KE-Jetronic Lambda control (duty cycle) adjustment - Page 2 - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #11 of 72 (permalink) Old 06-22-2017, 03:10 PM
Moderator
 
Date registered: Dec 2012
Vehicle: 89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
Location: San Jose, California
Posts: 2,100
Mentioned: 10 Post(s)
Quoted: 547 Post(s)
Send a message via Skype™ to dolucasi
H.D., my Jetronic is running very well at the moment but I would love to have that instrumentation in my astray as well. Much better use of the space.

Simply put, you "must" make more of those (:-))
dolucasi is online now  
Sponsored Links
Advertisement
 
post #12 of 72 (permalink) Old 06-23-2017, 12:57 PM Thread Starter
Outstanding Contributor
 
H.D.'s Avatar
 
Date registered: May 2014
Vehicle: 1988 300CE
Location: Germany
Posts: 1,360
Mentioned: 36 Post(s)
Quoted: 515 Post(s)
(Thread Starter)
Quote:
Originally Posted by dolucasi View Post
... I would love to have that instrumentation in my astray as well. Much better use of the space.
Simply put, you "must" make more of those (:-))
Haha … you would indeed have appreciated it when you had your idle issue several weeks ago. The OVP’s intermittent ICV power supply problem would have leaped to your eye ’at the touch of one of its buttons’ ! ...

I really suggest to consider such a device … provides valuable information (not only) about the KE-Jetronic and speeds up diagnosis immensely … especially in case of intermittent problems.

And when you don’t use it you can switch it off and close the ‘ashtray’ ... however, in the initial period after installation you might find it interesting to keep it open and watch how Lambda control works during driving. …

H.D.
H.D. is offline  
post #13 of 72 (permalink) Old 06-23-2017, 02:34 PM
Moderator
 
Date registered: Dec 2012
Vehicle: 89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
Location: San Jose, California
Posts: 2,100
Mentioned: 10 Post(s)
Quoted: 547 Post(s)
Send a message via Skype™ to dolucasi
Quote:
Originally Posted by H.D. View Post
Haha … you would indeed have appreciated it when you had your idle issue several weeks ago. The OVP’s intermittent ICV power supply problem would have leaped to your eye ’at the touch of one of its buttons’ ! ...

I really suggest to consider such a device … provides valuable information (not only) about the KE-Jetronic and speeds up diagnosis immensely … especially in case of intermittent problems.

And when you don’t use it you can switch it off and close the ‘ashtray’ ... however, in the initial period after installation you might find it interesting to keep it open and watch how Lambda control works during driving. …

H.D.

Precisely H.D.. I could have converged on the answer in a matter of days instead of 3 months!
Please put me on top of the list when you decide to produce them in quantity.

Do you happen to have a circuit diagram and BOM for it? I can also make it but I would hate to re invent the wheel....
dolucasi is online now  
Sponsored Links
Advertisement
 
post #14 of 72 (permalink) Old 06-24-2017, 02:20 PM Thread Starter
Outstanding Contributor
 
H.D.'s Avatar
 
Date registered: May 2014
Vehicle: 1988 300CE
Location: Germany
Posts: 1,360
Mentioned: 36 Post(s)
Quoted: 515 Post(s)
(Thread Starter)
Quote:
Originally Posted by dolucasi View Post
Precisely H.D.. I could have converged on the answer in a matter of days instead of 3 months! ...
… not in a matter of ‘days’ … in a matter of ’seconds’ you would have seen with that device that the OVP’s supply voltage to the ICV was zero volt when the high idle occurred. …


Quote:
Originally Posted by dolucasi View Post
... Please put me on top of the list when you decide to produce them in quantity.
Do you happen to have a circuit diagram and BOM for it? I can also make it but I would hate to re invent the wheel. ...
Haha … my last post sounded a little like advertisement, right? … But I’m not planing to produce it in quantity and offer it for sale.

It‘s not difficult to make … should be done with care though, so that no components (especially ECU) get damaged. ... I think I still have sketches (panel, brackets, circuit diagram) and a BOM somewhere, but I changed the circuitry subsequently (w/o changing the labels on the board).

