There's a cool diagram in the Bosch FI and EM book that shows all the different styles of vacuum sensitive WUR's. That may be useful to some poeple. If I had a scanner I'd scan it and e-mail it to you.
Back in the day there were rising rate fuel pressure regulators that could be added to our CIS cars that would increase system pressure allowing greater overall fueling. Supposedly they worked very well.
I look at it this way- given stock system pressure and boost-sensitive WUR, a stock US rabbit GTI FD should be good to about 170 hp, less on a turbo car. With increased system pressure the available fuel at any given air flapper position will increase. 
You can't just increase the system pressure 100% of the time because then the car won't idle. I found this out the hard way on my GTI. I shimmed the FD in hopes of increasing fueling (which it did) but I couldn't get the car to idle anymore because the FD wouldn't correctly meter the fuel with the system pressure too high.
With a rising rate FPR added after the FD, you can increase system pressure only under boost so it doesn't negatively effect the system pressure when not on boost.
jamie

Ok, this is a very old topic, but this is extremely interesting...
Anyone have any more info on this... what does it look like, how can i make this etc ?


_Modified by MHmotorsport at 3:50 AM 12-11-2006_


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## thegave (Dec 22, 2008)

Sorry mega bump but just to be clear it is the upper port shown here that I should be plumbing the vac line for if I want the control pressure to drop under boost?


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## thegave (Dec 22, 2008)

Was able to test it with a bike/ball pump and can confirm that it is the upper port that reacts to 'boost,' which dropped the control pressure quite significantly.

The lower port seemed to not respond to boost or vacuum. I did not try vacuum on the upper port because I have no reliable way of hooking up a hose. Maybe I could have sucked* through the pump needle..

Good info to know because very counter intuitive. Now need to find an appropriate barb it fit in the hole.


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## 134hpvw (Sep 6, 2013)

cool. keep the cis turbo technology going.


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