Mercedes Ke-Jetronic - CO screw adjustment the proper way

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#fixyourmercedes##mercedeskejetronic ##coscrewadjustment#
Adjusting mixture screw proper way. Answer on many questions
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What am I talking about?
My topic is the KE-Jetronic injection system which I try to demystify as much as I can.
For all of you to understand the system in brief - Developed in 1973 and being mounted into cars up to 1993 as it went in history. But why these to letters!?(KE) K(from German "kontinuierlich" meaning continuos, without interruption) the MECHANICAL injection system on which the fuel starts flowing from the fuel tank sucked by the FUEL PUMP and delivered to the FUEL DISTRIBUTOR which sends fuel to the INJECTORS while the majority of it flows through the FUEL PRESSURE REGULATOR through its return line back to the fuel tank again. The letter E(electronic) has to mark the electronic sensors (the developement starting from early eighties) which had to inform the ECU about the current state of the engine so that the ECU(Electronic Control Unit) then could create current signal in mAmp(miliampers) and send it to four crucial components for the system - the EHA(the electro-hydraulic actuator,a unit consisting of a magnet, an electromagnet and a baffle plate) which had to fine tune the engine in each of its phases, the ICV(the idle control valve), the unit which was predicted for the engines perfect idle, the X11(the diagnostic socket) where the duty cycle(the ideal mixture) was adjusted and the X11/4(the code reader) - the socket which from any codes were read if present using an OBD1 scanner.
An extraordinary injection system which could be fully repaired in your own garage using a multimeter and a pressure gauge only for its fine tuning, together with some common tools.
"Happy Mercedesing"

[@mercedeske]

Dear viewers, I must stress that this adjustment is done only in order to check the last mechanical component on the system(the last on my list of things to do on the system). Under these conditions every car must start(1.9mm free play). This is no fine tuning. Every form of a fine tuning is done using multimeters, an ampmeter using exact nominal values as reference like for example the current on the EHA, voltage on the lambda probe, on the potentiometer, a multimeter measuring RPM. But, in order to achieve that - your sensors must be good working and especially for the duty cycle - the potentiometer, the lambda probe and the EHA.

[@doca8792]

I can’t even tell you how much I appreciate this video. So frustrated last two days. I could not go to sleep until I tuned my 190e 2.3-16. I watched this, went to garage, followed your instructions, 10:30 clock at night, the car was driving like it was angry at the world, screaming like it never had before. Now I can sleep. Thank you!

[@mercedeske]

Glad to hear that. Happy Mercedesing 😃 Just enjoying your ride.🍀🍀🍀

[@doca8792]

This man knows his stuff. I was putting Allen key and turning and turning until my wife wanted to leave me because she said “all this work you’re doing and your car still not running right? Just stay in the garage!” No other video showed that little detail, not even my mechanic.

[@mercedeske]

Thanks a lot, pal. I just hope that now with this video I made your wife a little less jealous so you can dedicate yourself more to her than to a car.

[@cengizayten3456]

Hi, I try it to adjust as your explanation. (press and turn it clockwise or reverse) but it newer catch any where for both direction. If the screw broken, what can I do? Thanks for to all your videos.

[@mercedeske]

If nothing happens try it this way. If you are sure that the engine doesn't react by turning the screw in any direction. Greetings kzbin.info/www/bejne/bXXTZp-HgMiMaM0

[@cengizayten3456]

@@mercedeske Thanks and regards.

[@stjornufrostehfvhjrj6264]

Thank you very much for great videos. Had serious problems adjusting fuel system in my 560 SEC. Good luck and keep on your good work. Greetings from Iceland. Fridrik Hagalin

[@mercedeske]

Hi and thank you as well, glad to help and just enjoy your ride. Happy Mercedesing!🍀🍀🍀 Three times for luck and for a long long lasting smile on your face while driving your 560 SEC

[@r3FMusic]

Thanks for video. 1.9mm reference point is ok... But after adjusting 1.9mm the car doesn't start at all. In this case, Lmm poti volt is not read. The Lmm pot needs to be unscrewed and set to 0.70 volts, right? Thank you so much for explaining. we make you tired a lot but we novices will be masters one day :p

[@mercedeske]

I'm glad to help. More than 1.9mm - too much air for the start point. You are right about the poti. My pleasure to help you. I see you made your car good running and you have learned a lot and I am glad for you. If you continue this way you are going to become a good master for KE.

