911sc Fuel injection issue...

[damiarosyrn 911]

Hello everyone it's been a very long long time since I've been on here and finally got the nervs to ask y'all what I need to do..
In short for years my box has probably been blown for a while and I may have been compensating by turning the fuel distributor a little to make it run properly. Finally broke down and removed the box and intakes and discovered my box had a significant crack which I repaired and everything was put back together as well as I remember..this is my second third time at it.... I recently attempted to fire it up which it did but the car will not stay on it would always shut off quickly.... I had somebody start my car while I lifted the lever inside the box, sorry forgot the technical name,and the car would stay on, it would run a little rough at the lower end but the car sounded strong , but as soon as I lifted off of the lever the car would die..
Anyone have any suggestions or I could start thank you for your responses?

[jma0506]

Unless you've baselined your air fuel mixture after compensating for the crack in your airbox, then it's likely you're running rich, also evident by lifting the air metering plate to allow more air into the system. Assuming you've tested your CIS and the pressures are all to spec and you've ensured there are no other vacuum leaks, you should follow the steps to re-baseline your air/fuel mixture and get it dialed back in.

https://forums.pelicanparts.com/porsche-911-technical-forum/758788-cis-troubleshooting-dummies.html

[E Sully]

If you turned the adjustment clockwise to richen the mixture to compensate for air leaks, you will need to reset it. Post 6 in this thread explains how to get back close to the baseline setting by turning the adjuster counter-clockwise.
Mixture Creep
To avoid flooding the cylinders while setting, pull the injectors and put them into containers. This would also give you a chance to make sure the injectors have a good pattern and don't drip. New seals should be installed when putting the injectors back in.

[damiarosyrn 911]

Sorry for the late response back , but thank you for your responses I'm going to try just something simple like left turning it to lean it out and see if that's all it is then if that doesn't work I'll have to get more in depth with gauges, which I'm not very good at with this car I've so out of the loop now.
thanks
Damian

[damiarosyrn 911]

OOhh...question...should I start out with a half or full turn or more counter clockwise to start out with?

[damiarosyrn 911]

Good evening everyone....it seems to be a long time before I get your recommendations and then get to do the tests but I finally got to hook up my gauges for the CIS tests but I was able to get system pressure of 4.5 bar but when I opened the valve to get the cold control pressure the gauge did not move it stayed at 4.5. Can someone advise me do I have a bad gauge or what first issue must I shoot for to correct this? Any help would be greatly apprec...My car has been sat up for almost 2 yrs but itl run if I depress the lever inside the air box?

[boyt911sc]

Originally Posted by damiarosyrn 911

Good evening everyone....it seems to be a long time before I get your recommendations and then get to do the tests but I finally got to hook up my gauges for the CIS tests but I was able to get system pressure of 4.5 bar but when I opened the valve to get the cold control pressure the gauge did not move it stayed at 4.5. Can someone advise me do I have a bad gauge or what first issue must I shoot for to correct this? Any help would be greatly apprec...My car has been sat up for almost 2 yrs but itl run if I depress the lever inside the air box?

If your CCP (cold control pressure) is the same as the SP (System Pressure) with the CIS pressure tester valve OPEN, the 2 most common culprits are:

• Fuel is not flowing through the WUR.
• The pressure gauge tester you are using has a Schrader Valve.

To test for blockage or restriction, disconnect the return line after the WUR. However, if your pressure tester has a Schrader valve, you are using the wrong tool. Hope you don’t have a HF gauge. Keep us posted.

Tony

[Schulisco]

Agree with Tony despite that the WUR got a screen on the input side of the fuel line cpming from the fuel distributor. As your car sits now for at least 2years this screen may be clogged due to rust and dirt from the detoriated fuel. Check this screen first. Perhaps you're lucky and it is the only culprit...

