How To Diagnose And Fix Your Porsche C.I.S Fuel Injection System
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- Опубліковано 8 вер 2024
- The C.I.S Porsche engine is great if it is running well. We find a big difference between running and running well. In this lesson, we take a look at an engine we just rebuilt. We left the fuel distributor and the warm-up regulator as is to test them before deciding if they needed a repair.
Lucky for you they both had issues. We work through the process, and with a little more time in the car, we can get this engine bedded in and running well for a long life.
This is a long video, and you may want to watch it a few times to pin down your problems.
The must-have is a pressure gauge. The light is a bonus, but another harder to get must-have is the gas analyzer. Maybe you could take it to a shop with one.
We still have some tuning to do and will grab more footage. As well as the restoration of the C.I.S system lesson. We are editing that one now!
Noid Light
amzn.to/3y2ZSUz
Fuel pressure test kit
amzn.to/3SSo7mf
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An absolute must-watch for any Porsche CIS owner. Very well done and extremely clear.
Thanks Julian
Another extremely informative installment.
This Porsche content is by far the best available on UA-cam
Totally agree. This is the absolute best Porsche channel on UA-cam
Thanks Adrian
Glad you think so!
Thanks for watching
I am new to Porsche with a well-worn ‘77 911S. This and your other CIS videos opened the book for me. Excellent instructional videos.
Thanks John, glad that the videos helped.
Thanks for watching
Kurt
Excellent video! I know how CIS works, but still watched the whole clip as you explain it so well.
Thanks
Kurt
What an ACE !! I ditched my CIS and running 40 IDA Webers but still have CIS on my VW rabbit pickup so this in a great insight. Thank You.
Your welcome,
Kurt
Great video. I encourage anyone with a CIS car (Porsche, BMW, Merc, Ferrari etc) to look at FrankenCIS especially for those that have done some modification. I'm running it on a Porsche 930 with big cams, bigger turbo and some other mild mods and using it to control CIS and ignition getting 425 rwhp without going to EFI. Great option.
You really need to know what you are doing with these units. There are several options out there for electronic WUR. But I would not recommend them for most people as you can do more damage than good if you do not know what you are doing or do not have the tools to correctly tune and make fuel settings.
Kurt
Well done one of the most informative videos of all time.
Glad you enjoyed it
Thanks
Kurt
Great information, I have a Mercedes 500 slc with a few problems after not using it for a while. Have removed the WUR and ordered a new repair kit. I do wish I had watched this video first ! Have brought the same gauges you use, but didn't realise I could check everything, without the engine running. I may put the unit back together and check, before rebuilding. Thank you for a great video, I will watch the rest now
Kayleigh,
I would not recommend using a repair kit unless you have access to a calibration bench where you can correctly calibrate the warm up regulator after rebuilding it. I would send the WUR to CIS Flowtech and have it rebuilt.
Kurt
Absolutely fantastic and though explanation. I have a 6 cyl Mercedes with a M110 engine and this session is highly appropriate.
Glad it was helpful!
Thanks For Watching
Kurt, Your video is excellent!…Reading about how these components work is one thing however, seeing the engine outside the obstructions of an car with the various components and watching and listening to your very clear explanations is ideal!…Great job!!
Thanks Michael,
Glad you enjoyed it
Kurt
c est la premiere fois que je vois une explication sur kjetronic aussi parfaite
Merci beaucoup
This is such a fantastic video. Thank you for breaking down the CIS system so clearly and logically.
You are welcome
Kurt
Excellent information and diagnosis process. This gives me a much better understanding of the system. Thank you!
Cory,
You are more than welcome
Thanks for the in-depth video. I now know how to track down the 1 cylinder that keeps popping. 👍🏻
Glad to help
Kurt
Best video I've seen on CIS diagnostics so far!
Thanks
This video is so informative and helpful. Thank you from an owner of a Lotus Esprit with CIS.
Your welcome.
Kurt
great intuitive video on your Porsche engine..
Thank you!
Kurt
Excellent, as usual!
Thanks, Chuck
Excellent! Trying to decipher the blend of accents!
Glad you liked it!
Kurt
Excellent tutorial- thank you
You are welcome!
Kurt
Awesome video, Great explanation! Thank you for taking your time to make this. Also shoutout to the camera guy.
