Your engine number (07) indicates a 1980 US SC. That model had an oxygen sensor and the "mini-brain" in the silver box you show under the passenger seat. The sensor and electronics controlled a frequency valve, which adjusted the differential fuel pressure in the fuel distributor. The return line from the WUR was plumbed differently - I believe it T'd directly into the return line from the FD pressure regulator. And I think this was a "no vacuum to the WUR" system. And the throttle body had the two vacuum lines for the distributor.

The Euro had a vacuum controlled WUR, with a variety of ancillary parts to go along with it. The line connected to the open port you see on your WUR. In the US WURs, that port is connected to the throttle body also, but above the throttle plate, so it isn't a vacuum line, it is an atmospheric pressure source of filtered air. You don't have that connected, though that ought not, short run, make any difference (other than the question of is the throttle body port closed off - without being connected to the WUR that port is a source of unmetered air.
Euro SCs had no O2 sensor and none of this electronic stuff. Different FDs and WURs. Had vacuum to the WUR? Only one vacuum line to the distributor?

But the most important difference between US and Euro SCs of this era is compression ratio and intake port and runner size. The Euro ports and runners are the same larger size as the 78-79 SCs world wide. 39mm intake ports. The '80-83 US SCs have 35mm intake ports, with narrower runners. They also have 9.3:1 CR, while the Euros of that era have 8.6 ('80) or 9.8 (81-3).

A trained eye can spot the difference between the larger and smaller intake runners - but I can only tell when comparing a known engine to the one under consideration. You could pull an intake runner and just measure the ID of the port.

The pistons, with their different CRs, are interchangeable.

The ignition timing on both ROW and US '80s is with vacuum disconnected, and is the same - 5* BTDC. The 6,000 RPM range is a bit different, but the +/- overlap, so that can't be critical. However, the US and ROW distributors are different - both the distributor itself, and the vacuum advance/retard. If the ROWs had only one vacuum line, yours is a US distributor.

At a guess, someone removed the frequency valve and disconnected/disabled the mini-brain, and that odd looking fitting on the backside of the FD may be part of this. All of this is going to take a bit more work tuning things than if you had a standard US or ROW '80.

Looks like your engine has been altered. Tony has the CIS part numbers memorized, so you should be getting a better handle on things.

You are going to end up knowing more than you might care to about how to get this engine running well, and you may end up knowing more than your mechanic if this is a sort of mish-mash hybrid.

But the base engine didn't start life as a ROW SC.

Thanks Tony, I will get those photos for you. I can locate the AAV, but I can't see a decel valve anywhere, I believe it may have been removed. The engine does slow down quite quickly causing a stumble when you lift the throttle so that does make sense the decel valve would be missing.

I believe someones intension was to backdate this CIS system using the euro parts. So that's the path I would prefer to take in getting this sorted out.

I agree! Hopefully we can get everything working nicely together using the euro CIS components. The car has been cammed as far as I know and who knows which pistons were used and what compression it may have now.

Would I see a benefit trying to source some larger euro spec intake runners?

The runners need to match the ports. If you have the small port heads, I suppose you could bore the intake ports and use the larger runners. They may not be easy to find? I think you may need an air box with larger outlets to the runners?

Even if there's a decel valve, many have them plugged with a golf tee. Why slow down the engine response by the artificial bypass, which I believe was done for emissions reasons ?

The O2 lambda is cool though since that improves fueling while cruising.

Based on what you have.......
 

Scott,

So you will need the following:

Ignition distributor (-001/-007/-009)
Decel valve
Thermotime valve
Auxiliary air valve
Aluminum vacuum lines for AAR & AAV
Rubber vacuum hoses for AAR & AAV
etc.

Tony

I've had my wideband O2 gauge installed and can see that I am running very lean across the board. Idle has been adjusted to 14.5 AFR, idles nice and smooth at 950rpm. At cruise it sits around 15-15.5 AFR, creeping up to 16 under heavier loads. Too high. Great fuel economy, but too high. Under heavy sustained loads or WOT the AFR is around 17 and creeps above 18 and that's where the engine definitely starts to lose power and chug. This is way too high. So I'm dealing with either a massive air leak letting unmetered air in, or fuel starvation issues. Perhaps both. I have a smoke tester due to arrive tomorrow so I can smoke the airbox and look for leaks. A previous owner had redone the airbox with epoxy and installed a pop off valve, so I'm not expecting a huge blown apart leak as everything looks tight, but things could definitely be leaking.