Thomas

[damiarosyrn 911]

Hello again and finally got to testing my gauge out first and i know now the gauge is fine after observing fuel flow as the valve was opened up and disconnected from the wur, thanks for the tip.
But I did first redo the test again and i now observed the gauge reading the same 4.5 reading and when i opened the valve the gauge dropped to zero and then went back to the same reading as if there maybe a restriction down the path.
Now if you guys can tell me how to open up wur and what to look for and the cleaning solvents? Is it possible to just blow air threw the inlet and see if there's flow thru?
Any help would be greatly appreciated guys..
Thanks Thomas , Tony, Ed, jma.

[Schulisco]

There are some threads here...can be easily found with search function here or via Google:
https://www.google.com/search?q=wur+blocked+bosch+cis+porsche+911

E.g.
https://forums.pelicanparts.com/porsche-911-technical-forum/1100375-wur-failure-question.html

[mysocal911]

Originally Posted by damiarosyrn 911

OOhh...question...should I start out with a half or full turn or more counter clockwise to start out with?

Always very small turns (< 1/8) at a time.

[damiarosyrn 911]

Hello friends, well I finally got to work on tearing down the wur and the four small screws sure were a problem unloosing before I stripped them permanently....Thomas and others I know u said check the screen but I don't see a screen? Looking down one of the exterior ports the larger one I believe an inlet from the FD?, looks like there might be a screen there is this what y'all are referencing to clean, if so how? The smaller port is clear after forcing carb cleaner thru it.....Everything looks to be in ok shape after looking at several videos of fellow pelicanites and I might be ready to put back together. The question mainly is am I ready to put it back together or is that screen in the larger port able to be clearned from the outside since it doesn't seem to be able to take it entirely apart, is the cylinder pressed in then?
Thanks ...
Damian

[Schulisco]

Originally Posted by damiarosyrn 911

Thomas and others I know u said check the screen but I don't see a screen? Looking down one of the exterior ports the larger one I believe an inlet from the FD?, looks like there might be a screen there is this what y'all are referencing to clean, if so how?

Yes, compressed air and a brake, carb or injection cleaner should do the job.

Here's a video from T&S Technik in Germany, they are specialzed in all CIS stuff...you can let YT translate it automatically. HTH

https://youtu.be/ryPuMdsk4zg

https://www.tstechnik-shop.de

Thomas

[damiarosyrn 911]

Good evening fellow pelicanites. Well i took the WUR apart and cleaned it out best i knew how and put it back and put the gauges back on it....well it didnt change a thing and the gauge did not move when i opened up the valve, damm. So i kinda confused now bc i thought if this is accuring and theres a plug in the the wur then gas would not be getting thru, am I mistaken? OUt of frusration with all this my FD is way off its marks by now so this is another problem to let yall know. Well then i removed the gauges and put the lines back together on the wur and and the car would not start, even depressing the air metering plate inside the air box. i then moved the FD adjustment screw the opposite way as before, turn the adjust screw now clockwise almost a full turn to start with and the car started but only with help depressing the plate. The car got easier to start and run the more I turned the FD clockwise, I know I'm probably way off adjustments too somewhere, but the car still wont idle by itself.
As before Im confused to why the cars getting fuel bc I thought my WUR was clogged due to gauge not moving in the cold pressure test? I thought I tested my gauge by removing the line which contains the valve from the wur and while the fuel pump was on I opened the valve and fuel did run out the line confirming there was not blockage in the gauge system and the valve works??
Sorry guys I'm not educated in this system and I've got a lot of questions and I want to drive this car ...haaa. and I don't want to pay a Porsche mechanic if its something I can do...Please educate me a little what I'm doing wrong.

[damiarosyrn 911]

Did I not clean out the wur enough by forcing compressed air thru the inlet, I didn't want to damage the screened inlet port with compressed high pressure. I tried to blow air thru the port with just my lungs and it didn't work, was it bc it needs more pressure than my lungs? or does it mean its super clogged and clean it again with forced air , can it be damaged doing this? I saw several videos and I never saw them mentioning the inlet port should be air free flowing. The other two holes (vacuum) and fuel outlet hole were free from obstruction on the wur.
My other question if I bypass the WUR and use the CIS gauges as I learned, will and can the car operate where I can then get the FD in a proper status and move on from there?