Our pleasure!
Kurt
Just what I wanted to know thank you.
Glad to help
Excellent Job ❤
Thanks 😄
Kurt
The Bentley Bosch FI book by Charles Probst is excellent, but you actually show how the components all work together. A more sophisticated version of a Weber IDF's circuits. Thank you.
Yes all fuel injection systems can be related to a carburetors operation. If you understand how a carburetor works then you will have no problems with a fuel injection system.
Thanks
Kurt
Best CIS video I’ve ever seen!
Thanks
Kurt
Hi Kurt,
I have a technical question related to my 1978 3.0 CIS engine. A couple of the nylon fuel lines going from the distributor to the injectors are nicked. I decided to rebuild them and bought 15 feet of black nylon hose which complies with the technical specs regarding pressure and chemical resistance. The hose is 4mm ID x 6mm OD.
When comparing with the existing hoses I realized that the existing hoses are 2mm ID x 6mm OD. Some forums claim that the 4x6 are fine while others claim that these are not fit because they “pulsate”. I don’t really trust the forums and have been unable to find a definitive source of information regarding this issue. I wanted to ask you whether replacing the existing injector lines with the 4x6 mm would be acceptable or not as finding the 2x6mm is all but impossible in Mexico. As always, I look forward to your comments, your advise has always been on point. Thanks for sharing your knowledge. Best,
Mario
Mario,
The injector lines used on that car are somewhat unique in both there thickness and the extra layer of abrasive protection applied to the lines. If you were planning on re-using the fittings they will not fit your new lines, (4x6mm). Yes they will slide on but may also blow off. The correct line size is available in a Cohline brand although it will come without the abrasion resistant coating. I have found it cheaper and easier to just buy the correct injection hoses that come with the correct size pipe and fittings and the abrasive protection coating applied.
Kurt
Very informative! I did notice however that you have the vacuum and atmosphere hoses reversed on the WUR. For the 1977 production year and the 033 WUR the top hose should run to the top connection on the throttle body (as it does) but via the outer connection of the thermal valve where it couples with the distributor vacuum. And the bottom connection on the WUR should run to the lower connection on the throttle body (where in the video the distributor vacuum hooks up). So basically for the first 30 seconds of startup the thermal valve is now limiting atmosphere to the WUR instead of vacuum. Yet your engine seems to run very well so I'm surprised by this. Would you mind explaining how this can be? Again, great video. I enjoyed watching it! Thanks.
Diederick,
Yes, good eye on the vacuum connections. When I first assembled I put everything together just like the 911SC configuration. On the test stand, it ran well. However, once I put the engine in the car it suffered from a lean misfire at 2000 - 2500 RPM. I revisited my vacuum layout and after hitting myself in the head reconfigured, to the 1976-77 2.7L layout. The problem was then solved, the lean stumble went away and the car continued to perform as it is supposed to. What this re-enforces is that no load is no test. And even though the engine ran well on our test stand in the car its performance was not as it should have been. Thanks for watching and thanks for keeping an eye on what we are doing.
Kurt
Another great video Kurt. Thank you so much. Does this one precede the CIS Fine tuning video that you did, with the motor in the car? I noticed how you had the vacuum lines connected to the Decel Valve as an SC. I'm learning a lot from these videos and it makes a huge difference than searching through forums and only getting the opinions and recommendations from people that are ill-informed. Very much appreciated.
Hi Jason, your comment made me think of this comment from 2 years ago. We did have the 77 set up incorrectly as an SC. We found out when the engine went into the car. Thanks for watching, S
Diederick,
Yes, good eye on the vacuum connections. When I first assembled, I put everything together just like the 911SC configuration. On the test stand, it ran well. However, once I put the engine in the car, it suffered from a lean misfire at 2000 - 2500 RPM. I revisited my vacuum layout and, after hitting myself in the head, reconfigured it to the 1976-77 2.7L layout. The problem was then solved, the lean stumble went away, and the car continued to perform as it was supposed to. What this re-enforces is that no load is no test. And even though the engine ran well on our test stand in the car its performance was not as it should have been. Thanks for watching, and thanks for keeping an eye on what we are doing.
