Wur

[delorean82]

While reading these posts reguarding rich fuel I keep seeing "clean out WUR".
What is a WUR?

[sdg3205]

WUR stands for warm up regulator, aka the CPR which stands for cold pressure regulator.

It's engaged when the car is cold.

It has a screen which can clog with debris and affect your warm-up.

It also has some wires inside that can burn out from what I hear.

It's located on the drivers side valve cover by the fire wall.

[Ron]

I think he meant CPR = Control Pressure Regulator (it's always working). :p

[WelmoedJ]

WUR stands for warm up regulator, aka the CPR which stands for cold pressure regulator.

Correct name is Control Pressure Regulator.
It's function is to control the fuel pressure (call it secondary fuel pressure as the primary pressure is set by the PPR).
It's also provided with an element that can be heated by 12V allowing the fuel regulation to adapt to cold start situations.
Hence the nickname WUR.

Welmoed.

[sdg3205]

Oops. My bad.

Divided attention and mixup with CSV - cold start valve. It's all in the abbreviation thread.

[Farrar]

If you look up the history of K-Jet you may find that on earlier implementations of the system (e.g. before Lambda) there was a Warm Up Regulator, but on our cars and all later K-Jet systems the unit is similar but takes a more active role (i.e. is activated all the time not just during warm-up), so it is called the Control Pressure Regulator. So you can think of it as "warm up regulator" being a predecessor to "control pressure regulator." A CPR is correct for a DeLorean, but (confusingly) some of the technical manuals still use the old term.

Farrar

[Ron]

FWIW: Bosch called them WURs on the Rabbit, Jetta, and the Capri (for sure- I had to a get data sheet, last week).

[Bitsyncmaster]

It's function is to make a richer mixture during warming up the engine but there is a vacuum line that may adjust mixture during acceleration even after warm up. I've not really paid much attention to the control pressure while punching the throttle.

[Szabi]

Hello, my WUR has recently been checked, the pressure is very low when cold, while it is OK when warm. A local mechanic says the pressure on the `cold side` of the WUR is not adjustable, therefore the WUR is not repairable. Is that true?
I found the following information in a Porsche-article:
Note that there is no obvious visible means of adjustment of either the hot or cold control
pressures. When you talk to JK however you find out how it’s done. The regulator unit
(iron) is pressed into the die cast WUR body, and it’s position determines the hot control
pressure. Similarly, the post that holds the bimetallic strip is pressed in to the die cast
body, and its position determines the effect the strip has when cold.

[sdg3205]

There is:

1. System pressure - standard operating pressure of k-jet

2. Control pressure - varied by WUR to accommodate mixture and engine performance.

Do you have the two pressures he found?

[Szabi]

There is:
1. System pressure - standard operating pressure of k-jet
2. Control pressure - varied by WUR to accommodate mixture and engine performance.
Do you have the two pressures he found?
No, but he showed me the Workshop Manual page D:02:01 with the control pressure values, and then he started the cold engine. The meter showed very low pressure (I don`t want to say anything stupid, but I think it was 0.5 - 0.75 Bar, not sure if that`s possible at all?), while the lowest value on the Manual`s diagram is 1.5 Bar. Either way, the actual control pressure was lower than what the Workshop Manual mentions.
And then the guy pointed at `warm` control pressure values in the Manual (3.4-3.8 Bar) saying that he measured the same value after warm-up.

[sdg3205]

Find out your system pressure. If system pressure is out to lunch you can't get accurate control pressure readings.

[DMCMW Dave]

Hello, my WUR has recently been checked, the pressure is very low when cold, while it is OK when warm. ]

That is normal operation.

[Ron]

No, but he showed me the Workshop Manual page D:02:01 with the control pressure values, and then he started the cold engine. The meter showed very low pressure (I don`t want to say anything stupid, but I think it was 0.5 - 0.75 Bar, not sure if that`s possible at all?), while the lowest value on the Manual`s diagram is 1.5 Bar. Either way, the actual control pressure was lower than what the Workshop Manual mentions.
And then the guy pointed at `warm` control pressure values in the Manual (3.4-3.8 Bar) saying that he measured the same value after warm-up.
$.02

First have the mechanic confirm PRIMARY Pressure (~5.2 Bar), as suggested above.

WARM pressure should be checked/adjusted next, which you report is OK (3.4-3.8 Bar).

Check COLD pressure last. Engine must be DEAD COLD (I.E. cooled over night), especially when making any COLD adjustment!
0.5 - 0.75 Bar is too low per specs for your current weather...but this will make it a little rich, which some like. If you're a picky ass WRT specs, like myself:

You must work fast because the engine heat will get to the WUR in seconds. Use the chart.
Assuming it is 20C (68F), the pressure should be 2.0-2.4 Bar, which means you need to raise the pressure.

To raise the COLD pressure, find a high grade bolt/screw that will thread into the hole circled below such that when it is bottomed out lightly, it leaves several threads exposed ( say ~1/4 "). Now remove the bolt and add 1/4" washers. Unplug the WUR. Start the engine and tighten the bolt -- It does not take much at all to bring the pressure up that much, so go slow enough to get it right the first time. No, slower than that..:wink:

http://dmctalk.org/attachment.php?attachmentid=35942&stc=1

To lower the COLD pressure, remove one of the washers and tap the bolt lightly to drive the assembly deeper. (Although pressed for time, DO NOT be tempted to do this w/o the washers as the assembly will probably go too far and damage an extremely thin portion of the casting!) Now, tighten the bolt to pull the assembly back outward to obtain the correct pressure as above. Again, this must be done when the engine is dead cold.
http://dmctalk.org/attachment.php?attachmentid=35943&stc=1


FYI- The WARM pressure can be set. It is not something most would want to try...Basically: It should be set before COLD pressure. Adjusting works the opposite way I.E. you drive the "plug" located on the bottom in to raise pressure (easy, but touchy) and out to lower pressure (a PITA because movements of 100th inch makes a big difference AND the unit needs to be disassembled to press the "plug" out to avoid sure destruction of other parts). Note: High WARM pressure is often a due to a clogged filter/screen.
A peek inside:
http://dmctalk.org/attachment.php?attachmentid=35945&stc=1

[FABombjoy]

That WUR seems to be missing some parts.

