video
 

I was not able to test fuel pressures but did shoot a video of the start and cold running. A friend who owns a smog shop noted as we chatted that the timing was way off and there was white smoke after warm on had acceleration. He noted he could smell fuel but no leaks were found.
Here is the link
Mikes 81 sc cold running - YouTube

Your fuel pressure measurements will help a lot in guiding you to your next step. Your goal for the car (in bold) should be to get the car to start and idle perfectly when cold, as there is no reason why it shouldn't. As Tony has posted, your current wur is not designed for you CIS and could be the entire problem. The cold start/backfiring issue is very typical for a wur that is producing too high of cold control pressure--your test results will confirm if that is so--but that can be adjusted. Your lack of power when accelerating can also be attributed to the wrong wur. The one specified for your car allows the wur to drop fuel pressure (thus making the fuel mixture richer) under wide open throttle via a vacuum port. If the wur you now have does not have that port, or if you have the vacuum line connected to the wrong port, you will be trying to accelerate with an overly lean mixture and have a feeling of no power. Tony knows the proper wur for your car as well as the correct connections for the vacuum and ambient air ports. I believe he also knows if the wur you now have has the proper enrichment ports for your car.

All this being said, the wur may not be the problem, though you have apparently eliminated ignition problems. You still have a strong fuel smell coming from the running engine which is not normal and may be from improper ignition or an internal fuel leak. However, getting the proper fuel pressures and proper functioning of the wur will be essential to a perfectly running CIS which, IMO, you should be striving for.

All of the above........
 

Mike,

You have been advised and I couldn't have said it much better and clearer than what LJ mentioned. The only thing I could add aside from checking your ignition setting is to test and confirm for any source of unmetered air (air or vac leak). Keep us posted.

Tony

Thanks
 

Thanks Tony and LJ. I am not going to post anything else until the fuel pressure is tested an I have numbers. I am going to follow the steps you have asked me to follow and do this properly.

Mike,

If it were my car, I would first find the correct WUR and replace it. The -011 WUR on your car now has much lower cold control pressures than the correct one. The warm pressures are the same. SO, this could be one reason why the car runs poorly when cold but acceptably when warm.

The 1981 models introduced a separate control unit for acceleration enrichment. It's a somewhat complicated system to describe, as it does different things at different temperatures, throttle positions, etc. It's well described in the Service Training booklet for the 911 of that year. Any competent shop should have a copy of it.

If the car were mine, I'd have a shop change the WUR, check the pressures and look for any leaks, then make sure that the O2 sensor and the enrichment systems are operating properly.

You also mentioned that the car ran worse after changing the plugs and wires. I don't know what wire you used but I've seen people have problems with some of the aftermarket wires. I only use the OEM plugs and wires.

Good luck,
JR

Get the correct WUR from Tony, then get the rest correct.

Check to make sure I have all set up properly for test
 

I have been a little delayed as a result of a family illness. I wanted to make I had all correct and am understanding the fuel pressure test. From what I have searched on the forums
The fuel line from the fuel distributor to the WUR goes to the gauge.
The line from the gauge with the valve goes to the WUR
Remove fuel pump relay and jumper 87a and 30
I have also heard you can disconnect the coupler to the mixture meter to do the same thing? It allows the fuel pump to run?
Disconnect electrical connection to WUR
Turn key to on and read pressure with valve open to get cold control pressure.
Close valve to get second reading, system pressure
As per Tony, test OHMs at WUR.
Report all back
This is all new to me and want to make sure I have all correct so its done properly

I think that's right. I'll be doing this sometime in the next two weeks also, though I think my gauge is defective.

You've got it correct. The statement in bold is the electrical connection to the air flow sensor. If you unplug the connection, it breaks the ground connection to the fuel pump relay (terminal 85) leaving the relay in a "default mode" where power from 30 goes to terminal 87a--it serves the same job as jumping the two relay terminals.

Thanks
 

Thanks for the confirmation and clarification. I will get that done this morning.

Numbers finally
 

After a family illness I was able to finally get back on this project. Here are the numbers I got
Ohms at WUR
25 ohms
Temperature at time of test 62 degrees
System pressure
4.7 bar
Cold control pressure
1.0 bar
Warm control pressure
2.5bar
Ran compression as we'll. Included as a side note
Compression
1
152
2
152
3
155
4
160
5
160
6
158

Your control pressures are way low. My advice... replace the WUR with the correct one for your car. I don't have a spec book handy for an 81 but your system pressure may be on the low side of spec as well.

JR

Looks like your warm control pressure is about 1bar too low, leading to an overly rich mixture. Add to this a further lowering of pressure under wide open throttle, and that may be part of the problem. Regardless, you need to get the warm pressure in spec to eliminate it as a suspect.

Note that I'm basing the warm pressure on memory, and I don't know the specs for a 011 wur. You should confirm the pressure from Tony or someone who has a reference.

I wouldn't try to get the pressures correct for a -011 WUR, because the rest of the system is expecting the pressures it was designed for. Correct pressures for an -011 may be too low for the fuel head, airflow sensor, etc. I don't keep spec books any more for cars I don't own, so I don't know what is correct for an -011 off of the top of my head. What Porsche specified for the 930/16 engine in an 81 US SC was 2-2.4 cold, 3.4-3.8 warm. At your test temp of 62F, you'd be looking for 1.8-2.25. Control time was reduced from the previous 2.5 minutes to 2.

JR

New year, new approach.......
 

Mike,

I got your email today and sorry to hear about the illness. Anyway, it has been awhile since I read this post and wondering what has happened. Last month, I offered you a FREE WUR loaner to use for your troubleshooting and you declined. I was not selling it but lending it to you so you at least try it and see if the problem is your current WUR. There is nothing to lose except spending for the postage for shipping the WUR to you and back.
http://forums.pelicanparts.com/uploa...1389551270.jpg
These are WUR's from some PP members undergoing testing and calibration in my basement. The winter is very cold and keeps me busy during this time of the year. My offer to you is still available and decide soon. Insisting in making the WUR-011 to work is commendable but not a smart move. If I remember correctly, you obtained this car for almost free and you were lucky. But you can not depend on luck all the time specially for diagnosing and troubleshooting.

Tony

Your offer
 

Hi Tony. I will take you up on your offer. I wasn't declining. Got very distracted and had to put all on hold. Thanks for the help. I will call to arrange all. Looking forward to figuring this out.