Kurt
By far the best instructional video. Thank you Sir
Thanks
Kurt
@@klassikats I would like to ask you if I may..
I have a 76 930 it started to accelerate on its own right after I turn it on
The tach goes all the way to 7 RPM I have to turn the key off immediately
I already clean n lub everything from the gas peddle to the throttle
I also check with a light the worm up regulator for current
The light does not come on
Could this be part of the problem?
Thank you in advance
@@adanponce4401 Adan ,
it sounds like you have a large air leak in the intake system. The engine won't rev that high by itself unless it has a source of air and fuel. If it was just a stuck open throttle, then you would find that pretty easily. Also, no power to the WUR will not cause that issue.
@@klassikats thank you so much for your time taken to unswear!
I’ll check for air Suction
Good job sir
Thanks
Kurt
Wow thank you!
You're welcome!
Kurt
Superb video. Thank you so much for sharing… much learned!
Glad you enjoyed it!
Kurt
awesome great explanation
Thank you!
Extremely well done and helpful.
Glad it was helpful!
Kurt
Thank you so much for all your videos. Your CIS ones have been particularly helpful. Appreciate your work and expertise. 1983 911SC here in upstate NY. I am currently replacing fuel pump, WUR, fuel filter, and a couple fuel lines. Hoping she'll be running good soon. Anyone know if I will need to adjust my mixture after installing new WUR? At this point it looks like everything is good - 4.5 bar fuel pressure from fuel distributor. Last component going in is the WUR. Hopefully this week. Thank again!
Yes the fuel mixtures will need to be adjusted.
Kurt
Thanks again. I figured that 3mm adj. screw would need a little tweek as well as idle screw. Appreciate response. @@klassikats
Very detailed and informative.Thanks
Glad it was helpful!
Kurt
Great video. This was super helpful! Thanks!
Glad it was helpful!
Absolutely awesome documentation. Thanks for the great information
Glad you enjoyed it!
Thanks for watching
Superb video and a massive help 👏 👌 thanks
My pleasure 😊
Kurt
CIS Made Easy. Only took 30 years of practice, eh? ;-) This is a FANTASTIC resource, and I very much envy you your skill and equipment. I will be watching it REPEATEDLY. I'm trying to resurrect a 77S after a Big Bang. After many semi-to-unrelated twists and turns, my current problem is not having access to the FSM and the pressure graph for the 77 033 WUR. I see that the 78 069 WUR has very similar specs, and the graph is present in my Bentley SC manual, but similar isn't really good enough. Any suggestions?
You are correct in that you have to use the right graph for the actual WUR part number you are looking at. We have most of that information on our website. Here is the link to the 033 pressure information on our site.
www.klassikats.com/porsche-1976-0438-140-033/
thanks Kurt
No problems until the fuel hoses were all changed. If we increase the fuel, the system is readjusting the mixture to lean again. I will have the shop check the fuel pressures. Thank you
Your welcome.
Kurt
Sudden problems with a part of the CIS system. When warm the 76 911s won't idle when warm. No problem with start-up but as it gets warm the rpm drops and then when operating temp is reached, there is no idle. It also runs rough with a few pops. The fuel system (pump, and lines were replaced about four months ago and it worked great. The problem started when the idle dropped a few 100 rpm when warm. Then after a few drives, it will not idle at all. I am thinking there may be a leak (hose) at the warmup regulator? The box and pop-off valve are in great shape with no cracks.
I would look at fuel pressures, sounds like the control pressure may not being working correctly.
Kurt
Well filmed, narrated and crystal clear instructions make this the best instructional CIS video I have seen. One question, my 74 Fuel Distributor has a banjo fitting with an additional fuel line running to the primary pressure regulator ? Not seen on your set up. I assume that line needs to remain in the test loop, correct ? And does that component have its own test procedure ?
Steven,
Yes, your car is a much earlier version, and the warm-up regulator on your car had no acceleration enrichment built in. So on your car, they use a mechanical throttle valve hence the connection to the control valve circuit at the fuel distributor
WOW, this guy is awesome !!!!
Thanks
Kurt
Wish I had seen this before I decided to convert my SC to EFI!
Yes a properly set up and operating CIS fuel system works extremely well. It is also very robust and because it is not electronically controlled it allows for a much better and stronger ignition system in the form of a CDI. Making the car very reliable and dependable.