[@gekae24]

How do you remove the security ball to make the fuel adjustment?

[@mercedeske]

@@gekae24 If it's never been removed don't do it.

[@cav4290]

Hello, can you make a short video con how to adjust the CO screw on K-Jetronic?

[@mercedeske]

Ok, I will. In essence, that screw should never have to be adjusted. Once factory adjusted it will never readjust from itself. Only in case someone doesn't know about that. But, thanks, you have me a great idea for the video!

[@cav4290]

@@mercedeske Thank you! I have recently completely rebuilt my metering head (replaced all o-rings and the diaphragm), and re-set the adjustment screws at each port (all are within 3% of the correct flow rates). I do not know if the previous owner touched the CO screws, this is why I want to adjust it myself. Is there anyway I can contact you directly? I do not have a CO meter, which is how it should be done, but perhaps you have another method. Thanks!

[@mercedeske]

I made the video. I need to do something on my car and then I will start editing it.

[@cav4290]

@@mercedeske Thank you very much! How can I contact you directly?

[@mercedeske]

Send me the message on the fb group or on Instagram. How ever you decide.

[@jkhan856]

Thanks!

[@mercedeske]

My pleasure 😊

[@cwmoser]

I had set the Duty Cycle such that when the Engine warms up it varies around 50%, and I check that there was not much play with the air plate. My 1986 560SL runs great this way. So, I watched your video and adjusted the mixture screw to get the air plate to have 1.9mm play. Now my 560SL is hard to start and it idles rough. Don't like this. Finally, I went back and adjusted to 50-50 duty cycle the way I had it and the car runs great and instantly starts back up. With 1.9mm play the Duty Cycle on my meter is no where near 50-50 duty cycle. When I adjust the screw to get 50-50 duty cycle I can see the duty cycle varying around 50 and I guess its the ECU reading the O2 sensor and commanding the EHA to vary the air fuel mixture. Does this indicate that there is something wrong with my 560SL? It drives and accelerates smoothly and powerfully.

[@mercedeske]

If it does, leave it that way!

[@cwmoser]

@@mercedeske I concur, sometimes we have to use "common sense" 🙂 Hey, I do enjoy your videos - they are very informative.

[@mercedeske]

@@cwmoserThanks, glad to hear that. Happy Mercedesing 😃 😊 😉

[@armandomartinsanchez3014]

Thanks Ivica, but i don’t understand very well the free distanc

[@mercedeske]

It must be present.

[@Nich1919]

The ideal distance is 23.5mm for my 230e 1987 ? Thanks for video

[@mercedeske]

That's something you will have to check with the multimeter.

[@oldietolfree1632]

hi, after fitting a reconditioned distributor my mechanic has no fuel coming into it, am i correct to say without the 1.9mm of free play in the pressure plate, that there will be no fuel unless this measurement is correct?

[@mercedeske]

It has nothing to do with fuel flow in general. It has to do with the quality of the mixture.

[@krh007]

Just watched this video and notice you have not re-set your airplate to correct resting position before doing any other settings. Your airplate appears to be resting too high. The bottom edge of the plate needs to be dead level with bevel lip edge (before it cones out when viewing from underneath ) Reset the stopper plate by tapping down on the press fit shaft from above with a punch to lower the stopper plate. Then you can set your 1.9mm free play of the airplate (before it starts to push the FD metering plunger up) Once you have your engine at correct warm idle you are going to have to re-set your potentiometer to 0.7V before doing any other adjustments

[@qwik469]

Can you please help me diagnose my 92 300ce. I have thrown a voltage regulator, ovp, new cpus, plugs, bosch rotor, new cap and wires, fuel filters, fuel pump, fuel system cleaners and even new fuses. Car runs better every time I do something. The car itself has 81k on the clock and when I purchased the car last nov (22) it had expired tags from 2012. With all of this I still encounter a rough idle at times, the car wants to hold shifts till 3500rpm (if I lift foot it will upshift), but most annoying is the ASR light will not come off. Please help with my next step..... Thanks Jay

[@mercedeske]

Hi. Are those miles or kilometers? For now I would advise you to replace the potentiometer and the o2 sensor. As for the ASR light on, I believe it's up to the electronic accelerator, I'm not quite sure.

[@cisco7770]

Salve E complimenti possiedo una w124 200E il motore quanto e Caldo stenta nel Partire..... A Freddo e perfetto.... Cosa può Essere grazie.

