[fahimyh25]

Who removed the temper resistant ball that sits above the idle mixture screw??? If it wasn't you, then somebody else before you was already messing with the car.

Yes it seems because I didnt remove anything in fact I didnt know there was a such thing

 

[isthenew]

Who removed the temper resistant ball that sits above the idle mixture screw??? If it wasn't you, then somebody else before you was already messing with the car.

This is a really valid point. And it lends even more strength to checking the fuel pressures.

In my car, in those pictures I posted here, you can see cuts in my tower where some previous person removed the ball. That’s why I jumped into my system. Which I now regret. Because I reset most of what I changed.

…With the airflow plate there are two adjustments. The first is a gross adjustment via that pin I circled in the my pictures. At rest, the air flow plate is to rest with the top of its plate at the top of the cylinder. You’ll note where the air flow plate sits, it’s inside (from bottom up) a cylinder, then a cone, and then a larger cone. The height in the cylinder is adjusted by the pin.

After that, you jump the fuel pressure relay (pins 7 and 8) building fuel pressure. You then press the plate. You should have 1-3mm free play and then pressure. This free play is adjusted via the 3mm tower.

After that, you fine tune with duty cycle.

Here’s my thread of errors to learn from.

M103 Air meter

Hello All, This regards my 1989 300SE with 234k miles. Today I tested my engine vacuum system for leaks, and I got to looking at my air meter assembly. I have the bar that goes across it, and the plastic piece on the bar. And I have the piece that moves up and down, and that has a nut on...

www.benzworld.org

 

[isthenew]

You also should test your air flow potentiometer.

 

[fahimyh25]

You also should test your air flow potentiometer.

Ok thanks again

 

[humblejoe]

Not all towers were blocked off. At some.point they made them serviceable again

 

[emirtal]

Perhaps this could help you chase down the issue or at least help give you a checklist of items to look at and verify: M103 Issue Diagnosis

My advice is to avoid any adjustments or any sort of "tuning" until you verify function of all of the sensors, components and mechanical side of the engine. Start with the simple stuff first. Is airflow ok (aka vacuum leaks)? Is gas delivery ok? Do I have spark? etc.. More often than not, people replace items thinking they're bad and quickly end up going down a very expensive wild goose chase. Make sure to take notes of what you've done to both stay organized and also help give you clues.

Like many other users mentioned, props to you for tackling this head-on. It can seem very daunting at first, but keep at it!

 

[fahimyh25]

Perhaps this could help you chase down the issue or at least help give you a checklist of items to look at and verify: M103 Issue Diagnosis

My advice is to avoid any adjustments or any sort of "tuning" until you verify function of all of the sensors, components and mechanical side of the engine. Start with the simple stuff first. Is airflow ok (aka vacuum leaks)? Is gas delivery ok? Do I have spark? etc.. More often than not, people replace items thinking they're bad and quickly end up going down a very expensive wild goose chase. Make sure to take notes of what you've done to both stay organized and also help give you clues.

Like many other users mentioned, props to you for tackling this head-on. It can seem very daunting at first, but keep at it!

Ok thanks alot for the advice

 

[fahimyh25]

Right now it's dark so I will not be working on it but my plan was to test the potentiometer and work on the plate because it was wrong, anything else I should do tomorrow

 

[sbaert]

I think you should focus on fuel supply and fuel pressures first and foremost.

First off, replace the 3 fuel filters (tank, fuel filter, fuel distributor). Proper pressures cannot be gotten with blocked filters.

Then take the 3 vital pressure readings (system, control, rest), followed by doing the fuel pump volume test. Also suggest you do the volume test from each pump since you have 2 fuel pumps.

As I stated before, KE Jetronic is a purely mechanical system based on pressure. Without the proper pressure and/or volume, it will never run right.

Don't forget that the fuel pumps are a wear and tear item, and based on the age of the cars, most are well beyond their sell by date. A very EZ quick check of the pumps is to listen when the ignition is turned on (key in position 2). You should hear a brief psssh noise as the pumps pressurize the fuel system. If the noise lasts more than a couple of seconds then there is a issue. Ditto if no noise can be heard.

 

[fahimyh25]

I think you should focus on fuel supply and fuel pressures first and foremost.

First off, replace the 3 fuel filters (tank, fuel filter, fuel distributor). Proper pressures cannot be gotten with blocked filters.

Then take the 3 vital pressure readings (system, control, rest), followed by doing the fuel pump volume test. Also suggest you do the volume test from each pump since you have 2 fuel pumps.

As I stated before, KE Jetronic is a purely mechanical system based on pressure. Without the proper pressure and/or volume, it will never run right.

