idling problem
Thread Starter
Newbie
Joined: Dec 2025
Posts: 14
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Mercedes 190 E 2,3 8V
[QUOTE=dolucasi;9250449]You are supposed to put something like a latex glove over the intake above the AFM plate. sure, of course Smoke will of course go thru there without it.
The some tester also comes with connectors. plugs etc that are needed. This is why a home made ferry rigged set up is a bad idea.
On the adjustments, please, please please do not touch/adjust anything BEFORE you post it here. I'll have to try and calibrate the pot . I need to bring up the revs to stop it stalling and then I'll post the readings on the duty cycle and EAH. and we can go from there,
Once the vacuum leaks and TPS is back to normal and in original condition with the proper adjustment. We can take the next step. My 2 recommendations are:
x to ge t it
-Do not replace anything
-Do not adjust anything
Before checking on this site. (unless you have a local mechanic who knows this system in detail, but clearly you do not)
The some tester also comes with connectors. plugs etc that are needed. This is why a home made ferry rigged set up is a bad idea.
On the adjustments, please, please please do not touch/adjust anything BEFORE you post it here. I'll have to try and calibrate the pot . I need to bring up the revs to stop it stalling and then I'll post the readings on the duty cycle and EAH. and we can go from there,
Once the vacuum leaks and TPS is back to normal and in original condition with the proper adjustment. We can take the next step. My 2 recommendations are:
x to ge t it
-Do not replace anything
-Do not adjust anything
Before checking on this site. (unless you have a local mechanic who knows this system in detail, but clearly you do not)
MBWorld Fanatic!
Joined: Mar 2016
Posts: 1,369
Likes: 195
From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Only adjust to afm-pot to the designated spec. Do not adjust it to get the car to do something that appears to be "better".
If you are having to do something out of the spec to get it to run "better" something else is wrong with the system, not the AFM-pot.
This is the trap most inexperienced DIY'ers out there fall into. Same goes with the EHA adjustment and the AFM level adjustment.
One can not adjust these things with how the engine seems to run. If everything is adjusted to spec, these cars will run like the first day they left the lot at the dealer.
So adjust it so that the voltage on it is steady and I believe it is something like 0.7V (maybe it was 0.65 +/- 50mV but check that online).
After that we will have to measure various outputs to see what is off. If you have the inclination, you should order the dual fuel pressure gauge as well.
My 2 cents worth ....
If you are having to do something out of the spec to get it to run "better" something else is wrong with the system, not the AFM-pot.
This is the trap most inexperienced DIY'ers out there fall into. Same goes with the EHA adjustment and the AFM level adjustment.
One can not adjust these things with how the engine seems to run. If everything is adjusted to spec, these cars will run like the first day they left the lot at the dealer.
So adjust it so that the voltage on it is steady and I believe it is something like 0.7V (maybe it was 0.65 +/- 50mV but check that online).
After that we will have to measure various outputs to see what is off. If you have the inclination, you should order the dual fuel pressure gauge as well.
My 2 cents worth ....
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
I should've thought of this sooner but you can also google the videos of Pierre Hedary on the K-Jetronic fuel system which is the fuel system your car has. Pierre owns his own repair shop in Titusville, FL that specializes in the Bruno Sacco designed cars including your W201 model. Pierre is well known among MB enthusiasts for his expertise.
You also need to listen to Dolucassi's advise. He's an engineer and he gives really good advise. I think where you got yourself into trouble is by using atter market parts and making adjustments without really determining what the actual problem is. Just my 2 cents.
You also need to listen to Dolucassi's advise. He's an engineer and he gives really good advise. I think where you got yourself into trouble is by using atter market parts and making adjustments without really determining what the actual problem is. Just my 2 cents.
Thread Starter
Newbie
Joined: Dec 2025
Posts: 14
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Mercedes 190 E 2,3 8V
Hello , I just wanted to post that the idling problem has been solved and I hate to admit it but there was I split in the rubber boot under the sensor plate. I didn't pick up on it until a did a smoke test . I missed it the first time around when I did a visual test. There's a lesson lo be learn't, always do a smoke test because spaying inflamables is not 100% accurate or just a visual- . I replaced the ventilation hoses, rubber boot .I also calibrated the Potentiometer , and adjusted the mixture The specs on the EAH and duty cycle are correct and I can honestly say it's running as new.
Thanks for all the post on the matter.
Thanks for all the post on the matter.
MBWorld Fanatic!
Joined: Mar 2016
Posts: 1,369
Likes: 195
From: SF Bay Area, CA
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Congratulations P.Bat. Great to hear!
This is a great reference post. Hope other owners will see it in the future!
Happy motoring!
This is a great reference post. Hope other owners will see it in the future!
Happy motoring!
Last edited by dolucasi; Jan 21, 2026 at 02:47 PM.
MBWorld Fanatic!
Joined: Feb 2020
Posts: 1,995
Likes: 394
1991 190E 2.3
I'm glad the problem has been solved. Sometimes the silliest of things can wind up being the problem. That's why I was always to to retrace my steps when dealing with such a maddening situation. That's what you did and it worked.