Thanks for watching
Kurt
Great stuff, thank you!
Glad you enjoyed it!
Thanks Kurt
Well done!
Thanks
Kurt
Fantastic video ! Super informative!!! Thanks so much !
Where is your accent from? I can't quite place it
Thanks
Kurt
Excellent as usual !
Enjoyed the content.
Any recommendations on shop manuals?
Thanks John,
The only shop manuals that I use are the factory ones. The next best would be the Bentley series of manuals. One thing I will say about some of the after-market shop manuals out there is how poor the quality of information can be. Many of these books use opinion instead of facts and they tend to be missing a lot of key information. The Porsche manual system builds on its self. This means that depending on the year model of your car you may require anywhere from two to ten of the factory Porsche books. The factory manuals are expensive but are still available both new and used.
Thanks for watching
Kurt
Update on the test kit. You do need to check if the kit has a shut-off ball valve. Check out this kit. amzn.to/3SSo7mf
Dear Kurt, first, thank you fro sharing your knowledge with the audience - Porsche enthusiasts. I appreciate that a lot. I have learn about you from the last Mike's video - he is also great. Personally, I have a 3.2 911 with DME fuel injection, but I have very much enjoyed. I would like to hear your opinion on one thing that bother me lately, if you allow. When I accelerate, I hear a whistle in every gear. The whistle comes after, let say, an inch in the throttle and stays for about half an inch farther in, and after that stops. What is your opinion? It would be awesome, if you response. Best regards Lukas
Luckasz, That could be a number of things from air moving over the throttle plate, or air moving through the air flow meter or the idle air control motor. It really something I would have to hear to really be able to nail down. I would say that if you are not experiencing any running issues, then I would not worry to much about it.
Kurt
@@klassikats Many thanks Kurt. I have heard something about the right possition of the throttle plate. Could it be that this part change its position somehow? is there a spec on that ?
@@lukasztrembowski3015 Lukasz, Yes there is a setup procedure on that throttle butterfly.
though I doubt that the actual butterfly would be creating that kind of noise. I would expect it to be coming from a bypass channel where the air is restricted through a passageway. You could perform the base idle speed setting by bridging the test plug on the fuse panel and setting the base engine idle speed on the bypass screw and see if that helps. It could also be a carbon issue. Removing the throttle housing and cleaning everything to remove oil and debris may also resolve your issue.
Kurt
Great video!
Glad you enjoyed it
Thanks for watching
Hi, great vídeo. My car a Gasoline passes straight to the injector. I have already visually checked if the butterfly is closed, and even though it is 100% closed, the fuel flows into the nozzle and drowns the car
Then check your fuel pressures.
Kurt
good morning. I would like to congratulate you for the excellent video. I was able to solve my problem by following your checks and tests step by step. thank you very much
Glad to be able to help.
Kurt
Thank you for this! A lot of great information! Been trying to figure out for a while Now why my 78’ SC 3.0 keeps stalling out when I lift off the throttle! Must be an issue with the deceleration valve @41:55.
Jimmy,
if the engine is dropping back to idle to fast it will cause stalling. Also check the fuel mixtures using a gas analyzer. If the engine is too rich or to lean it will also stall when coming back to idle.
Good luck with your repair and thanks for watching
Kurt
Thank you for your videos, they are all very well explained and have lots of good information to avoid mistakes. I am looking for fuel hoses for my 911 81 Targa and was looking for same esterior look as the cohnen 380 (wrapping in spiral fashion) but able to cope with ethanol. Cohline 2240 for engine bay is what i found but do you have any sugestion about this? What do you use? Thank you. I also follow your BMW videos, M54 engine on my e39 but I like to watch your quality work!
So none of the rubber hoses are going to be ethanol safe. The other issue is Cohline has discontinued the style of hose that you are looking for. There is not a lot we can do with ethanol fuels. We have experimented with using polyamide hoses in some applications as they are ethanol safe. the issue is sometimes working with these types of pipes can be harder. Also, they work with push-on fittings and do require using screw fittings.
Kurt
@@klassikats Thank you, Will check the polyamide hoses. I Hope there is any option that Will keep the original look as much as It can be kept.
