"Six months clean" Ha - that is cute.

Is it a 12 step program?

There really is no argument, as long as we use the same terms. I'll use "plug" to mean the small diameter round pin used to adjust the bimetallic arm and cold pressure, and use "disc" to refer to the cylinder holding the inlet/outlet ports as well as the diaphragm and adjusts the warm pressure.

One of the misconceptions is that the bimetallic arm raises and lowers the small pin that moves the diaphragm within the cylinder, thus altering fuel pressure--it does not!. The pin which pushes on the diaphragm is moved by the spring which is underneath it (see the diagram.) The function of the bimetallic arm is to compress the spring when the engine is cold, which moves the pin downward, which lowers the diaphragm, which lowers pressure.

When the WUR is fully warmed and the bimetallic arm is fully bent upward, it removes tension from the spring and the pin pressing on the diaphragm is governed only by the spring. When you adjust warm control pressure, it is imperative that the WUR is fully warmed and there is no bimetallic arm tension on the spring, thus knocking the "disc" down will push the diaphragm against the pin and raise pressure (same effect as pushing the pin upward.) This is why, when installing a new WUR, you should adjust the warm control pressure first--to ensure that the pin pushing on the diaphragm is not being influenced by the bimetallic arm.

Now, when the WUR is cold, the bimetallic arm is compressing the spring, lowering the pin and controlling the cold pressure. Knocking the "plug" down will move the arm downward, further compressing the spring and further lowering the pressure. Moving the plug up allows the compressed spring to "uncompress", raise the pin, and raise the cold control pressure.

Understand that the distances the pin moves the diaphragm is very small and it's easy to over adjust the plug for cold pressure. If the above makes sense to you, then you will see that warm control pressure stands alone from the bimetallic arm, if the WUR has been set up correctly. If there is still tension on the spring controlling the pin caused by the bimetallic arm, then yes, "knocking the plug" will influence warm pressure.

Bob,

I'll try to explain it but I may come out not too clear so feel free to contradict or offer your thought. A discussion is what we all need and I would also learn from other ideas. Based from my limited tests and observation how these WUR work:

When the bi-metallic spring has been fully heated and completely deflected (applying zero or minimal resistance) to the coil spring, this is the WARM control pressure. So final adjustment is done when bi-metallic spring is disengaged or off the spring. In short, you don't need the bi-metallic spring to set the WARM control pressure. It is all between the coil spring and height location of the disc that determines what value for the WCP.

When you change the height/depth of the plug/pin what it does is alter the initial resistance (down force) of the bi-metallic (unheated) against the spring. This is the cold control pressure. Note: The location of the disc is still the same and unchanged. Now turn on the heater and the bi-metallic spring will slowly and gradually deflect off the spring. You could verify this process by observing the fuel gauge.

How do you know that bi-metallic does not affect the WCP? Remove the bi-metallic spring and repeat the test. Please feel free to commend and would like to hear your ideas. Thanks.

Tony

Both explanations make perfect sense. What you guys have done is removed the mental block of the "common misconception" regarding the purpose of the bi-metallic arm. Once the arm has "played out" it is dead as to function.

Essentially, full warm control pressure IS control pressure without influence from other variables. Take the variables away and WCP is constant.

When the temperature variable changes - specifically temperature on the pressure graph - what is impacted by the temperature to make WCP change?

Thanks a bunch. This is an epic change in mind set.

Thanks Bob for the page from the factory manual. It's a little late here for my brain to process all the numbers, but I'll look more closely at it tomorrow. But you're right about the version of the WUR - the Euro seems to have kept a number of earlier parts, like the fuel filter too.

I had the same misconception about the metallic arm - that it actually lifts up the diaphragm. So in other words, the warm control pressure is defined by the spring, the rod, diaphragm, and the location of the dark disc that holds the fuel lines. And that's it. The bimetallic arm just intervenes to lower the pressure by holding the spring down when the engine's cold, so you get a richer mixture. Once it's warmed up, the arm completely releases the spring and has no more effect (when it's working properly). Which is why the cold pressure adjustment does not affect the warm pressure adjustment. Guess that answers the question!

I'd just note that my WUR is not adjustable - it's the one pictured with the yellow circle around the plug. so I'll have to open it up if I want to move things upwards.

I was able to do the pressure measurements today, but I didn't have time to try 'knocking the plug'. I recorded control pressure at 15 second intervals from the moment of startup. I even made a little graph on Google Docs. gotta love it. long story short, the pressure started out at 2 bar, took less than two minutes to rise up to around 3.2, wavered upwards a little bit to 3.0 (the graph probably exaggerates the variation there at the top of the curve), then settled in just above the 3.2 marker on the gauge and stayed there from about six minutes on. I'm calling that 3.22

Here's the graph. The car was not dead cold, as in left overnight. I had to drive it for 3 or 4 minutes today, and then let it sit for 5 hours before doing the test.

http://forums.pelicanparts.com/uploa...1317454208.jpg

oops - that's pressure in bar on the vertical axis and time in minutes along the bottom.