[@mercedeske]

Grazie. Hai controllato l'accumulatore di pressione e sostituito gli iniettori?Saluti

[@cisco7770]

@@mercedeske e quale Sarebbe l accumulatore... Grazieeee mille 😘.

[@kaitlinstierwalt7570]

My system does not have an EHA or potentiometer attached to the side of the distributor.

[@mercedeske]

If the screw was never readjusted you never have to do it. Because on K-jetronic it is very hard to adjust the mixture the right way if readjusted. The only way would be with a gas analyzer.

[@kaitlinstierwalt7570]

@@mercedeske My screw does nothing when you do adjust it. If I pull it all the way out, the car still runs. I will do the Gas analyzer test next. Thank you sir.

[@kamila2356_]

Hey Man i have a 1985 190e 2.0 and i want to get the mixture right when i put my Multimeter into X11 port 2 and 3 and read duty cycle i dont get any reading at all and when i change to voltage and do duty cycle formula i keep getting 50 even if i change mixture... what does this mean?!?!?!

[@mercedeske]

Have you replaced the lambda probe?

[@kamila2356_]

@@mercedeske Iam going to do this and get back to you I have done it once before but i didnt rewire very well

[@georgesand4629]

Which way should I turn the screw if it’s hard to start during a cold start?

[@mercedeske]

This adjustment is done for the mixture in general and not for cold or warm start. If you are not sure about the mixture and you readjusted it so that the car won't start then unscrew one of the lines from the distributor to the injectors, bridge the contacts 87 and 30 so that the pump can work constantly(engine OFF) then start turning the mixture screw clockwise until you se fuel coming out of the port. As you do STOP and turn the screw half of a turn counterclokwise. Under these conitions the car should start and then wait until it warms up to make fine adjustments

[@jeanjeanlebelge9263]

Bonjour ivica je viens de voir que j’ai une fuite d’essence au niveau du piston du distributeur pourtant tout les joint sont neuf car je l’es avais changé car j’avais déjà une odeur d’essence dans le débitmètre est ce que le piston peut être usé ? As-tu déjà vu ou entendu cela

[@mercedeske]

Bonjour Jean. Cela peut arriver si la bague d'étanchéité est mauvaise. C'est l'anneau sur lequel repose le piston. Ce joint doit être comme un cône et non un joint torique ordinaire. J'ai acheté le kit chez les Allemands, TS-Technik, et ils fournissent un joint torique ordinaire au lieu d'un joint d'étanchéité, j'ai donc dû en acheter un chez le concessionnaire Mercedes. J'espère que cela résoudra votre problème. L'autre source d'une fuite de gaz peut être si le manchon du piston n'est pas réglé sur le bon espacement, si le manchon est trop vissé. Salutations

[@jeanjeanlebelge9263]

@@mercedeske ici en France il n’est plus possible de trouver ce joint malheureusement Mercedes ne veut plus vendre de pièces c’est la merde

[@mercedeske]

@@jeanjeanlebelge9263 Jean. www.ebay.com/itm/222446844499?epid=14016942138&hash=item33cadd7a53:g:hyoAAOSwuLZY0ORz&amdata=enc%3AAQAHAAAAwNQ%2FGnj7JQZw4Ohr2GXA6btOPGPQ2XbyJ%2Bd5Phx6qakz8jHiH7f98mkEu7XIEpu9SDr0PliUBURzG9LGb3a0G5O4k3GOL%2F%2F1%2FB9J5PuFsQG4wsf7INCd6RnX%2FuRi692%2FvGiEIGlPREpVktD60iH0kodNrNKKJPSrYX0dzCG3c04j7e11f2%2Bb5jWYV%2BGvYmIY8zbPk56fok4d3hhRZMMZwJYN2hX3GmbVtX7TQjIwd45dbFxqFx%2F2qET6Wwpnh8%2FUZQ%3D%3D%7Ctkp%3ABk9SR7Tjze3lYQ

[@jeanjeanlebelge9263]

C’est sur ce site que le joint est ok

[@mercedeske]

This one is okay.

[@ivanclaudiumihai8337]

Good evening my 300 SE from 1987 start for about 5-7 seconds and stops.I changed the hoses the idle valve and the pression regulater...any ideas? Thanks

[@mercedeske]

Good evening. Yes - the potentiometer, the lambda, the injectors. Have you replaced the potentiometer? That's for the beginning.

