1980 ROW 3.0 CIS Diagnostic Help

[Silver-911]

Hello everyone! I was hoping I could get a bit of help with making sure my CIS is set up correctly. I had the car at my Porsche mechanic last year to get the WUR rebuilt and he did a few other maintenance items (adjusted valves, oil service, new plugs etc). He also confirmed WUR pressures were correct but the car left not being 100%. He found a few of the injectors to be leaky/poor spray pattern and also commented on the magnecore wires and suggested replacing them. I got the car back with a higher than I would like idle as well, and he mentioned that he did that because it being better than having it too low as he couldn't quite get the car to settle in a happy spot, sometimes it would idle way too low, other times too high. But the idle never hunted, and stayed around 1100 rpm for me, sometimes dipping to 1000ish. More on this later...

I drove the car last summer and into the fall, the car seemed to run OK but had intermittent rough running above 4k, which I chocked up to the leaky injectors and planned to replace them this season.

Being in Canada the car sat for a few months over the winter, but I was fortunate enough to pull the car out of an early slumber and get a few drives in during January and February. As the temps were quite cold I let the car warm up for quite some time and the roads were still kind of bad I didn't push the car at all.

After the first warm day with somewhat spirited driving the car was running great. On my way back it decided to start running awefully above 3k, and more than 10-15% throttle. I could barely make it up a hill. I had just filled the car back up and I assumed I picked up some bad gas. A few tanks of gas, new fuel filter and some fuel system cleaner later, I didn't notice much improvements. I tried to get it back to my mechanic but his shop is closed until April as he is moving.

I decided to order some new injectors and spark plug wires as recommended, and am currently waiting for them to arrive, as well as a CIS pressure tester kit. However, while I am waiting I decided to check the timing as I have a good digital timing light that lets me set the advance. I checked it and it was way off. And as soon as I pulled the vacuum lines to complete the check it would hardly idle. I put the vacuum line sback on the distributor and checked the idle, it was currently sitting at 5 degrees advance, WITH the vacuum lines connected. Almost like the car was timed with the lines connected. I disconnected the lines again and timed the car at idle to 5 degrees and then double checked at 4000-6000rpm and the mechanical advance was working and hitting a fairly consistent 21 degrees advance. I buttoned it back up and took it for a drive.

What a difference. The car pulls harder through the mid range than it ever has. However, I still get intermittent missing/stumble above 4,000rpm and a feeling of lack of power. I am wondering if the leaky fuel injectors could be causing this, as I understand it they dump too much liquid fuel into the runners instead of misting it in as it should and when called upon with a heavy load you get an overly rich mixture as the extra fuel gets sucked into the cylinders. Please correct me if I'm wrong in this thinking. Also, the idle has now settled to a nice happy 950 and is consistent with no missing or hesitation while running.

This has lead me to second guess how the car is currently put together. I pulled the numbers for the WUR (0 438 140 089) and the Fuel Distributor (0 438 100 031) and it appears to be correct for a 1980 ROW car. (body is a US 1976 911s with euro 930 bodywork). But the engine is a 1980 911SC powertrain.

However, it appears to be missing a few components, specifically the decel valve and the thermo time valve. Currently the vacuum system is connected like this:

Upper vacuum on back of throttle body (facing front of car) goes to the lower port on the distributor. Lower vacuum on the back of the throttle bod is going directly to the vacuum port on the WUR. The front vacuum port of the throttle body is going to the upper port on the distributor.

The car seems to start and idle fine while cold, with idle climbing from initial 800-850 to about 1100 until warm where it now settles down to a nice 950 after I corrected the timing.

I know I don't have a lot of info to go on for you guys, as I am waiting for my pressure testor to confirm the WUR functionality and control pressure. However I did confirm their is voltage to both the WUR and the other air valve on the right hand side of the engine. The car does run a bit lumpy when cold though, so the thermo time valve before the WUR would probably fix that. I could try pulling the vacuum line off the WUR while the car warms up and see if it runs smoother until it warms up.

Also, I do have an innovate wideband 02 sensor to install next week which will allow me to confirm the fuel mixture and see what the car is doing while it is running.

I know this is kind of a long and rambling post, so I apologize. I guess what I'm really looking for is some guidance with my current system, what components should I track down and introduce back in, or can I make it function sufficiently with what is currently here.

Also of note, leakdown test was good, the engine is in good mechanical condition with a recent rebuild (probably less than 20,000 miles ago), and valves currently adjusted less than 5,000mi ago.

[Glenfield]

Silver, it’s really hard to unpack the problem given description. I’m not the one to help you but there are some CIS gurus here who will have the car purring in a jiffy.

I reckon you should bullet out your problems and what you’ve changed. When you get the CIS gauges you’ll be able to do the rest.

They should carve the below thread into stone and put it on top of a hill. Porsche owners will worship these men like gods for centuries to come

CIS Troubleshooting for Dummies

[2aircooled]

Hi Silver-911,

Sounds like you have a really nice car, making some suggestions for you to start with, others will chime in soon...