One of my favs! Will watch over and over. Superb content.
Question 1. during WUR tests. As the fuel pump runs isn’t it dumping a ton of fuel via injectors into the cylinder through the entirety of the test? Enough to be bad while it sits and worse w bad leak down %?
Question 2. At what point do leaky injectors show up in the pressure testing? You mention the oring on the FD as a contributor but could worn injector springs also show up in the falloff speed you mention when testing residual pressure?
No, it should not be. Fuel should only be flowing through the injectors when the sensor plate is lifted off the seat by the incoming air. Now that doesn't mean that fuel cannot be entering the engine. If the senor plate height is incorrect or the fuel mixture screw is set overly rich fuel can indeed flow into the intake system. The other reason would also be worn fuel injectors where the internal seating springs have failed causing the injectors to leak or drip.
In the first instance, you will hear the injectors flowing as they will sing when fuel is flowing through them. This is the indication that there is an issue and you would stop the test and resolve that issue first. The second issue is a lot harder to notice, however, it is easy to check for by just pulling out the injectors and checking for leaks if you suspect that it is an issue. A misfire at start-up that clears itself quickly is an indication of leaking fuel injectors.
Thanks for watching
@@klassikats On this issue Kurt, my injectors are new and I am going to check the plate height today. Beyond that, can the cold start injector pump enough in to cause fuel to enter? I had a pretty good amount coming out, I am assuming my plate height is wrong, but would CS Injector be able to do it as well? My understanding is that it should fire momentarily and then stop.
Amazing video again. Thank you. Super helpful
Glad you liked it! S
Kurt,
Great instructional videos!
I live in NJ.
How do you maintain and get parts for your Sun distributor tester?
Is there a location to buy a used tester as I believe the company no longer exists.
Thank you
Victor
I use "paramount" for parts and service. He is in Michigan.
Kurt
I have an 81 911 SC. Did the pressure check and got these numbers:
Ambient Temperature: 28.44°C
Control Pressure @ Ambient: 2.05 Bar (Low Spec: 2.844 Bar)
System Pressure: 4.8 Bar (Spec: 4.5-5.2 Bar)
Control Pressure Warm: 3.55 Bar (Spec 3.4-3.8 Bar)
System Pressure Warm: 4.8 Bar (Spec: 4.5-5.2 Bar)
System Leak Down: 1.6 Bar @ 10 min (Spec: 1.3 Bar minimum)
1.3 Bar @ 30 min (Spec: 1.1 Bar minimum)
System Leak Down Control Pressure: No Change
Is my control pressure too far out of spec? It does backfire if I try to take off on a cold start so I have to let it sit a minute.
pressures dont look bad, would need to know the WUR number to confirm exactly. What are your fuel mixture settings? CO, HC, CO2, and O2 numbers?
Kurt
@@klassikats I don’t have the WUR number handy but I do know it’s the one for the 81 model year per the Bentley manual. As far as testing every thing out, this is about as far as I’ve gotten. I thought about making sure there aren’t any vacuum leaks as well.
Great detailed video, what company do you recommend to rebuild the fuel Distributor?
I use CIS Flowtech in Alabama
Kurt
Nice video!!! Very comprehensive. Do you focus just on Porche CIS or some other German brand like Mercedes? I'm asking due to I'm having issues with my MB 190E 2.5-16 CIS injection and need some help.... Thanks!
Fernando,
I am a Porsche specialist which is why this is focused on Porsche. How ever the CIS injection system principles are the same from vehicle to vehicle. There can be some differences in how the system operates. For example MB uses a series of electronic sensors and control valves to improve the Basic CIS system and controls.
@@klassikats Thanks for your reply. Is there chance you can guide me where to look to solve my problem? Thanks.
just WOW !
Thanks
Awesome video! Can you provide part number for the Bosch Noid/injector test light?
There's a link in the description but just in case here's the link to the kit we use on amazon. amzn.to/3nap7BB
Thanks for watching
Kurt
have you got a full test on ke jetronic video i can watch too..,
Many Thanks,
Paul..
No, Not yet .
Kurt
Great video! I am about to perform the injector flow measurement on a 930, which has steel injector lines instead of plastic. Do you have any suggestions on how to maneuvre the injectors into the measuring cylinders in this situation?