With all the discussion about the functioning of the WUR, let's not lose sight of your problem. From your original post, you have a cold start/running problem (in addition to a possibly overly rich mixture) therefore, it is critical that you measure your cold pressure accurately and compare it to the chart for your WUR. Your last posts (see highlighted comment) indicates a cold pressure of 2 bar but you didn't post the ambient temperature so we (and you) cannot conclude if it's too high or too low. Currrently, you have symptoms of too high cold control pressure so there's no need to open up the WUR--"knocking the plug" will suffice.

My suggestion: Get your WUR into spec by setting warm and cold control pressure. If after all this you still have a problem with cold starts/running, go back to the air leaks possibility--you'd be surprised at the odd places they can be, including any hose or fitting between the front firewall and engine. Then, get the car on a gas analyzer and have the mixture screw accurately set since it has been tweaked.

That sounds like a good plan. The rough running goes on for far longer than the time it takes for the WUR to get up to pressure, so I'd guess there's something else going too - maybe a stubborn leak. Stands to reason that in a 32 yr old car there would be more than one thing going wrong at a time.

The range of different pressure numbers is still a bit confusing. Acc to the factory sheet Bob posted my warm pressure actually seems to be within spec, and maybe the cold too. And I'm not sure why I've got one cold reading of 1.65 and another of 2.0 (with the engine running). I'll do the tests again with more attention to the temperature.

The key to success (and to avoid hair-pulling frustration) in dealing with CIS issues is to eliminate one variable at a time. In your case, eliminating the WUR as a cause is the most logical since you've already spent some time on it and it may even be in spec and, thus, eliminated. I think you are on the right track. Good luck and post your results.

The CCP range at a given temperature is the acceptable range of operation.

The graph bar which shows increasing pressure with ambient temperature increases is because the bimetallic arm bends with outside temperature changes while the car is shut off. You need to know the outside temp - or temp in your garage - and log the cold pressure at first start up - and compare that number against the graph. Once running, even with the 12 volt heating element disconnected, the engine heat will bend the arm until WCP is reached. Unless I am mistaken, the graph is for first cold start up only.

New Data
 

I redid the tests today, with the car good and cold after sitting overnight. And, I had a friend start the car while I was watching the pressure gauge. interesting results.

1. Cold pressure started out at 1.5, in ambient temperature of 18C. That is much closer to the original reading I got while running the fuel pump with the WUR unplugged (1.65), but also low. A couple days ago I reported having a reading of 2.0 bar just as the car started. I think that reading was affected by the car having been driven for a few minutes earlier in the day, and the day itself being warmer. Also I wasn't looking at the gauge right as the car started. So this should be a more accurate reading.

2. Warm Control pressure 3.3 at 90C. After startup the pressure settled in at just above 3.2, as it did before. However it was not up to full operating temp. So I took the car for a drive on the highway, went to Sears to pick up a ball peen hammer to adjust the WUR, and then checked the pressure again. Now it had moved up to 3.3. Much closer to spec. I checked it a number of times as I drove around and it stayed stuck on 3.3.

Drove back home and went to work on the WUR, and found that the pressure had dropped again, just slightly, to about 3.25. I tapped on the disc, nothing happened, gave it a few good whacks, and it obligingly jumped up to 3.4 exactly. Drove it around again, checked, and again it dropped. So I tapped it up again, and it went slightly over this time, maybe to 3.45. Given the variation, I'm happy with it as is and decided to leave it alone before I made it worse. Drove the car again, and have to say it seems a lot happier. Could be my imagination but I think its an improvement. I'll have to see how it behaves when I start it up cold again in the morning.


SO: is there anything that can cause this kind of fluctuation in the Warm Pressure well after the car has started up? Is it possible that the WUR is dirty or corroded inside? Or is something else in the fuel system causing the problem? or, is the warm pressure changing in response to the engine temperature finally getting up to 90C? (that seems to take around 20 minutes, depending on how I drive). Just throwing out some ideas....

Bob - I was referring to the conflicting numbers I had gotten in my tests, and different assessments in the thread about what was high, low, or ok. It was getting a little confusing (no sour grapes or anything there - this thread has been unbelievably informative and helpful).

FWIW, the numbers I'm using above are from the factory manual page you posted, and also the CIS Primer website I mentioned before.