Don't forget that the fuel pumps are a wear and tear item, and based on the age of the cars, most are well beyond their sell by date. A very EZ quick check of the pumps is to listen when the ignition is turned on (key in position 2). You should hear a brief psssh noise as the pumps pressurize the fuel system. If the noise lasts more than a couple of seconds then there is a issue. Ditto if no noise can be heard.

ok thank you very much, and also 1986 has only 1 fuel pump or just mine im not sure

 

[emirtal]

I think you should focus on fuel supply and fuel pressures first and foremost.

First off, replace the 3 fuel filters (tank, fuel filter, fuel distributor). Proper pressures cannot be gotten with blocked filters.

Then take the 3 vital pressure readings (system, control, rest), followed by doing the fuel pump volume test. Also suggest you do the volume test from each pump since you have 2 fuel pumps.

As I stated before, KE Jetronic is a purely mechanical system based on pressure. Without the proper pressure and/or volume, it will never run right.

Don't forget that the fuel pumps are a wear and tear item, and based on the age of the cars, most are well beyond their sell by date. A very EZ quick check of the pumps is to listen when the ignition is turned on (key in position 2). You should hear a brief psssh noise as the pumps pressurize the fuel system. If the noise lasts more than a couple of seconds then there is a issue. Ditto if no noise can be heard.

I wouldn't bother replacing the filters off the bat. Doing a fuel pressure test can verify if you have a block or reduced flow. Reason being, I don't want the OP throwing down money left and right without determining the issue off the bat. Also, his fuel pump should be working as the car was running. Dead pump = no start or run.

 

[emirtal]

Ok thanks alot for the advice

For testing the fuel you'll need to get your hands on a CIS fuel pressure test kit, or construct your own. Do you have access to a fuel pressure gauge test kit/or are able to purchase one? If not, lets start with looking at other things which are easier to measure. I agree with others, the fuel balance on these cars is critical, but there are much easier things to check..

I would suggest making is a smoke machine. You can DIY one pretty easily for around $20. There are plenty videos demonstrating how to do this. As others mentioned, any vacuum leaks will cause chaos on the system. My advice, start with checking this first. The car does not need to run for this.

OP, again.. I strongly advise you to visit the post I sent you and start checking off each component for operation or you will be chasing your tail endlessly. I have done the same. As for the adjustments made on the tower.. it can be reset to a rough position and calibrated from there.. However without a multimeter, you will not be able to do this correctly. Not to mention, you really need to check off all the other parts of the system before even thinking of doing this.

One interesting thing, you mentioned that you had to depress the plate to get it running. Depressing the AFM plate will result in a richer mixture being applied. If the car did not want to run without having some sort of enrichment, it was running lean. Hint: consider what I suggested above and why the engine might be running lean.

 

[emirtal]

One last suggestion.. Maybe I am a little pedantic.. However, I would avoid revving the car until resolving or at least checking some of the issues. The engine clearly does not have a good mixture and the last thing you want is to be applying higher pressures etc on the engine.

Analogy: You wouldn't want to run a marathon with a sprained ankle. Two reasons, it hurts and you'll cause more damage.

 

[sbaert]

Filters are cheap and cheerful and almost always ignored or forgotten. They are a integral/critical component to the fuel system working per spec. Everything else is going to cost more.

 

[fahimyh25]

One last suggestion.. Maybe I am a little pedantic.. However, I would avoid revving the car until resolving or at least checking some of the issues. The engine clearly does not have a good mixture and the last thing you want is to be applying higher pressures etc on the engine.

Analogy: You wouldn't want to run a marathon with a sprained ankle. Two reasons, it hurts and you'll cause more damage.

Thank you very much you have given me a load of things to do and check 😂, I like it, thank you

 

[plinker17722]

Sbaert . Is there another place that us W124 owners can install an extra fuel filter ?.

 

[sbaert]

The main filter does the bulk of the work, BUT an extra filter can be installed inline at the main feed going to the fuel distributor. However, if you keep up on maintenance (time and mileage wise) this step is not necessary.

 

[Marcel107]

The Filter at the Fuel Distributor (M103) is here

 

[fahimyh25]

You also should test your air flow potentiometer.

@isthenew I tested the potentiometer with a multimeter and it read around 4.50 on each connection, I also was adjusting the adjustment screw and I was making progress she revs much higher now I just have to wait till tomorrow to see if she starts quicker

 

[fahimyh25]

@isthenew or anyone question when I press the air sensor plate down a little bit the car tries to shut off or if I hold it for too long it will shut off, what does it mean? What do I do?