How To: WUR (Warm Up Regulator) CPR (Control Pressure regulator) rebuild kit

[Helirich]

The heater should not have a connection to the case. Open the cover in the WUR and you will see a wire has burned off the insulation and is touching the case. This is not a rare problem. Mine also had this problem. The wires are Teflon insulated and that insulation is very thin and wears through with vibration if it is touching the case. Move the wires from case if still intact and use some high temp silicone to hold them in place.

I took it apart. Please look at this.

5DD74149-E756-4BFE-A9EC-C1B5B9F810D1.jpg

You can see the two blue wires coming from the plug pins. The top on has two yellow wires off of it. One of them goes to a ring terminal on the bolt. That bolt goes into the case. How would that not be on purpose? Is mine wrong?

Can you verify that both of your pins are open to the case?

Edit, it appears the blue wires are just insulation over yellow wires. But it doesn’t change my ground question.

[Bitsyncmaster]

I took it apart. Please look at this.

5DD74149-E756-4BFE-A9EC-C1B5B9F810D1.jpg

You can see the two blue wires coming from the plug pins. The top on has two yellow wires off of it. One of them goes to a ring terminal on the bolt. That bolt goes into the case. How would that not be on purpose? Is mine wrong?

Can you verify that both of your pins are open to the case?

Edit, it appears the blue wires are just insulation over yellow wires. But it doesn?t change my ground question.

I just did a resistance check on mine and your correct. One pin to the case is zero ohms and the other pin is 18 ohms. I think my original WUR was not connected to the case but the wires were burned so I replace the WUR.

Since your wires look good the connector must be wired correctly.

[Bitsyncmaster]

I looked on an old computer to see if I had a photo of the burnt WUR wiring but could not find anything. I know I posted about it but that was before DMCtalk crashed and lost all the old posts. There may be other owners photos of it since I know about 3 or 4 other owners having that problem.

[nkemp]

......... One pin to the case is zero ohms and the other pin is 18 ohms.

Begs the question why they included a ground wire.

[Bitsyncmaster]

Begs the question why they included a ground wire.

All I can think of is some WUR do not case ground. I've seen photos of units without the thermal switch not ground the case. By the way, does that thermal switch reduce the heater power or increase it when hot?

[nkemp]

All I can think of is some WUR do not case ground. I've seen photos of units without the thermal switch not ground the case. By the way, does that thermal switch reduce the heater power or increase it when hot?

Might the switch turn off the heater circuit when the engine gets warm enough? FWIW, mine is grounded to the case as well.

Seems that the circuit diagram attached above could use an update to incorporate the switch and internal connection to ground.

[nkemp]

UPDATE for those contemplating doing what I've been writing about here: In short ... no happiness at all at this point

I don't drive the D much and recently it has been running REALLY CRAPPY. When I first drove it last year after refurbishing the CPR, it was OK. Not great. Better than before, but not what it should be. I figured it needed a bit of tuning. I drove it around the neighborhood a couple times this summer and it was OK, not great. Didn't run well until it was warmed up.

A couple days ago, our group did a gathering for the Back To The Future Musical in MPLS. The car ran REALLY poor until warm. Serious mosquito fogging! Nobody wanted to be behind me in the caravan. But it ran pretty good when warm. (and likely unrelated, it's not hunting this year. Rock solid idle. Go figure)

I disassembled the upper portion, checked the disk, cleaned the filter mesh (it wasn't dirty) and reinstalled. No happiness

Today I put the pressure tester on it and it reads 70PSI'ish system pressure (good) and near zero control pressure (bad). I disassembled the bottom portion (the two thin sections). Reassembled and now the WUR/CPR runs better, similar to before. Not great. About 20psi control pressure when it was 70+'ish ( didn't have my temperature sensor so it is kinda a guess ... I'd make a poor scientist). I'm not sure what changed relative to the reassembly that caused it to work better.

A couple thoughts for those interested.

I'm not sure, but the orange gasket may have shifted (rotated) over the 3/4th year it was installed. Actually, the attached disk may have rotated twisting the gasket a bit.

When you reassemble the bottom pieces, there is a large, fairly strong spring. As the spring compresses, it twists and this causes the disk and gasket to rotate, making it hard to keep it aligned during reassembly. Might the problem be that over time, this is happening inside the unit while assembled? The disk attached to the orange gasket material rotates causing the unit to malfunction? I think I saw signs of such a situation. I wish I had greased the two ends of the spring to help reduce future movement. Note that the upgrade kit instructions does not show the big spring. The spring may be unique to a subset of CPR's (WUR) including the D's. Probably the ones with two vacuum hose connections like the D's.

Now I'm contemplating what to do and I'm leaning towards the UTCIS. FrankenCIS is more interesting but less plug and play. Plus it's somewhat a hassle getting the parts. Just the block delivered is $400+.

Bosch is an engineering marvel but being primarily a pneumatic, hydraulic system, I don't think it fairs well when not used often.

I think that refurbished units are about $500 plus your old one. So the change to the UTCIS or FrankenCIS isn't that bad and you get to keep the old WUR/CPR.

That's all for now folks.

[FABombjoy]

UTCIS did not emulate vacuum enrichment when I had one. I had to install a parallel warm-up enrichment system or my car would be undrivable for the first few minutes when cold. I raised this concern with the UTCIS people but was dismissed. Eventually they offered to reprogram the unit but I had to send it in, and with no coolant temp sensor it couldn't have worked correctly anyway.

The learning curve may be higher but FrankenCIS should be light years ahead.

[nkemp]

As I dug into this, I contacted UTCIS and as it turns out, their website was out of date. The info I got from the site was an old model ... many years old. They should have it updated by now.

The current model includes warm up enrichment. Also, the new model is a single piece, no separate control box.

What I like about the older model was that it looks like I could use the FrankenCIS controls on the UTCIS block. Why do this. So that when I f-up the drivability, I could plug the UTCIS module back in and drive without frowning.

The new model does not have a pressure sensor. And I'm not sure how they do temperature, probably built into the module. The controller is integrated into the aluminum block.

[FABombjoy]

With FrankenCIS:
-Replace the thermal vacuum valve with a coolant sensor. The standard GM sensor is even the same threading.
-Plot your CPR warm-up curve and match the original. It's linear and the specs are in the service manual, so maybe 1-2 warm up cycles at most to get it correct.
-Hook up a vac source to the accompanying Megasqurt box and add MAP-based throttle enrichment to properly handle the cold warm-up enrichment.
-T-in ignition advance hose to throttle edge like Volvo

Then down the road:
-Replace the fan switch pipe with a straight pipe. Control fans from Megasquirt. One fewer leak point and easy testing of fans from software.
-Control idle from megasquirt and tune-down the oscillation. Sell the idle computer
-Control the frequency valve from megasquirt. Further reduce idle oscillation. Sell the Jetronic computer.
-Control your fuel pump from Megasquirt and sell the fuel pump relay.

A little later:
-Install electronic injectors and sell your functioning K-jet to the highest bidder.
-Bypass and dispose of fuel accumulator