Since it not only displays the duty cycle, but also provides other information, going into its details would be off-topic in this thread. I‘d rather start an extra thread about it. … But currently I hesitate to do that as well as I currently hesitate to participate in other member’s threads ... because without email notifications from Benzworld (on threads I’m subscribed to and on PMs) it can easily happen that I don’t notice further posts / questions, especially if they‘re a few days old.

I‘m also thinking about extra threads about the very informative (simultaneous) tests I mentioned in post 10 (EHA current, fuel pressure, o2 sensor voltage) when I have more time and when that notification problem is fixed. … I still hope it can be fixed, but unfortunately all efforts and inquiries to BW‘s administration have been unsuccessful so far. …

H.D.
dolucasi likes this.
H.D. is offline  
post #15 of 72 (permalink) Old 08-22-2017, 06:30 AM
Outstanding Contributor
 
Date registered: Jan 2004
Vehicle: '03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
Location: Atlanta, USA
Posts: 4,063
Mentioned: 14 Post(s)
Quoted: 605 Post(s)
The mixture adjustment procedure in this thread was posted in the R129 forum and found to be unworkable for all U.S. cars. It's my guess that as written it won't work for any vehicle powered by the M104 or M119 engine, and that includes some W124 cars. The problem is a fundamental error that makes it impossible to complete the checks which are designed to ensure the accuracy of the duty cycle measurements.

The information in this new post is based upon Mercedes' Startekinfo.com website and may not apply to all cars with M104 and M119 engines.

Quote:
Originally Posted by H.D. View Post
In case of the KE-Jetronic the duty cycle value refers to the square wave voltage’s ‘off’-time.
"Off" refers to low voltage, and that is the convention upon which Mercedes' documentation is based. A way to distinguish whether a duty cycle reading references the signal's time at low voltage or high voltage is to take a measurement with the key on, the engine off, and a coolant temperature below 70 degrees Celsius. Along this line post #2 states:

Quote:
Originally Posted by H.D. View Post
With ignition switched on (engine not running) the duty cycle should be about 70% (California: 85%).
According to Mercedes the duty cycle with a cool engine should be 30%, not 70% -- this fact may be inferred from reading this table. To be clear, closed-throttle duty cycle is 70% for most W124s but is 30% for most if not all cars with M104 or M119 engines.

If a meter displays 70% its reference is wrong, and a simple remedy may be to swap the meter's leads to give a reading of 30%. Otherwise it is necessary to adapt to the incorrect reference by subtracting 100% from all duty cycle readings and then regard the negative result as a positive number. If a duty cycle other than 30 or 70 is displayed by a meter, then the throttle switch or other input is in the wrong state.

Quote:
Originally Posted by H.D. View Post
With ignition switched on (engine not running) the duty cycle should be about 70% (California: 85%).
If you’re using a voltmeter it should read 0.3 * Vp6 (California: 0.15 * Vp6).
If the duty cycle should be 30%, than a voltmeter should read .7 * Vp6.

Quote:
Originally Posted by H.D. View Post
A static (not fluctuating) duty cycle value with the engine running and the o2-sensor at operating temperature, indicates a problem according to the following list...
The list in post #2 is slightly inaccurate for an M119 or M104 engine. A more accurate and detailed reference which includes steps to troubleshoot the problem is found here at Startekinfo.

A closing comment:
Quote:
Originally Posted by H.D. View Post
A duty cycle at idle fluctuating around a mean value of about 47% or a little lower is usually a good choice for an intact KE-Jetronic in my experience.
Steve Brotherton is an engineer with perhaps more experience with Bosch Jetronic injection than anyone on the planet. Over on Peachparts.com he states that his personal preference is to adjust the mixture rich for a 40% duty cycle.
bobterry99 is offline  
post #16 of 72 (permalink) Old 08-22-2017, 08:14 AM Thread Starter
Outstanding Contributor
 
H.D.'s Avatar
 
Date registered: May 2014
Vehicle: 1988 300CE
Location: Germany
Posts: 1,360
Mentioned: 36 Post(s)
Quoted: 515 Post(s)
(Thread Starter)
^^^ Is it just me, or does that sound like this whole duty cycle adjustment procedure doesn’t work on U.S. cars equipped with M104 engine ... ... (Btw, no KE-Jetronic in 124’s equipped with M119 engine).

