Mercedes Ke-Jetronic - Some misunderstandings on CO/mixture screw and its adjustment in real time

A video on how adjust the CO/mixture screw in real time
#fixyourmercedes##kejetronic##mixturescrew#
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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"

[@markb9170]

I have been using an Air/ Fuel gauge with a wide band this seems to work real time. Amazing how much a small adjustment changes the A/F ratio.

[@mercedeske]

Exactly. An extremely precise unit!

[@ceasarspalace]

I watched the whole video 👍

[@mercedeske]

👍🏻🍀🍀🍀😃💪🏻👌🏻

[@r3FMusic]

There is no more problematic Ke-Jetronic in the world. =) Many thanks for the detailed explanation.

[@mercedeske]

My pleasure and everything for my subscribers and dear people that value my work and effort!!! Happy Mercedesing

[@hadinova]

Thank you, I applied the standards to my car and it is working fine👍💯⭐⭐⭐⭐⭐

[@mercedeske]

😃😃😃I am glad to hear that 😊👍👍👍

[@khinthant952]

Last week mine one was fixed from your previous video clip that I watched. Many thanks for your BIG HEART! Also thank for the other video(ufo and sub) clip that helped me a lot because I've found out my vacuum line was blocked too.

[@mercedeske]

Thanks for these nice words! Happy Mercedesing!

[@john-lh1pr]

Thanks for you excellent video. It helped me a lot.

[@mercedeske]

My pleasure. Happy Mercedesing 😃 😊 🍀

[@dannoi]

Great video as always ! ya people skip through, but thats people for you )) always in a rush, but you cant fix a kjet in a rush lol

[@mercedeske]

Thanks. Exactly!!!

[@issamalmousa76]

Actually i would like to thank you for your achievements about the ke-jetronic. Regarding to this video i have a mercedes W124 260e i have tried many times to adjust the air flow sensor as per your explained in the video but don't get the same numbers. Are this numbers by the caliper measure just for M102 or there is different measures for M103. if not , please where is problem in my car. Thanks

[@mercedeske]

Hello and thanks. You will have to do it with the caliper as in my video and per my instructions. If the car starts running rough though just set the mixture to fluctuate 6.6-7.3V on X11.

[@issamalmousa76]

@@mercedeske thanks for your kind reply sir, But could you please clear to me how adjust the mixture to fluctuate 6.6-7.3V on X11 I don't understand 😞. Thanks

[@mercedeske]

@@issamalmousa76 Set your multimeter to DC voltage, stick the ground into pin2 on your X11, positive goes into pin3. Once the car reaches the operating temperature the voltage will start fluctuating. Clockwise you increase the voltage and therefore enrich the mixture. If there is no fluctuation then replace the lambda probe.

[@issamalmousa76]

@@mercedeske thank you very much,, i will do my best my friend

[@issamalmousa76]

@@mercedeske hi Mr. Evey. I would like to draw your attention that i don't have lambda in my car system, so can i proceed with the procedure step by step as your explained in the video. Appreciated Thanks a lot.

[@makavelibenzze]

yes mine is running at its best thanks to youu! thank you my friend.....but my C/O screw seems to run out off specs when i drove the car too fast. Fast like 170 KPH....not in highway but in a bit bumpy roads....i have to get back home and set the C/O screw back it again, after it will run fine with a good startup like mew. Why its like that? is it too old for that? Lol

[@mercedeske]

Thanks my friend. For further fine adjustments you will need to connect the multimeter on the x11 round socket. Look if you achieve the fluctuation of 5% around 50% and this goes not just for the idle, you must get that fluctuation also when you accelerate to 2000rpm. In order to achieve this you will have to turn the screw in tiny movements - I always say if you have an analog watch look at it and turn the screw for as much as "2 seconds" and then let the car run for 10 seconds(the ECU has to learn then). Then check the potentiometer if it shows still 0.7V, that's important also. I still can't do the video on duty cycle, I still have to deal with some minor issues on my car. Many greetings and Happy Mercedesing

[@makavelibenzze]

@@mercedeske okey thanks for the knowledge....but i dont have the proper tools yet. Anyway, do you know why the ICV hoses have a pointy joint with a small hole in the middle, that connects to the intake filter box? what is it for.. Iv close that small hole, the idle seems better..as i was searching for vacuum leaks.

[@mercedeske]

@@makavelibenzze You would have to send me the video.

[@hendragunawan-up7kd]

Hello mr.ivica I have some Q are these 1.9mm clearence of plunger can be done on m103 w124 300E ?

[@mercedeske]

Hello, yes it can be done but don't do it if you don't have to.

[@sKraat528]

Regarding the factory 'plug' that covers this adjustment screw- What is safest way to remove the plug? After I replace potentiometer and injectors, and then make sure everything else checks out, I understand that I 'may' need to adjust this to get the duty cycle to tolerable value.

[@mercedeske]

You will have to plug the multimeter on X11 and measure % If you get the fluctuation around 50, everything is okay you don't have to adjust anything. Or you can do it on the EHA and measure mAmps. With engine at 80 you will have to get the fluctuation around 0(tending to negative)mAmps on idle. If not, then you will have to readjust the mixture screw.