Originally Posted by Silver-911

But the engine is a 1980 911SC powertrain.

As a starting point, it might be a good idea to check the engine type stamped on the engine (for example 930/09), the location can be seen in this post 911 sc engine. The engine type number can help indicate if the engine is originally ROW or USA specification...
You can find out more info here: Simon's Porsche 911 SC Site

Originally Posted by Silver-911

However, it appears to be missing a few components, specifically the decel valve and the thermo time valve.

Depending on what your engine type is, one option is to look through either the ROW or USA PET to see what components may be missing.
If you haven't got the PET yet, you can download the ROW PET from here:
https://www.porsche.com/international/accessoriesandservice/classic/genuineparts/originalpartscatalogue/
and the USA one from here:
https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/originalpartscatalogue/

Originally Posted by Silver-911

Currently the vacuum system is connected like this:

Upper vacuum on back of throttle body (facing front of car) goes to the lower port on the distributor. The front vacuum port of the throttle body is going to the upper port on the distributor.

It sounds like you have a 911SC distributor with two vacuum unit ports installed in your car, it is used on engine types 930.07/08/16/17 according to the USA_911_78-83 PET.
It is my understanding that the vacuum unit on distributors for 911SC ROW engines only have one port for vacuum advance... There may be exceptions of course, so others can correct me if I am wrong... The distributor for the 81' 930/10 engine in my car has one port for vacuum advance.

Originally Posted by Silver-911

The car does run a bit lumpy when cold though, so the thermo time valve before the WUR would probably fix that. I could try pulling the vacuum line off the WUR while the car warms up and see if it runs smoother until it warms up.

Pulling the vacuum line off the 089 WUR (temporarily to test only) should lower the control pressure and change the AFR (assuming that the 089 WUR is functioning correctly), whether it smooths out the engine or not depends on how the mixture is set.


Posting some pictures of the engine bay and the CIS will also help....

[SkiVT]

Lots of help on this link. Check the vacuum line routing in this picture. You should also have most of these components. As mentioned by others, posting pictures of your engine bay CIS parts never hurts.

https://jimsbasementworkshop.com/CIS/pages/air_vaclines.html

[Silver-911]

Thanks for all the assistance so far guys. I know it was kind of a long winded post. I will try to consolidate the info a little better next time.

The engine number is 930/07, we were led to believe from the previous owner of the car (my father purchased the car in 2006, he passed away last year and left the car to me), so I can't confirm this, but I believe the car has 964 cams and the engine was recently rebuilt. No idea what other internal modifications were done, but when the Porsche specialist was working on it last year he did comment that it appeared to be put together well as he noticed a few things he regularly does when doing a rebuild, so someone knew what they were doing.

The main issue is a hesitation/miss/lack of power at higher RPM with mid/high throttle input which smooths out a bit under WOT or low throttle input. It feels like the timing is off under these conditions or the engine is starved for fuel or too rich. Just kind of falls flat on it's face and bogs down.

The distributor has two vacuum lines on it.

Hopefully my fuel pressure test kit will arrive this week. I also should have the wideband O2 up and running by the end of the week to double check if it's running lean or rich.

[Silver-911]

Originally Posted by 2aircooled

It sounds like you have a 911SC distributor with two vacuum unit ports installed in your car, it is used on engine types 930.07/08/16/17 according to the USA_911_78-83 PET.
It is my understanding that the vacuum unit on distributors for 911SC ROW engines only have one port for vacuum advance... There may be exceptions of course, so others can correct me if I am wrong... The distributor for the 81' 930/10 engine in my car has one port for vacuum advance.


Pulling the vacuum line off the 089 WUR (temporarily to test only) should lower the control pressure and change the AFR (assuming that the 089 WUR is functioning correctly), whether it smooths out the engine or not depends on how the mixture is set.

I was thinking of doing this, however I was afraid I'd send the mixture to lean and perhaps cause harm to the engine. I suppose I could do it as a quick test just to see if I get some more smoothness under the conditions that cause the rough running. I will attempt this later today and report back.

[Silver-911]

So I pulled the vacuum line from the WUR and did some quick pulls and it seemed to help smooth out the top end performance, so gut instinct is telling me it's running a tad lean under load at the top end.

Definitely need to get the wideband O2 sensor installed and get fuel pressure tester on it to see what's going on.

Pulling the vac line off the WUR did introduce a vacuum leak and increased the idle to about 1,100 from 950, so for future testing I'll be sure to plug the vacuum port.

Can I get away with deleting that vacuum connection from the WUR, so long as when I test it the control and system pressures are OK and I can properly set an idle fuel mixture?

[Silver-911]

Well.. I think this got a bit more confusing for me. It appears the car also has a lambda control box under the passenger seat? I can also see an electrical connection at the back of the fuel distributor area/near the throttle plate. Could this mean the car is also controlling enrichment using the lambda computer, which could also be why the car starts fine when cold without the enrichment mode of the vacuum WUR.

[boyt911sc]

Silver,

Could you post some pictures of your motor? You seemed to have ROW and US spec CIS components on your engine. The last mechanic who worked on your car could be a good and honest one but was not familiar with CIS. He should have told you about this problem because this engine will not run well with the current set-up.