If warm control pressure is off and you've verified that the screens are clear, you can make adjustments without disassembly, "knocking the plug" or other adjustments to the parts pressed in to the upper case.

On the bottom is a brass cap. Drill a small hole in the center and you'll find a hex adjustment screw. Use a bit stop or use a grinder to cut the hole. This screw will change both cold & warm readings, but focus on warm first. This opens the lower chamber of the WUR to atmosphere so you'll need to seal this off once done or your cold vacuum enrichment won't function properly.

If you have good warm pressure but cold is still off, then you may need to investigate other options, but I'd start with measuring and adjusting a fully-warmed WUR.

[Ron]

That WUR seems to be missing some parts.

If warm control pressure is off and you've verified that the screens are clear, you can make adjustments without disassembly, "knocking the plug" or other adjustments to the parts pressed in to the upper case.

On the bottom is a brass cap. Drill a small hole in the center and you'll find a hex adjustment screw. Use a bit stop or use a grinder to cut the hole. This screw will change both cold & warm readings, but focus on warm first. This opens the lower chamber of the WUR to atmosphere so you'll need to seal this off once done or your cold vacuum enrichment won't function properly.

If you have good warm pressure but cold is still off, then you may need to investigate other options, but I'd start with measuring and adjusting a fully-warmed WUR.

The "brass cap" is in the 3rd pic above, upper left hand piece.
The hex head (allen hole) is in the lower left hand piece. It is used to hold the metal disk sandwiching the rubber portion of the diaphragm.
If you simply drill a hole and turn the hex head, the rubber portion of the diaphragm will be distorted if not torn...

These are the "missing parts":
http://dmctalk.org/attachment.php?attachmentid=35962&stc=1
They stack up on the metal piece sandwiching the diaphragm on the other side (see below).
Reverse side of lower left piece in previous post:
http://dmctalk.org/attachment.php?attachmentid=35963&stc=1
The innermost piece 'floats' and has the allen hole (on reverse side). The "brass cap"/plug serves as a stop (against other disk).
The 1st & 2nd pieces (from the left) in the "missing parts" pic above are springs, which counteract the larger spring shown in the center left of the 3rd pic in previous post....which is why you must set WARM pressure before COLD...

[FABombjoy]

If you simply drill a hole and turn the hex head, the rubber portion of the diaphragm will be distorted if not torn...
If that screw were seized I could see that but under normal circumstances it is perfectly adjustable. It does not need much effort to turn, so if it doesn't turn freely it would be worth disassembling the WUR to find out why.

I did 2 separate dyno sessions and a bunch of road logging (via LC1 and LMA-3) and tested the effects of changing control pressure on AFR. Multiple turns of adjustment. If my diaphragm was going to tear it would have been shredded long ago.

I'm really not the only one that's toyed with the adjustment screw:

http://forums.pelicanparts.com/porsche-911-technical-forum/91827-pics-warm-up-regulator-apart-adjusting-78-sc.html
http://forums.pelicanparts.com/porsche-911-technical-forum/91734-adjusting-warm-up-regulator-78-sc-you-gotta-read.html
http://www.928motorsports.com/parts/images/cis_regulator/CISReg2.jpg



which is why you must set WARM pressure before COLD...
100% agree. Unless someone has physically struck the WUR with a hammer or something, and if the heater isn't dead, setting warm pressure should fix cold as well. I unhibernated my car on a 0 degree day just to confirm, without a doubt, that the WUR was in full cold mode, and to verify correct cold control pressure.

[Ron]

OK, it's been a while so ya made me dig through my bones box and take another look... :confused2:

You were correct -- The screw in the WUR above was seizing up!
Looking it all over and considering the original assembly process, I am now wondering if the large cylinder in the top of the assembly should be moved instead because turning the screw would affect both warm and cold pressures AND the downward deflection of the diaphragm during cold acceleration (not used on the Porsche WUR shown). Seems there would be a lot less re-adjusting, from scratch anyway. I guess it depends on how touchy the deflection section is WRT a D anyway...
Either way it is a balancing act between the springs , diaphragms, and bi-metal arm...Something else to play with...

And THX!

=====

To avoid confusion (sorry)- If the Primary and WARM pressure is OK, using a bolt and washers, as above, is the way to go for setting the cold pressure.

[FABombjoy]

Looking it all over and considering the original assembly process, I am now wondering if the large cylinder in the top of the assembly should be moved instead because turning the screw would affect both warm and cold pressures AND the downward deflection of the diaphragm during cold acceleration (not used on the Porsche WUR shown).
I believe that is what others have done, an example was detailed in this thread: http://www.bimmerforums.com/forum/showthread.php?1175959-Adjustable-WUR

I wish the UTCIS wasn't so expensive. It would be a nice alternative to drilling holes and/or banging on things with a hammer.

[Ron]

I believe that is what others have done, an example was detailed in this thread: http://www.bimmerforums.com/forum/showthread.php?1175959-Adjustable-WUR

Yep - I ran across another Porsche site where they move the upper one too.

I got a kick out of the guy in that link saying, "And NEVER plumb a wur up the way I did in that pic. It doesn't work well, just run a single line to the top port, forget that check valve nonsense." (He has the Black side of the delay valve toward the vacuum source instead of the White ;-)

+1 on UTCIS