I just use a set of polyamide lines to just run the measurement/flow test
Kurt
@@klassikats Thanks Kurt - that does make sense but I'm not in a position to have a spare set of nylon lines lying around. What about clamping some flexible fuel hose to the outside of the injectors and redirecting to the measuring cylinders? Unfortunately I won't see atomisation/cone shape with this approach...
It will sort of work. you might lose some volume on the sides of your hoses as you are going to be relying on gravity to drain into the measuring vials. Also be careful not bend up your fuel lines from the fuel distributor to injectors using that method.
Excellent CIS content. Thank you sharing your knowledge. I got a question here, since I started with completely de tuned engine. After initial airflow body setup than WUR setup comes the mixture control. I noticed it has quite an influence on the control pressure. Would this mean that the pressure compensator is not really up to the task? It did pass the warmup test with flying colours.
Mareek,
Are you talking about KE-Jetronic? like the system used in the 1980 and up 911/930 USA models? If so, then the lambda control solenoid will modify control pressure to adjust fuel mixtures when in the closed loop. However, unless you are tapped into that fuel circuit on the back of the engine, you should not see it on your pressure gauges. If you are seeing large fluctuations in control pressure not related to vacuum inputs, then you more than likely have a flow/volume issue.
Kurt
@@klassikats Kurt, thank you for the prompt response. Yes, I definitely have an issue with lambda control and I’ll tackle it on Monday.
Kurt
Excellent instructional videos.
Where do you buy the graduated plastic cylinders to measure the injector spray pattern and volume?
Also on a well running 1987 930, I have replaced the fan belt with a new Porsche belt.
I have installed 6 shims between the outer pully and the tensioning washer with 1/4 inch deflection with the ac belt disconnected.
I am not able to rotate the engine by turning the alternator nut to adjust the valves.What would you suggest?
I appreciate your time>
Thank you
You can find them here amzn.to/4bLq5Mz at amazon. If the belt tension is good, then there is just not enough friction between the belt and the pulley to turn the engine through its compression stroke. this is normal.
Kurt
then you must remove the plugs to adjust the valves?
thank you@@klassikats
Victor
@@victorvillari-fc1rz with the plugs out makes it easier to turn the engine and you can do a leak down and plug check at the same time.
@@klassikats thank you
Excellent video. Any adjustment differences you would suggest regarding straight gasoline and E10 fuel? AFR for gasoline is 14.7::1, but E10 is 14.08:1 Will the CO and H2 be the same?
ExSully,
When setting CO% keep an eye on the HC, if the CO% is higher but the HC are staying low then you should be just fine. Measuring AFR is a little tougher as you need to be driving to do that and only under certain conditions will it actually show that 14.7:1 ratio. Todays fuels are certainly not what the were back when these cars were new. It is always a good idea to constantly monitor engine performance and gas mileage and modify your settings as required.
Thanks for watching
Kurt
Well Done! Clear & concise! Do you have same for KE-Jet?
We don't have a KE-jet car in the shop right now, but you never know. Thanks for watching!
Hi, In the beginning you used a little LED test light for Warm Up Regulator, Do you have a link to that part?? Thanks
here's the link to the kit we use on Amazon. amzn.to/3nap7BB
Thanks for watching. S
Great explanation, thanks for the video. I do have one question though. I have a Porsche 928 with similar CIS system and a workshop manual. In my manual it is stated that the control pressure in cold condition must be measured with a vacuum applied to the vacuum port of the WUR. I haven't seen you do that in your video. Shouldn't you apply a vacuum (of 450mbar) while measuring the cold control pressure?
Cold control pressures are measured in two ways, with and without vacuum. Without vacuum will directly affect the cold start and with vacuum will affect the cold running of the engine. We have a video specifically on the vacuum portion of the circuit. You can see it here ua-cam.com/video/Ii5k773lwKs/v-deo.html
Thanks
Kurt
@@klassikats thanks for the extra video, it gave me more insight in vacuüm operation in the cis system. My workshop manual only specifies a cold control pressure with vacuum applied. It also has a specification on warm control pressure with and without vacuum. Do you happen to have the cold control pressure (without vacuum) specification for my car (1980 928s, euro spec)?