[@marceldumoulin3223]

Hello, Are the values of the dosing plate the same on all models? Ke-Jetronic 5.2 on a M104.980. When you set your plate this way, you also set the CO, right?

[@mercedeske]

Yes, but as I have already mentioned it in the description of the video, this is just a starting value. If you leave your car just like that you will have a shaky engine. All fine adjustments are then being achieved either at the eha or X11. And yes, you set the CO.

[@marceldumoulin3223]

@@mercedeske Ok and thank you! Sometimes it's hard to understand everything because it's so badly translated! I am Belgian and speak French. Your videos are great and I have to take the time to watch them all. I know a lot about the Ke-Jetronic but here and in France, very few people know how to use the X11 plug. Personally, I do like this: Selector on P, idle and engine 85°C : U 2&3 : 7V U battery : 14,2V 7V : 14,2V x 100= 49,29 100-49,29= 50,71 % Duty cycle. I check with tester and the Duty cycle oscillates from 48 to 53% Normal, the fluctuation represents the image of the activity of the Lambda probe. I will make tests proceeding in your way. Thanks for sharing! Translated with www.DeepL.com/Translator (free version)

[@mercedeske]

@@marceldumoulin3223 Hi again, 👋🏻 you have great readings, don't readjust anything else. Thanks for following my content and Happy Mercedesing 😊 😃 👍🏻🍀

[@marceldumoulin3223]

@@mercedeske Yes, you are right. Have a nice Sunday!

[@gastroalchemy4499]

what is the correct CO reading to tell if the tuning is optimal

[@mercedeske]

If you have a KAT car then it's in general the fluctuation on the EHA between -3 and 0 mAmps once the engine reaches operating temperature.

[@gastroalchemy4499]

Thanks, i meant the corbin monoxide reading from the exhaust. Instead of the duty cycle, some mechanics would do a CO (carbon monoxide) reading at the exhaust for tuning. That's why it's called CO tuning. I wanted to know what is the CO reading.

[@mercedeske]

@@gastroalchemy4499 It should be 1-2%

[@audiovintagefr]

11:01 : you scared me :) !

[@mercedeske]

Haaaaahahahahahahahaaa 🤣🤣🤣🤣🤣

[@ldewitte028]

Hello, I smell fuel when driving. In wich way must I turn the scew?

[@mercedeske]

Hello. At first - which parts have you replaced on the system?(injectors, lambda, potentiometer, fuel pressure regulator, etc.)

[@ldewitte028]

@@mercedeske hello, nothing has been replaced.Just I remember that once a friend mechanic turn the the crew to right in order to enricher the mixture cause I wanted more power. But from month now I smell fuel in the exhaust fumes…

[@mercedeske]

@@ldewitte028 Well, then until you get fluctuating resistance on the X11 between 6.6-7.33V

[@bikeman123]

You never mention the air screw adjustment. People fiddle with the mixture screw when they should be using the air screw to set the idle speed.

[@mercedeske]

I did mention it. Look, there are three types of idle control valves. The one you are talking about is the second one, the one with 3 contacts. There you can adjust the idle manually. On the last generation of the icv it's not possible because the ecu does that. In fact there is a place where to turn the screw but I wouldn't recommend anyone to do that because that's adjusted as it should be in case the ecu fails so that the icv can work as much as possible. On V8 engines it is possible to be done manually but only on V8 engines.

[@autoensemblemedia7663]

Where can you adjust it on the v8 560SEL?

[@mercedeske]

It is done only if you have no vacuum leaks and if the ICV is flushed. IF you still have vacuum leaks then it can be done but this information is not for free.

[@georgesand4629]

I fucked up and lost the original spot of hex screw. It will not cold start now. What should I do?

[@mercedeske]

Remove the fuel pump relay, bridge the contacts 87&30 with a wire, remove a metal hose. Turn the ignition on and start enriching the mixture(turning the 3mm allen clockwise) until you see fuel coming out of the port where you removed the hose. As the fuel starts coming out stop and turn the allen screw for a half a turn counterclockwise.

[@georgesand4629]

The metal hose on the fuel distributor?

[@mercedeske]

Yes

[@georgesand4629]

Hi it’s me again. I was having the duty cycle with cold start issues. Maybe I should leave the removing metal hose alone for now.

[@mohdsanimustafar3540]

Ahaha this is funny