I also received my CIS pressure tester, so I did some testing and I thought I would add them to this thread for completion sake. I believe I am now chasing a few other problems other than a mismatch of components. I have a vacuum assisted WUR and these tests were performed without vacuum applied to the diaphragm. I have it disconnected right now when driving to richen the mixture, but it does lean out with vacuum applied so I can assume the vacuum assist is working. Once I get my system pressure in check I will reset the WUR pressures and also test the vacuum assist. This WUR was professionally rebuilt last year and tested good.

System Pressure - 4 Bar - Too low, should be at least 4.7-5.3
Cold Control Pressure @ 10C - .6 Bar - Too low, should be around 1 Bar
Warm Control Pressure
@ 1 Minute : 1.5 Bar
@ 2 Minute : 2 Bar
@ 3 Minute : 2.3 Bar
@ 4 Minute : 2.5 Bar
@ 5 Minutes : 2.7 Bar - stopped climbing at 5 minutes
Spec for my WUR is 2.7-3.1 Bar, so within spec, but barely.

Residual pressure tests:
Pressure after 10 Minutes: .5 Bar
Pressure after 20 Minutes: 0 Bar


So I know I have some issues with fuel pressure. I would like to get this sorted out then I can begin adding back the missing ROW control pieces (Decel Valve, Thermotime valve, AAV etc).

I would like to get my system pressure in check and also get the residual pressure to pass. What is the best procedure for testing the following components of the CIS system:

Fuel Pump output pressure, flow and check valve?
Fuel accumulator flow and residual pressure?
Fuel Distributor pressure regulator leak?

I would love some guidance testing these components or any other suggestions you guys might have!

Silver - you haven't answered the question of whether this engine does or does not have the big port Euro heads (which it didn't come with)? I'm not sure this would affect your lean issues, and your hot start issues. But it would be good to know. The '78-9 SCs have one set of CIS specs, the late Euro 3.0s have another, and the late US SCs have yet another.

It would be good to know if you have the late Euro high compression pistons, or the half point lower US pistons (unlikely you have the over a full point lower 78-9s). But it isn't easy to figure that out the way the port can fairly painlessly be determined.

You have by now got a diagram of the parts in the FD, and especially the pressure setting assembly. You are probably going to want to pull that assembly and add a shim to raise the system pressure - or replace with a thicker shim (a small washer, really). That has at least two small rubber O rings. So you can figure to replace those.

http://forums.pelicanparts.com/uploa...1616709432.jpg
http://forums.pelicanparts.com/uploa...1616709476.jpg

I am told that if the small O rings have gone bad, tricky diagnostic issues can arise. If your accumulator and the fuel pump anti-backflow valve are both fairly new, you might hold off just throwing those parts at your problem until you have dealt with your system pressure. Is there a way to learn if the professional rebuilders replaced the O rings in the FD pressure setting system? One would suppose so, as I recall the kits we can purchase to rebuild FDs come with them.

Resetting the control pressure ought not to be necessary. The WUR controls that, and after warmup the W part of the WUR has no effect. The only way to deal with that is to move the large iron slug the two lines attach to. To richen the mixture you would move the slug up. But it is not really made to be adjustable. But perhaps, if you don't have a big air leak somewhere, the mismatch of parts on this engine might require adjusting the slug?

The lack of the proper residual pressure, though, would seem not to be related to air leaks. It easily could be related to your injectors/FD letting fuel out the injectors with the engine off, though.