Find a mechanic who is very familiar with CIS to get this problem corrected. Keep us posted.

Tony

[Silver-911]

Originally Posted by boyt911sc

Silver,

Could you post some pictures of your motor? You seemed to have ROW and US spec CIS components on your engine. The last mechanic who worked on your car could be a good and honest one but was not familiar with CIS. He should have told you about this problem because this engine will not run well with the current set-up.

Find a mechanic who is very familiar with CIS to get this problem corrected. Keep us posted.

Tony

I will post some photos tomorrow when I have some good lighting. Anything in particular I should get closeups of?

The mechanic the car was last at is a Porsche specific specialist that has been working on these cars since 1979. They build race cars and do full restorations. Including a 906. I'm surprised he didn't get into the system not being compatible. Unless he assumed the components were correct for the 1980 930/07 engine and didn't run the numbers...

[pmax]

Fuel distributor has a plate in front.
WUR model last three digits.
The components "at the back" where the FV is.
The saucer shaped valves and AAR on the right.
Lambda controller #

[boyt911sc]

Originally Posted by Silver-911

I will post some photos tomorrow when I have some good lighting. Anything in particular I should get closeups of?

The mechanic the car was last at is a Porsche specific specialist that has been working on these cars since 1979. They build race cars and do full restorations. Including a 906. I'm surprised he didn't get into the system not being compatible. Unless he assumed the components were correct for the 1980 930/07 engine and didn't run the numbers...

Silver,

Please take some close up pictures of the following:

• Ignition distributor showing the Bosch ID #.
• Fuel distributor showing the ID #.
• Warm-up Regulator.
• Intake runners showing the -2R or -4R.
• Backside of the throttle body.
• Air flow metering unit with ID #.
• Auxiliary Air Regulator on Intake runner #5.
• Engine block showing the engine type.

These informations would be more than sufficient to identify the problem about your engine. Based from your initial feedback, I would say you would need to replace the fuel distributor and warm-up regulator. FD-077 and WUR-072 to replace FD-031 and WUR-089. Keep us posted.

Tony

[Silver-911]

Here is a shot of the engine overall. I've removed the hot air hose to the blower motor for access to spark plugs and fuel injectors. I blocked off the fan outlet to help maintain pressure over the cooling fins.

• Ignition distributor showing the Bosch ID #.
  
  
• Fuel distributor showing the ID #.
  
• Warm-up Regulator.
  
• Intake runners showing the -2R or -4R.
  I'm not sure where to photograph for these numbers, please advise.
• Backside of the throttle body.
  
  
  
  
• Air flow metering unit with ID #. - Unable to see where this is.
• Auxiliary Air Regulator on Intake runner #5. - Next Post
• Engine block showing the engine type.
  

[Silver-911]

Here is a photo of the right side of the engine bay.



Here is the back side of the fuel distributor... doesn't look right to me...


Here is the box under the passenger seat. The car does not have an O2 sensor installed.

[Silver-911]

Here is a better shot of the WUR, more clearly showing the last 3 digits.

[Silver-911]

I managed to get a photo of the intake runner.

They appear to be a -2R

[SkiVT]

The path of the fuel lines and vacuum line off the wur would help. So removing the fan and big air hoses temporarily and getting another picture of that area I think would help. You might consider rethinking blocking the main air outlet. Air cooled engine has the main fan moving air across the fins and away to remove heat. There is no pressure like exists in the tailpipe path.

[Silver-911]

Originally Posted by SkiVT

The path of the fuel lines and vacuum line off the wur would help. So removing the fan and big air hoses temporarily and getting another picture of that area I think would help. You might consider rethinking blocking the main air outlet. Air cooled engine has the main fan moving air across the fins and away to remove heat. There is no pressure like exists in the tailpipe path.

I removed the two hot air hoses to get a better view, I can remove the fan if needed.

Here is a video of the routing of the lines connected to the WUR

https://photos.app.goo.gl/bDJ8VKHZLWyxG1oj6

As for blocking the port on the left, I assumed as that is normally connected to the heater circuit for hot air flow it has a bit of resistance allowing with the rest of the air blowing over and down over the cylinder heads. I blocked it as there is nothing connected right now, this was only temporary until I reconnected everything. Either way, back on topic haha.

[SkiVT]

The video helps. The air duct is just a temporary diversion as you mention. Your wur is mounted opposite of others as the vacuum line typically points away from the engine. Not a problem, just looked different without the line visible. You have an interesting mix of components that is well above my head to sort out. It looks like you have both vacuum assisted components and a lambda trying to control fuel mixture. Usually the two don’t play well together. I would wait for Tony to chime in....

[boyt911sc]

Silver,

I like to see the engine driver side area particularly the AAV and decel valve. Make it two, also the rear side view of the CIS boot mounted between the throttle body and the metering unit. People sometimes refer it as “Pope’s hat”. There are two vacuum hose connections to this boot and like to confirm it. Thanks.

Tony