possible WUR problem.

[boyt911sc]

Since you have confirmed that you have an ‘81 SC with lambda (OXS) and WUR-090, could you measure the heater resistance (Ohms) of the WUR when the engine is cold? Keep us posted. Thanks.

Tony

[SkiVT]

Your 090 wur should match up to an 077 FD. Tony will get you over the finish line on this one. Alsways critical to be sure all the cis parts match before too much trounleshooting.

[alk-3]

Okay will check the resistance in the AM. Along with engine number etc.
Just to help me understand the way a WUR works, if I tap down on the plug to lower the cold pressure, does that also effect the warm pressure?
I am not planning to do this unless it is determined it is nessisary, but I am trying to understand the inner workings a bit more.

[alk-3]

Just checked, the FD is 077 will have to check resistance in the morning since engine is now hot.

[boyt911sc]

Originally Posted by alk-3

Just checked, the FD is 077 will have to check resistance in the morning since engine is now hot.

With the engine cold, measure the cold control fuel pressures versus time (30 sec. intervals) no more than 5 mins. and don’t forget to measure the WUR heater resistance (do this before running the FP).

0 sec. (initial) elec. plug to WUR disconnected. This is CCP (cold control pressure).
30 sec. Connect the elec. plug to WUR and start the count.
60 sec.
90 sec.
etc.
5 mins. max. (This is WCP, warm control pressure).

Please post your data. Thanks.

Tony

[alk-3]

I think I either have a bad multimeter or a bad wur, or I'm doing something wrong.
Multimeter set to 200ohms
G to ground is reading 0.7
W to ground is reading 0.94
G to W is reading 10

I will perform the test for cold control pressure at intervals and post shortly.

[alk-3]

Okay here are the values

Cold 2.75 bar
Plugged in;
30 seconds, 3.2 bar
1:00 - 3.6 bar
1:30 - 3.6 bar and stayed there all the way up to 5 minutes

[alk-3]

I just tested the resistance again with a much better quality tester, and the values above are correct. So it looks to me like the WUR is not functioning correctly.
Any insights into those number?

[boyt911sc]

Originally Posted by alk-3

I just tested the resistance again with a much better quality tester, and the values above are correct. So it looks to me like the WUR is not functioning correctly.
Any insights into those number?

Alk,

From the above post, you seemed to me checking the TTS (thermotime switch). Why? What is the WUR heater resistance (Ohms) value of the WUR at room temp.? Your WUR is working except the CCP is out of calibration. I like to know the WUR’s heater resistance to help me understand more about its performance. Keep us posted.

Tony

[alk-3]

Okay, I think I don't know how to check the resistance than.. can you walk me through that process?
I was measuring the resistance across each terminal in the wur plug, and then the resistance to ground from each leg of that terminal.. is that not correct?
Sorry, I am new to this, and am eager to learn but may be missing some of the subtleties of these tests.

[alk-3]

Here is the Wur with the connection showing





Here is the terminal I am testing. Putting a lead onto each of these connections.




Here is the reading, and my multimeter settings.

[boyt911sc]

Originally Posted by alk-3

Here is the Wur with.................(edited)........

Here is the reading, and my multimeter settings.

Alk-3,

This is what I suspected about your WUR-090. Your current WUR will not prevent the engine from starting but will always experience erratic cold idle. There is nothing you could do to correct this nagging problem except find a good working and calibrated WUR.

I like to lend you one of my WUR’s (tested and calibrated) but you live outside USA. Shipping to Canada is not convenient and expensive plus you pay for import tax. However, if you have a US address to ship the WUR, I would be more than happy to accommodate your needs. PM me if you need help.

Tony

[alk-3]

Update;

Tony was kind enough to send me a calibrated WUR and I had a chance this evening to install it.
It made a huge difference, car started right up and ran well, but still a slight backfire when the throttle is blipped while the car is still warming up. Particularly when I blip the throttle while the rpms are dropping from a previous blip.
When the car is first started the idle is a bit low, and slowly comes up to speed over several minutes.
I decided to take the car out and get it warmed up well, when I got back I disconnected the o2 sensor and re adjusted the mixture and set the ideal.
The idle was set too fast and the mixture was a bit rich. Now it's set properly, so I'll have to wait for the car to cool down over night and then try the cold start with all the new settings.
There doesn't seem to be too much of a vacuum leak because the idle drops off when I remove the oil cap.
It's running much better, but I will post again tomorrow once I re try the cold start.