WUR operation questions

[Poor-sche Lover]

So, I have my WUR taken apart pretty much completely. It's from an '82 SC. The part number is 0 438 140. I have a couple of questions. Every diagram I've seen of the inside shows only the bimetallic strip. Mine has a secondary unit that seems to be a second bimetallic strip. I have seen where this piece was discussed, but never quite explained. I see that electricity flows to the ceramic heating element, thereby flexing the main strip to move the spring. How does the second strip come into play? I see that it would break the contact between the tiny adjusting screw, but what does breaking that contact do? What is the piece to which the adjusting screw is connected? Can anyone explain the process to me like I'm a child?

My last question involves the actual valve that allows the fuel in. Mine looks like it's pretty bad. I wonder if the valve is freely moving in there? Is there a way to take the valve apart? I have removed the four small screws that hold it in, but I don't want to break anything forcing it apart. If I have to, I'll just spray carb cleaner, and hope for the best, but I'd like to clean it all the way. I hope some of this incessant ramble makes sense to someone. Let me know what you know.

Alan

[Porsche_monkey]

WUR Vacuum Question

Scroll down to the last post....

[Jim Williams]

Your WUR number is missing some digits. If you look close, you will find 3 more digits stamped into the case immediately after the 140. You should find "090".

The second bimetallic strip is wired to an additional resistance element on the big bimetal strip. This comprises a thermostat arrangement, bringing the heat up faster, and then holding it there.

Since you have the cover off the internal element, you will be seeing a very thin metal diaphragm, or maybe two of these stacked. The outside one will have an off-center hole in it. Put it back in this position when you reassemble it. Don't try to pry it (them) loose at the edge, as you may ruin it (or them). You really need an air compressor. Hold the air compressor "gun" over the input, and hold a rag or paper towel snugly up against the diaphragm. Use short light bursts of air pressure, and keep checking to see if the diaphragm has loosened up. Once they're loose, spray some carb cleaner on the parts to help get them out without bending them, and clean them when out, but again, use care. Once the diaphragms are out, use the air compressor to blow through both the inlet and outlet, and use the carb cleaner to clean out the insides of the valve. You'll find an o-ring inside. The carb cleaner may start to swell the o-ring, so if you see this, wipe the carb cleaner off pretty quickly.

[boyt911sc]

Alan,

Take a look at the picture of the WUR and '009' is the specific number for '74-'75 WUR, yours should have the '090' as mentioned by Jim Williams. HTH.


Tony

[Poor-sche Lover]

Okay, so I do have the "090". Those last three digits are stamped in, as opposed to cast in, so I didn't think it was part of the P/N. Anyway, I think I'm getting it figured out. But I have another question. Can anyone tell me EXACTLY how this car is supposed to start/idle. From what I hear, from cold, it is supposed to idle around 1500 for a few seconds before settling to 950. Is this right? Right now, it will idle at about 2000 for a minute or two, then settle down to about 1000. I'm getting closer, though. It used to not stay idling at all. Don't worry, I'll have access to a gas analyzer next week. I'm just trying to figure out the correct operation so I know what I'm hoping for. Thanks.

Alan
'82 Guards Red SC Targa

[Paulporsche]

Alan,

There doesn't seem to be any SPECIFIC figure for the idle speed and time from cold, although there probably is a spec somewhere. I've seen anywhere from 1200 to 2400 and 30 sec to 5 min. A figure of 1500 to 2000 and from 2 to 3 min seems somewhat average. This can all be adjusted. Mystery train has a thread on adjusting idle speed and time, and there are a lot on WUR adjustment.

If you want a warm idle @ 950, turn the idle speed down to this. Most likely you will find the cold idle goes down a little too. If these conditions aren't a problem for your driving and climate, I would just do that and leave it unless or until you experience further symptoms.

Remember ambient temp and barometric pressure, and type of driving from cold all have an effect on this.

[Jim Williams]

Alan,

To further add to Paul's post:

I don't think I've ever seen in print EXACTLY how the CIS cars are supposed to start and idle as far as defining the RPM transition from High to Normal. Warm idle rpm is, on the average of a range of year models for the CIS engines, 900 to 950.

For the early year models that used a manual (pun intended, the procedure is in the manual) method for engine warm up, the manual throttle control was pulled up to open the throttle plate, the engine cranked until it fired, and the throttle control adjusted to around 2400 (sounds high and I may be mis-remembering the actual number), and the control gradually lowered as the engine warmed and would accept being driven. The Cold Start Valve on these early models sprayed as long as the throttle was cracked open AND the starter was engaged. For subsequent starts with a warm engine, the throttle was not depressed at startup, and the CSV would not spray due to the microswitch on the throttle.

In '76, several elements were added to the CIS to remove the manual start-up process and allow the engine to be started without the need for the driver to depress the accelerator pedal at all, and the manual throttle control disappeared. The added elements were the Aux Air Valve and the Aux Air Regulator, which gave the engine an initial shot of air, and then maintained a gradually decreasing amount of extra air as the engine warmed.

Now to your actual question... I seem to remember a number like 1200 RPM for the cold engine revs. Maybe the number came from an owner's manual for the '76 and later cars. However I don't think that there is a number set in concrete as a specification for the higher cold idle. Perhaps such a number can be found in an owner's manual, and someone will chime in. I haven't seen a spec in the Factory Workshop Manual.

The AAR and the WUR work together to keep the RPM up and the mixture on the rich side when the engine is cold and warming. This could take from 1 to 3 or so minutes depending on the ambient temperature. As the engines get older and more worn, the CIS can't always predict how the engine will respond, and some tweaking may be in order. A different (from Stock) AAR might be required to place the cold idle where it was when the engine was new.

Just some observations which might help...