Testing the WUR; 1986 930

[spoke]

I've been observing a running issue with my 930 for some time now. About 4 years ago, I started noticing that after about 15 to 45 seconds after a cold start up (starts right up), I would hear an audible mechanical clunk from the engine area and the high idle of about 1400 RPM would drop immediately to about 800 RPM. Car ran fine. In the last year I noticed the 'clunk' was less pronounced and the RPM drop to about 800.

To eliminate the AAR, I squeezed the hose after the 'clunk' and the engine went to a very low RPM so the AAR was still open.

Another observation was that sometimes when it was hot out (>80F) the engine idle would climb sometimes almost to 2k RPM. Also noticed the high idle after a quick (10-20 minute) stop and start. Once moving the idle would drop to normal but it's weird sitting in a parking lot and the engine is idling at 1500-2000 RPM.

The oxygen sensor is not connected and has never been connected since I purchased the car in 2009.

Today I hooked up the gauge to the WUR to test pressures. The temperature is about 80F.

With the WUR connector off, I see just under 4 bar. Seems high but I'm not calibrated on good/bad measurements. When I close the valve, the system pressure looks to be just under 7 bar.

I have the sensor flap switch disconnected so when I turn the key to run the fuel pumps run. I've disconnected the spark unit but I can hear the frequency valve working. Should I be testing the WUR with the frequency valve running or off?

When I turn the fuel pumps off, the pressure stays above 3 bar for a bit of time.

[spoke]

With the WUR connector on, I saw the pressure rise to almost 4.5bar. Not sure if this is good or not. It seems high wrt some of the graphs I've seen.

[boyt911sc]

Originally Posted by spoke

With the WUR connector on, I saw the pressure rise to almost 4.5bar. Not sure if this is good or not. It seems high wrt some of the graphs I've seen.

What is the Bosch # on your WUR? Is it 0-438-140-054? Are you able to drive your car now with this WUR? Please advise. Thanks.

Tony

[spoke]

Originally Posted by boyt911sc

What is the Bosch # on your WUR? Is it 0-438-140-054? Are you able to drive your car now with this WUR? Please advise. Thanks.

Tony

Where would I find the numbers? I see 552 on the top of the WUR but not sure of other numbers. Quite limited access in this engine compartment.

I did another 'start up' with the WUR connected to 12V. The pressure started at just below 4 bar and increased linearly to about 4.8 bar. This seems high but I'm no WUR expert.

[spoke]

I see these numbers:
0438 140 153

The 153 is stamped onto the body. The rest of the numbers are cast on the body.

[Alan L]

Your system pressure (6.5 +/-)and warm pressures (3.6 +/-) are about right - slightly on the high side, but close to where they should be. Sometimes the SP is cranked up to where yours is set - depends on how the car is running on boost AFR wise.
The recirc valve makes an audible clunk - but I am not sure if it should be clunking on idle (assuming you still have the recirc valve). Posting on the 930 forum may get more answers.
Alan

[boyt911sc]

Originally Posted by Alan L

Your system pressure (6.5 +/-)and warm pressures (3.6 +/-) are about right - slightly on the high side, but close to where they should be. Sometimes the SP is cranked up to where yours is set - depends on how the car is running on boost AFR wise.
The recirc valve makes an audible clunk - but I am not sure if it should be clunking on idle (assuming you still have the recirc valve). Posting on the 930 forum may get more answers.
Alan

Alan,

The system pressure for WUR-153 is 6.7 ~7.4 bar and the WCP is 3.55~3.95 bar according to the spec. data for WUR-153. The OP is getting CCP at 3.9 bar and WCP at 4.8 bar. Both CCP & WCP are out of spec. (too high).

Tony

[Alan L]

Tony - you are right - according to my w/shop manual - for post 86 engines. Sys P 6.9-7.1
Warm pressure 3.75 +/- - but it gets confusing here because the warm up graph shows a max WP of just under 3.5 bar (without boost dump).
Altho he does not specify I took the 3.9 bar pressure to be WP - because it is close to spec as is the SP.
If it is CP, then that is a problem.
Regards
Alan
,

[boyt911sc]

Originally Posted by Alan L

Tony - you are right - according to my w/shop manual - for post 86 engines. Sys P 6.9-7.1
Warm pressure 3.75 +/- - but it gets confusing here because the warm up graph shows a max WP of just under 3.5 bar (without boost dump).
Altho he does not specify I took the 3.9 bar pressure to be WP - because it is close to spec as is the SP.
If it is CP, then that is a problem.
Regards
Alan
,

Alan,

The OP was getting 3.9 bar with the electrical connector unplugged (this means CCP) and when it is connected, the pressure gauge reads 4.8 bar ((WCP). These are the OP’s information. So both CCP and WCP are out-of-spec and the WUR needs to be re-calibrated.

Tony

[spoke]

Just ran another test this morning with the WUR plugged in. Ambient temp is just under 80F. The pressure started above 4 bar and increased to 5.3 bar in a minute or so.

Since I am basically turning on the ignition key to get the pumps running (relay set up to allow the pumps to run) the frequency valve is running. Will this affect the pressure tests if the frequency valve is running?

[spoke]

Originally Posted by Alan L

Your system pressure (6.5 +/-)and warm pressures (3.6 +/-) are about right - slightly on the high side, but close to where they should be. Sometimes the SP is cranked up to where yours is set - depends on how the car is running on boost AFR wise.
The recirc valve makes an audible clunk - but I am not sure if it should be clunking on idle (assuming you still have the recirc valve). Posting on the 930 forum may get more answers.
Alan

Alan, thanks for the info. I am attempting to move this thread to the 930 forum:

Testing the WUR; 1986 930

[Alan L]

Your cold pressure is way out of spec. It seems to be rising as it should, with power to the WUR. But the base setting is way wrong. The frequency valve won't affect this.
The WUR needs calibrating.
Alan