On a minor note, the CCP spec range for 089 wur w/vacuum applied is 1 to 1.4 at 10c. Without vacuum is typically .6 lower so your ccp seems within spec range. The afr at wot is crazy high/lean. Have you been able to determine if the lambda brain is working? Airleak is certainly possible but it’s really hard to understand how a working vacuum 089 wur can be complimented by the lambda brain. I thought both go rich, using different methods, under heavy acceleration so to see your afr numbers is baffling. An airleak big enough to cause that would seemingly also noticeably affect idle and all rpms. Something, in the past, was bad enough to blow the airbox so what is the underlying problem? Definitely an interesting setup and component mix to solve!!!!

I thought the same about air leak size.

I once had a cracked boot - the connector between the FD side and the throttle side. Sometimes the car ran fine, sometimes not well. It really acted up on a winter night time trip in the mountains with a girl friend with me, but by just good luck I identified the issue, and put a piece of tape over the crack. Ran fine for quite a while until I got around to getting a new boot.

The boot can be a bit tricky to get on and secured on both sides.

The oil tank breather line connects, on these models, to the middle of this boot. Which is why removing the oil tank cap can cause the idle to change.

Neither of these seem likely causes for way over lean running only at high RPMs. But at this point, lots of long shots are worth checking if not hard to do.

The smoke test ought to rule out a lot of possibilities.

I will go into more detail when I run a full suite of pressure tests now that I was able to shim the pressure regulator.

I now have the vacuum assist reconnected on the WUR as adding two small shims to the pressure regulator has raised pressure enough to cause the mixture to enrichen. I now have cruise at 14.5-15, and wide open throttle drops to 13-14. Mid throttle mixture leans out at some points a bit, but most I see now is 16.5, which has introduced a touch of surging on light throttle cruising.

With Afr down to 13-14 above 4000rpm the car is extremely fast. Way more than I ever expected. I definitely feel like the car does have 964 cams and possibly some other modifications with just how much power is found above 4000rpm, and all the way to 6000.

I will report back with my cold/warm control pressure tests tomorrow, and if my leak tester shows up I will see what's going on there. I have a feeling the boost in system pressure has increased my warm control pressure to the point where it's leaning the mixture more than it should be. I did see 3.6 bar pressure with the testor connected and system pressure was up above 4 bar now with the shims, but it didn't go much more than 4.3. I need to start fresh and see what's going on. With how drastically the cars performance changed with the shims I find it hard to believe I only raised system pressure .3 bar and in turn causes the warm pressure to go up so high.

As I said, I need to start fresh in a cold engine. Also, I plan to pull the AAR valve off to verify its function and will report back how long it takes to close off with power applied.

Before you start pulling valves off, recommend doing the leak test first since the former can alter the leak situation and then you'll be chasing your tail.

Just saw this thread - sounds like you already have a fuel pressure tester - I have an extra one ordered by mistake and am located in Squamish in case you are on the left coast.

Hey I appreciate the offer! I'm located in Kelowna.



I performed another pressure test today, it returned some interesting results.

I added another shim to the pressure regulator, it is now is fully shimmed and cannot be shimmed any further. I definitely have another issue relating to system pressure as with 4 shims in the regulator, I only got an additional .4 bar of pressure.

System Pressure 4.4 Bar (with regulator fully shimmed.)
Cold Control Pressure 0.6 Bar (same as before) w/ vac raises to 1.2 Bar
Ambient Temperature 10C again. So Cold pressure is within spec with vac attached.

Warm Pressure - No Vac/With Vac
1 Minute - 1.2 Bar / 2 Bar
2 Minute - 1.8 Bar / 2.5 Bar
3 Minute - 2.2 Bar / 2.9 Bar
4 Minute - 2.4 Bar / 3.1 Bar
5 Minute - 2.6 Bar / 3.3 Bar

Now, with residual pressure, I ran into that might be interesting..

With the valve closed to the warm up regulator, system pressure holds quite strongly. After about 10-20 minutes I still had 1.5 Bar

With the warm up regulator side open it bleeds off pressure very quickly, hits 0 psi within 30 seconds.

I also discovered that when I hook my mityvac up to the warm up regulator it doesn't hold pressure but instead drops slowly, not sure if this is by design.