@@berndsen1984 Cold control pressure 20 degrees C ambient temp, no vac, engine off, 1.1+/-0.2 Bar. Thanks for watching, S
Kurt,
The fuel test kit does not include a ball valve to isolate the WUR.
Do you have another recommendation?
Thank you
Victor
victor,
Here is the link to another one with the ball valve
amzn.to/3SSo7mf
Thanks
Kurt
@@klassikats thank you
Q. Replacement injectors - i.e. currently have old 009’s (930). Porsche recommends 017’s as a replacement. Lots of theories out there about fuel volume delivery between the two. I’m more interested in open pressure comparisons done on a bench test to diagnose part of a hot start issue.
Open pressure on the new injectors is 15-20 psi higher compared to a NOS 009 baseline I’m using along w Tech Spec manual for comparison. Porsche recommends 017s for older 3.0 FD and newer 3.3FD 930 cars.
Does the increase in crack open pressure between the older and newer part # indicate better spring strength and therefore better injector sealing after engine shut off or more to do with amount of fuel delivered?
Fancypants,
Would love to know what your hot start issue is, so I can point you in the right direction. When it comes to a Fuel injector they are a calibrated part. This means that the flow rate of the injector will be matched to the flow requirements of the system and the engine it is installed in. A change in the cracking pressure will not result in a change in the flow rate by itself. The flow rate is determined by the nozzle diameter. Parts are constantly updated and revised as information on their performance comes back from the field. The update in cracking pressure would be to correct a leakage issue and not a flow issue.
Thanks Kurt
@@klassikats part of diagnosis so far was replacing Fuel Accumulator - bad diaphragm fast falloff on residual pressure was a tell. Replacing solved a chunk of both cold and hot related start issues.
Cold start fires up in first or second try now, not 15-20min in the past. Assumption is CSV works, plug tests pos. Hot start still a concern. WUR back from rebuild will recheck psi numbers. Also suspect Fuel Pump check valve & leaky injectors as contributing factors. Have new 017s but concerned 009 myth of flowing better may be true? Test fuel delivery in tubes like you did or just install them?
Crack open on 009 inj is low per spec. All attached to 930 - 3.0L, 016 FD spec 5.9-6.4 @ 150l/h. Overall, 5 cyls burned evenly tad rich while #4 was very black and oily. Leak down %’s not ideal but top of range, tested cold not warm.
On the warpath to keep CIS vs EFI.
@@thinkerdoit I would have no issues using the 017 fuel injectors and have had no problems with them at all. Fuel mixtures can and will play a large part in hot and cold starts. The correct fuel mixture setting is also responsible for the entire fuel range as it changes the center piston position in the fuel distributor. If you suspect a volume difference between cylinders then I would, by all means, do a quick flow test. you mentioned leak down numbers were not good? what were they? Engine internal condition plays a large part in total engine tune. Sounds like you are on the right track, just need to chase down all the details. When set up correctly these cars should always start and run easily.
Kurt
hiya.., i have 1.6 rs turbo and has been sat for 10!years and never had an issue with fuel injection distributor but now have no fuel to injectors but have pressure to cold start.., have removed eha valve and added 1/4 turn clockwise to see if the valve was blocked., then did have a pressure under cranking and pressing on air flap on ke jetronic system but after leaving it for a few hours again i have no fuel to injectors but now even with cranking and holding flap down fractionally it's not getting fuel to lines.., was wondering if this is an ecu fault or failing fuel distributor
Paul,
So CIS fuel systems do not like to sit for long periods of time. What usually happens is that the fuel evaporates away leaving just the additive package that turns to a glue like substance. More than likely this is what is causing your issue. I would confirm that you have the correct incoming fuel pressures and flow volumes. Make sure your electrical inputs from sensors and grounds are correct. And that your pressure differential valve is getting a signal from the control unit. If all of that is correct pull and send the fuel distributor out for repair.
Kurt
I have a 1982 911SC, where are you located? My engine could use an expert to make adjustments.
We are in Flagstaff, AZ
Kurt
Where is a good place to go and find the k jet manual for a ford capri 2.8i? I want to run the sames tests you have performed.
Not sure where you would find that information. I would try searching google with your WUR number and see if you can find any of the pressure specifications.