[boyt911sc]

Damian,

What are your CCP and WCP. How good is your residual pressure? Thanks.

Tony

[Schulisco]

Damian,

you urgently need to fully understand CIS before you can help yourself and sorting the issues of your car out. Therefore I heavily recommend to study the following videos, literature and websites:

https://cis911primer.com/home.html
The whole website, it explains in detail all CIS components. You need to know what every component does. Only then you're ready for the next step to understand how all these work together. No one is superflous, any component has it's purpose.

All that stuff is also linear readable in this:
https://files.bmwclassic.nl/E21/K-Jet/Bosch_K-Jetronic_web.pdf
It's worth reading both.

The very basic self study program from VW/Audi introducing CIS from the 70ies is also available as PDF, but unfortunately only in german. The important numbers are 11 and 44:
http://www.volkspage.net/technik/ssp/ssp/SSP_11.PDF
http://www.volkspage.net/technik/ssp/ssp/SSP_44.PDF

Porsche started to develop the CIS with Bosch originally from the late 60ies:
https://www.bosch.com/stories/history-of-electronics/

This video I found shows pretty good on how the relations between the sensor plate, the WUR and the fuel distributor and how they interact, exemplary on a nice R5 Turbo:
https://www.youtube.com/watch?v=L191GFeddIUe

This is a oldschool original education video by I suppose VW/Audi:
https://www.youtube.com/watch?v=a4fJAfXYxWk

The fundamental understanding you need:
The fuel distributor is needing the control pressureall the time! There must be always control pressure bing applied against the plunger of the FD to limit it swinging too much due to sucked air. This is very fine balanced system which urges for precise setup. So the WUR gets never fully closed, it only varies the control pressure!

The best troubleshooting and adjustment videos on the net is the video series for the 2.7 911 from KlassikATS:
https://www.youtube.com/watch?v=WZzFoeICSLw&list=PLkWFofpgz2OgF9FdliKnlzuY0pygqRkMj
Especially these:
https://youtu.bedv1g_2Mq4Ck
https://youtu.be/K-OvjlkrgNo
https://youtu.be/slCzVrrST2Q

Concerning the WUR and the FD I recommend to let them be overhauled by a specialist. Both are the most critical CIS components for a proper running engine. DIY them is dangerous, as you can ruine your engine too due to a false overhaul of the FD: When single cylinders gets too less fuel and others too much the mixture basically seems to be ok still while it's not. In extreme situation this can destroy that piston or valves, as aircooled engines are quite sensible to that. You need a test bench to adjust it properly. Those adjustment screws are only for fine tuning of a working FD. If it's bad or either never or long time ago have been overhauled yet, then better let it overhauled by a specialist!! Saving money here is wrong!

Thomas

[boyt911sc]

Damian,

It will require only several minutes of my time to test and evaluate your WUR. Send it to me and I will have it shipped back to you a day after receiving your package. Include a return shipping label preferably a UPS. PM if you are interested.

Tony

[damiarosyrn 911]

Thank you Thomas for the links ill start looking at them ...

I have a question, after i cleaned and put the wur back in i then started the car with a friend while i pushed up on the metering rod lever and the car ran , not perfect but it ran just as long as i depressed the metering lever. The question i have ls, if the wur was clogged wouldnt that cause the gas from free flowing thru and the car not run??

When i had the gauge hooked up the only thing i could get was the system pressure which was up around 4.5 or 4.7 bar, then opening the valve the gauge would drop to zero then go right back to 4.5. To add, i dont know if i have 12v coming out of the electrical plug.

In the mean time im going to look thru my box of parts and look for a spare wur....Thank you Tony i appreciate the offer i may take you up on it...

Damian

[boyt911sc]

Damian,

Hope you have not given up troubleshooting your CIS problem/s. Have you tested and verified the condition of your pressure gauge kit? Does your gauge kit have any quick disconnect fitting in it? A picture of the gauge kit would help. Thanks.

Tony