[@sKraat528]

@@mercedeske Okay thanks. I will let you know how it turns out after new injectors, proper plugs, and potentiometer. Maybe no adjustments will be needed, that would be cool!

[@mercedeske]

Yeah!!!👍🏻👋🏻🤞🏻

[@sKraat528]

@@mercedeske OK installed new injectors and proper (non resistor) spark plugs, and it made HUGE difference, no more shake on idle, starts faster, seems to run MUCH better. However, the check engine light is on, and holding the small diagnostic button for two seconds, the LED gives me 4 flashes. This is potentiometer?

[@mercedeske]

I guess so. There is in the table I gave. I think it's the potentiometer.

[@audiovintagefr]

Hello, Thanks for giving us the keys to well drive our olds Mercedes :) I just done the adjustment on my 230ce 1991 (kat), 260.000km. There was 2.8mm before adjusting and now 1.9mm (+ or minus 2mm :) ) I cannot say that it is better than before, bu it's not worst :). I have also a question on the duty cycle measure. On my car, cold or hot, I have 49.96% at start-up. Then when the motor goes to 750/800rpm the duty cycle goes between 22 and 28%, fast oscillating (more to 28% than 22%). If i take some rpm, it will bounce at 49.96% but rapidely goes back to 22% to 28%. Is it normal ? I know that there is difference between non catalyzed cars and catalyzed car like mine. The O2 sensor, the coolant temperature sensor, air sensor, sparks plugs, air filter, all fluids are new. The cut power switch at the end of accelerator cable is ok. The car is not very soft when driving and there is some very little hicups when deccelarating or with a little power on the gaz pedal. No problem with max power :) Sometimes (not always) when cold but also when the motor is hot, the start-up is not very good, rpm is oscillating (below 1000rpm). If you have ideas, I take them :) Thanks again !

[@mercedeske]

Hello and thanks for your kind words. Concerning the car - check the TPS if it recognizes both positions(you have the video on my channel). According to the table it look like your TPS is not in order(the full throttle). All these numbers count when the engine is warm. Check also if the ecu shows any codes(rectangular little box next to the battery), you will need an OBD1 scanner for this, don't do it with a wire like me ;-) If you get a single pulse, then it means that there are no codes stored in the ECU. 22-28% means rich mixture. Try moving the co screw counterclockwise, but let it be for an eight of the inch and wait for about 10sec. afterwards give a throttle blip. If the number doesn't raise in %, then there is a code stored in the ECU. The mixture you can check on the lambda as well. As the car is warm stick out the jack of the lambda and measure the voltage. If the voltage is 0.8-1V then you have a rich mixture for sure. There, that's what I can say for now. Hope you solve your issue, happy Mercedesing

[@audiovintagefr]

@@mercedeske Thanks. Just tested the TPS with the help of your video (perfect as usual :) ) and the TPS is working fine. I also tested the voltage on the lambda and I have 0.8v. The duty cycle measurement indicate plus or minus 20% (between 13% and 26% approximatively). Unscrewing the CO screw seems to change anything on the duty cycle reading. I'm going to constuct the scan and test.

[@mercedeske]

@@audiovintagefr There, you have a rich mixture. Try unscrewing the CO screw but don't go for much, always an eight of an inch. If no improvements, then don't go for too much.

[@audiovintagefr]

@@mercedeske Juste done the obd and used it : 1 blink so no problem here. Action on the Co screw (unscrew) change nothing in the duty cycle reading, even with 5 turn of screw :(

[@mercedeske]

Is your potentiometer ok? Do you read 0.7V?

[@arvandikaondi5926]

Can i treat my m103 engine like this?

[@mercedeske]

What did you mean exactly?I didn't understand quite the question.🙂

[@MrTaipeh1]

When I push the plate down I dont really feel resistance after the 1,9mm gap. Is this normal?

[@mercedeske]

No, it isn't.

[@MrTaipeh1]

@@mercedeske What can be wrong with it? I dont really know what to do any more. Everything I try to fix gets worse. I really need help

[@mercedeske]

@@MrTaipeh1 You can have either too much play or none. As you deflect the sensor plate you just feel it moving downwards. In order to create that play you must turn the mixture screw counterclockwise. Watch this video where I clearly show how it looks like when there is no play at all and when there is a play. Watch the video from 4:25 I hope you will see the difference when I turn the screw all the way clockwise and counterclockwise. kzbin.info/www/bejne/ipnSkqeDobCHac0

[@MrTaipeh1]

I watched the Video 4 times. But when I put the sensor plate slowly down. ( ignition off) I dont really feel the resistance off the plunger as you say in you Video. I have try this out, When I bridge the fuel pump, there is resistance in the Plate but I dont want to run the fuel pump longer then couple of seconds. Is something wrong there? Or im i just stupid? I will make a video tommorow and upload it on my Channel. Youre the Best 😄

[@mercedeske]

@@MrTaipeh1 😃👍🏻Thanks! Of course you are not stupid! When you bridge the pump the car builds pressure. I forgot which car you have. For example m103 engines have no spring in the barrel of the plunger, they rely on the pressure.

[@سلیمانبخشیپور]

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