Kurt
I ordered one. Thank you
How do you test the coil on a 1987 930?
The decal shows not to place an ohm meter across the terminals.
Victor
That is only when the engine is running. You can measure resistance across the coil terminals with the engine off and the coil disconnected. However, this will not tell you much. The only real way to test coil function is to use an oscilloscope and look at the wave forms as energy is moving though the coil.
Kurt
@@klassikats Kurt
I am ordering a restored CDI box from Parts Klassik. Is it imperative to not use a 1000 ohm rotor, which is the only one available today?
Also what brand of oscilloscope should I buy to check ignition on the 1987 930
Thank you,
Victor
Partsklassik has a 5000 Ohm resistor available that should be installed into the coil wire. There are so many oscilloscopes out there to choose from. I use Siglent scopes but I would just choose one that suits your budget and immediate needs.
Kurt
THANK YOU,
Victor@@klassikats
Hi! I’m hunting a problem on my 77 2.7s. First time I drove the car after complete rebuilding engine and cis. Runs smooth… but… stumbles every time between 1800-2400rpm (all gears) After 3000 it runs smooth again. Only noticable under load, not bench test. Weird. Do you think the problem lies within the CiS ststem?
Sounds like fuel, I would put my gauges on the car with a long hose and tape the gauge to the windshield so I can see what the fuel pressure is doing when the problem is occurring.
Kurt
@@klassikats problem solved. Turned out to be indeed fuel related. Combination of leaking WUR diaphragm (so no enrichment on throttle opening) and a (much) too rich mixture. Leaning out the mixture with half a turn solved the issue. Feels great after 4 evenings of hunting the problem 😎. Thanks for sharing the knowledge Kurt 💪🙏
Can you help please I have a 79 911sc 3.0l we are following the video carefully, we have checked the control pressure then closed the tap for system pressure which is at 4.9 bar but when we open the tap again the pressure will not drop back down to control pressure, any ideas.
Thanks ian
Barring any issues with your testing set up it usually indicates a bad warm up regulator.
Is the car running okay?
Kurt
@@klassikats thank you for the quick reply. The car runs okay stationary but under load it pops and bangs and is very hesitant to accelerate. I have just ordered a WUR rebuild kit from Germany so hopefully that will sort it. I will let you know.
Thanks for the videos they just so much help.
kurt, Do you use any thread sealants or lubricants on the fittings,and is it possible to test and access the cold start valve on a 1987 930? Thankyou, Victor
No sealants of lubricants are required. Yes you can access and test the cold start injector in the car. It's a little tough to get to but not impossible.
Kurt
thank you @@klassikats
Whats gonna cause mine to hunt heavily in morning for about 15-20sec
It can be a lot of things including the following items; warm-up regulator out of specifications, air slide not functioning or set correctly, ignition timing incorrect, valves too tight or loose, fuel mixtures incorrect, sensor plate height too high or low, or fuel pressures incorrect. You just need to start at the beginning and work through the system piece by piece.
Could you link where you got that test light?
Alex, The link is in the description, but here it is amzn.to/3y2ZSUz
Thanks
Kurt
CIS is the best system vs a computer with stored data to control. Computer - quantum. CIS - analog.
when working correctly the CIS injection system is pretty reliable and long lasting system.
Kurt
Where are you located ?
Flagstaff, AZ
Pretty good job all in all, very informative. My understanding is that there are adjustments that can be made on the fuel distributor for each independent injector, which perhaps you could have remedied the cylinder #1 low injector flow. Been tuning my 930 for years and it's always good to have a refresher course. Diagnostics can be challenging...isolating and testing each system independently as you've demonstrated is the key.
The flow adjustment on this particular fuel distributor is adjusted using shims under the port spring inside the fuel head. The 3.0L engines used a fuel distributor that had external adjustable springs. However, this is to adjust for slight differences in flow inside the fuel distributor and should not be used to adjust for a poor-flowing injector.
Kurt
@@klassikats thanks for the clarification. Of course my 3.3L engine would have a different distributor. To your point, slight adjustments/fine tuning only, not as a remedy for overall poor flowing issues. I appreciate the knowledge you're sharing.
This is great! Thank you!
You're very welcome!