I definitely have an issue with System Pressure being too low. Now the question is what is causing the low system pressure? Pump pressure? Fuel Accumulator? could it be an issue with the fuel return to the tank? Could it be a bad pressure regulator in the FD?

I am tempted to just replace the fuel pump fuel accumulator and FD pressure regulator just to rule those components out.

Is there a way that I can test the fuel pump pressure without using the fuel accumulator fittings? I don't have the correct adapter to go to the large sized lines on the accumulator. Can I pull pressure AFTER the accumulator where it goes into the fuel distributor to measure pump pressure as well as the fuel accumulator and fuel pump check valve?

Well.. This was unexpected. I pulled the skid plate on the front of the car to inspect the pump to confirm part numbers for replacement.

It looks like when they did the 3.0 SC motor swap they didn't swap the earlier pump out. Could this be the cause of my lower system pressure? After a quick google search the earlier CIS cars seemed to only run at 4.5 Bar.

http://forums.pelicanparts.com/uploa...1616799772.jpg
http://forums.pelicanparts.com/uploa...1616799772.jpg
http://forums.pelicanparts.com/uploa...1616799772.jpg

The little white spec book for the 1973.5T gives the same system pressure - 4.5-5.2 - as that given for the SCs.

That doesn't look like the CIS pumps I know, though. The Bosch has the wiring ring connectors on the end, not the side, of the pump. The fuel outlet is on the end away from the fuel inlet. And the outlet has the pressure retention valve either in it or on it. It is possible that this pump etc does not have the pressure retention valve at all! That would explain one of the problems.

This isn't a Bosch pump, nor a Bosch clone. A pump is a pump, and you are getting system pressure within (the low end of) spec. Maybe consider replacing the pump?

I googled the part number form Python and it does come up as a remanufactured pump for a 1976 911.. I then looked at 1973-1976 911 pumps and did come up with this Bosch one

http://forums.pelicanparts.com/uploa...1616856568.jpg

Notice the side exit for the fuel outlet as well as the side power connector, althogh slightly different.


I will replace the pump with one for a 1980 with the external check valve. I will also replace the fuel accumulator. I will also order the new fuel distributor pressure regulator so that I know the o rings are fresh and not leaking pressure.

So, you say this is an '80 Euro engine. The engine case # is for that. However, various anomalies are present here, and there may be more.

One of your pictures shows a K-Jetronic Oxygen Sensor control unit (silver box), with a Porsche 931 part number. Oddly, my Porsche parts catalogs don't show this unit for the 911s which came with them (1980-1983 US SCs) as part of the frequecy valve system to keep the air fuel mixture where Porsche wanted it. 931 suggests a 924 turbo?

However, as previously pointed out, Euro 3.0 SCs never had an oxygen sensor system. Without it, no function for the electronic control unit for one.

So what is the base tub? Is it ROW or US/CAN? If it was an '80-83 US/CAN (I think the Canadian cars had the US equipment?), then it came with

So you have a frequency valve (circled)?

http://forums.pelicanparts.com/uploa...1617162786.jpg

The control unit runs the FV. But there has to be one for it to be useful?

The picture you have of the backside of your fuel distributor shows funky stuff. Those stacked washers are for a bolt blocking off a port the FD originally had a fuel line for something attached to it - not how any car came from the factory. Perhaps modifying a US 80-83 FD to run without the FV would lend itself to this? Tony can probably tell, from your photo of its number plate, which FD you have. If it is a US FD for 80-83, it doesn't belong on a ROW set up car (though I suppose it could be made to work).

Then there is the ignition distributor. The ROW dizzy for '80 only has one vacuum line attached (and only one tube on the vacuum pot on the dizzy to attach to). You have a US distributor of that era. Which also suggests your FD is US, not ROW.

If the engine and car were manufactured together for the ROW, might the (partial) addition of some US equipment be a result of a Federalizing for a gray market car - a sort of fake to fool inspectors?