WUR specs2

So for cold pressure at 18C, 1.5 looks low, according to the graph (same with the earlier reading of 1.65). The factory manual page states 3.2 to 3.6 as the acceptable range for warm pressure. the web page above lists 3.4 with vac connected. So I'm taking 3.4 as the right number, given that the engine seems to be running rich anyway.

Thanks again for all the input!

IMO, your warm control pressure is o.k. and if it were me, I wouldn't mess with it anymore. Slight fluctuations could be from a loss of vacuum at idle, and it is so minor I wouldn't be concerned.

As to the cold control pressure, yes, it is low--low enough to possibly cause a hunting idle (too rich due to too low of pressure) situation if everything else in the CIS was up to spec. Instead, you have cold start problems which resemble overly lean conditions when by all rights you should have overly rich symptoms. This is what makes me think you either have an air leak or the mixture screw was turned to lean out the mix to compensate for the too low pressures. Then, again, you report the car running too rich (black deposits, poor mileage) which could be from turning the mixture screw to enrich the mix--compensating for an air leak. With such low cold pressure and still having lean cold running symptoms, my money would be on a yet to be discovered air leak.

I would be interested in knowing how your car starts and runs under cold conditions tomorrow.

Here is a pic of the inside of the WUR. It is a pretty stout unit. The o-ring type seal is re-useable. It may even be part of the base - I can't remember.

Time to get in there and whack on the little plug.

http://forums.pelicanparts.com/uploa...1317604487.jpg

Great shot of the WUR guts! One thing I found helpful in raising the plug was to use a large C-clamp on the base of the plug (the bolt in the picture) and press the plug upward. Went nice and smooth.

Wur......
 

Danny,

Leave the WUR alone at the moment. It is working and should not be causing you any problem. The spec is a guide for fine tuning. I would suggest that you focus your effort on two (2) things:
(1). Unmetered air (vacuum/air leak) going into the system. Pressurized the system. It is either leaking or not!!!!!
(2). After you have verified and confirmed that the system has no significant air leak, have the exhaust gas analyzed using a gas analyzer and re-set the mixture as needed.

The Bosch WUR (0-438-140-xxx) is an old and antiquated apparatus but it works. Some people believe this is a precision device which I disagree totally. An instrument or device that has a 20% variance could not be considered a precision instrument. See chart for -045 WUR. At 10°C, cold control pressure is 1.6 to 2.05 bar. With a mean of 1.8 bar, it has 10%(+/-) spec range. In short, you have other problem/s to consider before blaming the WUR.

Tony

Well, I took off the CIS gauge today and started up the car and... no change. If anything it's a little crankier than it was, for the first ten minutes or so. that may be due to the higher warm pressure now that I adjusted the WUR. As usual, it runs fine once it's up to temperature, maybe a little better now than before.

So the vacuum leak angle is making a lot of sense to me at this point. I've gone over the engine with an unlit propane torch and didn't find any leaks, but I'd like to get more scientific about it. Is there a way to pressurize the system without having to purchase expensive machinery? All ears...

Contact Scott.K...........
 

Danny,

There is another member working hard to make his CIS engine run and recently done a pressure test. This method is very simple and works better in locating hard to find vacuum/air leaks. He did a pretty nice job for pressuring the unit. Try to contact him.

Tony

Thanks a lot Tony, I'll do that. And thank you Bob, Ossiblue and Tony for all the input! I was hoping someone could stop me from pulling the trigger on replacing the WUR. Now I know how to adjust the thing myself, and that it's probably not the culprit anyway. All very valuable information.

plan of attack (in this order):
1. vacuum leaks
2. fuel mixture adjustments
3. get inside the WUR and bring the cold pressure back up to the right value.

I'll update when I have more info.

I had forgotten about this but in March I had a bad backfire that blew the injector out of the #1 cylinder and unseated the air box, and left me stranded in a parking lot. I had it towed to a mechanic who replaced the pop off valve, which was blown out of its socket, and refitted the air box. It may be that that's where the vacuum is compromised. I did check the injectors for leaks with the propane, but didn't find any evidence.

Sit down and relax.........
 

areaman,

Your plan of attack could be compromised if the test or procedure that you have chosen is not effective. Not being able to locate any source of vacuum/air leak does not mean you don't have any. Particularly, if you are using starting fluid, or carb cleaner, or unlit propane for your search. Some people get lucky and locate the culprit/s when they use these methods. But you cannot rely on luck all the time. How lucky do you think you are today?

Smoke machine or pressurized air will do the trick. It would take less than a minute to do the test (investigation) after you have injected low supply of compressed air. It does not require expensive tools or apparatus to do this pressure test. Use your imagination and creativity to get this simple test done. Perform one test at a time and avoid guesswork.

In case you need help to test your air-box for air leak, PM me and will forward procedures with pictures how to do it.

Tony