I suspect you have the Euro big port heads, runners, and air intake plastic box, because you have the ROW engine serial number. Thus you should (unless you change a lot of stuff) be looking at the Euro control pressure specs. The warm up "bands" on the temperature/CP graphs aren't the same, but that might not matter all that much. What probably would matter rather a lot is the warm control pressure (the pressure when the WUR's warmup feature is no longer affecting things, as it is designed to disengage after the engine has warmed up): 2.7-3.1 bar for ROW, 3.4-3.8 bar for US.

So what's the story?

Your photos also show

Walt,

The tub is a 1976 911, with Euro 930 bodywork.

The engine based on the 930/07 serial should be a US 1980.

The Fuel distributor is 031 - This shows up as 1979-81 ROW
The Air Metering Assembly is a 118 - This is correct for 1980 US (should be 070 to match the other 79-81 ROW components).
The WUR is a 089 - This shows up as 1979-81 ROW

Car is missing the Frequency Valve, Decel Valve and Thermotime valve.

The Distributor should be for a 1980 US Spec SC. I currently have the retard vaccum line disconnected, vacuum advance is in spec for 911SC, 5 Degrees no vac, 21 degrees at 6000rpm no vac, advances correctly under vacuum.

My theories right now are these:
1. Poor performing fuel pump and or leaking FD pressure regulator is lowering system pressure to 4.4 BAR with the FD pressure regulator fully shimmed.
2. Air metering plate is not a correct match to the FD. I believe this is causing a bit of an issue with enrichment under load and WOT. The 1980 US spec metering plate is expecting the FV to enrich the mixture in addition to the rest of the system, so therefore it doesn't provide as much enrichment based on a given amount of air moving the plate. The 070 metering plate is larger and has a different sides profile which would change how much the plate moves relative to the FD for a given amount of air, my theory is that it is designed to move the FD center valve more than the US spec metering plate which would also have the FV to provide additional enrichment.

This car has been pieced together by several people over the years. It was owned by my late father since 2006 and he was never able to get it running correctly. He passed a year ago and now I am making it my mission to revive the car.

The car starts, idles and runs nicely now. Now that I have a wideband O2 gauge installed I can see what it's doing under various running conditions. I disconnected the vacuum to the WUR as it was simply running too lean with it connected. It would enrichen under WOT as it should, but even with that it would only drop to 15 AFR under WOT and remain at 16-18 while cruising or partial throttle. too lean. Now it's around 14.7-15 all the time. I feel that with the increase in system pressure by replacing the fuel pump or the FD regulator I can get the mixture richer and be able to connect the vacuum line once more. Also the 070 metering plate should be a better match to the 031 fuel distributor (which was also used on some US spec cars).

The car pulls stronger and runs smoother than it has yet for me, so I am on the right track and having the wideband O2 and the CIS pressure gauges has given me a good grasp on what the system is doing. I believe that once I get the system pressure back up above 4.4 BAR and I get the correct metering plate, the car should run just like a ROW car should. I know the intake is from the 1980 US model and has the smaller intake runners so it won't be ideal, but it will be a big step forward.

I want to get the system fuel pressure up to where it should be and replace the metering plate. Anything outside of that (replacing distributor or intake assembly) I'm either going to install a 3.2 Carrerra fuel injection system with a standalone ECU or go to an ITB setup. I basically just want to get it running well enough to enjoy until I take the plunge and do either of those. After the fuel system is replaced I plan to work with my Porsche mechanic and do a 3.2 SS build.... But that's ways off.

Oh, as a side note, I believe the computer is simply to control startup sequence etc. There is a red "G" light on the tach that lights up and stays lit until you first pass 1500rpm and seems to keep the idle up a bit. Not really sure exactly what this is for.

Also, here is some reference material that I am using to determine ROW components.

Here are the Warm Up Regulators
http://forums.pelicanparts.com/uploa...1617174394.jpg
Here are the Fuel Distributors
http://forums.pelicanparts.com/uploa...1617174394.jpg
Here are the Airflow Meters
http://forums.pelicanparts.com/uploa...1617174394.jpg

I complete matched set for 78-81 ROW SC would be:

WUR - 089
Airflow - 070
Fuel Distributor - 031

I have the 089 and the 031, so it makes sense to try to source an 070 to complete the ROW CIS system. That way they should all work correctly together.