There’s a reason for what you probably read between that poster's lines … different story …

Maybe someone on the other side of the pond can commend on what he says about the duty cycle value with "ignition on / engine off" on U.S. 124's equipped with M104 engine !?

Regarding somebody else’s duty cycle adjustment preference he mentions ... see what I said in post #2:
Quote:
Originally Posted by H.D. View Post
... A duty cycle at idle fluctuating around a mean value of about 47% or a little lower is usually a good choice for an intact KE-Jetronic in my experience ...
“intact” means “completely in order” … it refers also and especially to the fuel distributor and its parts and its cleanness.

Also see what else I said in that post:
Quote:
Originally Posted by H.D. View Post
... Above target values apply to an intact system (not only CIS) !
Generally problems relevant for the fuel combustion have an influence on the EHA control, hence on the duty cycle. Depending on the problem(s), the most suitable duty cycle could, for instance, be below 30% or above 70% ...
Btw, bobterry99 ... don't forget what I said in the 129 forum about further communication between you and me. ...

H.D.

Last edited by H.D.; 08-22-2017 at 08:32 AM.
H.D. is offline  
post #17 of 72 (permalink) Old 08-22-2017, 10:27 AM
Outstanding Contributor
 
Date registered: Jan 2004
Vehicle: '03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
Location: Atlanta, USA
Posts: 4,063
Mentioned: 14 Post(s)
Quoted: 605 Post(s)
Quote:
Originally Posted by H.D. View Post
Regarding somebody else’s duty cycle adjustment preference he mentions ...
To be clear, there is nothing wrong with adjusting mixture to a duty cycle value that fluctuates around 47%. In fact, M-B states that anything between 30 and 70% is within specification. My cars are set to 50%, but I intend to defer to Steve's 4 decades of experience and adjust them to 40 once I get around to it.

Quote:
Originally Posted by H.D. View Post
Maybe someone on the other side of the pond can commend on what he says about the duty cycle value with "ignition on / engine off" on U.S. 124's equipped with M104 engine !?
I encourage anyone with an M104 or M119 engine to check and report to this thread their findings regardless of location, and for accuracy it may be best to state the voltages on sockets #3 and #6. I spent hours on another forum looking at posts discussing duty cycle and found contradictions and confusion; it is a consequence of having different perspectives on duty cycle.

If a 10 ml glass holds 7 ml of water, then most people would describe the glass as being 70% full. But metaphorically, Mercedes would describe it as being 30% empty. Similarly, if a square-wave diagnostic signal is in a high-voltage state 70% of the time (Steve B. picture, attached), conventionally it is understood to have a duty cycle of 70%; yet Mercedes considers the percentage of time the signal is in its other (low-voltage) state, and to them the duty cycle is 30%.

To get a Mercedes "glass empty" duty cycle measurement using a multimeter that reads duty cycle one typically puts the (+) lead on chassis ground and the (-) lead in X11 socket #3.
Attached Images
 

Last edited by bobterry99; 08-22-2017 at 11:40 AM.
bobterry99 is offline  
post #18 of 72 (permalink) Old 08-22-2017, 11:45 AM Thread Starter
Outstanding Contributor
 
H.D.'s Avatar
 
Date registered: May 2014
Vehicle: 1988 300CE
Location: Germany
Posts: 1,360
Mentioned: 36 Post(s)
Quoted: 515 Post(s)
(Thread Starter)
In order to prevent other readers from confusion I repeat what I said in post #2 about MB’s definition … actually Bosch’s definition … of the duty cycle:
Quote:
Originally Posted by H.D. View Post
... In case of the KE-Jetronic the duty cycle value refers to the square wave voltage’s ‘off’-time ...
Regarding the following statement in post #15:
Quote:
Originally Posted by bobterry99 View Post
... If a meter displays 70% its reference is wrong, and a simple remedy may be to swap the meter's leads to give a reading of 30% ...
With all my duty cycle meters (analog and digital) that is not the case. … And how could it with the given nature of square wave voltage.
If you use a voltmeter and swap the leads, the values will be the same, only once without and once with a minus sign … according to the nature of square wave voltage.

H.D.
H.D. is offline  
post #19 of 72 (permalink) Old 08-22-2017, 07:57 PM
Moderator
 
Jayare's Avatar
 
Date registered: Jun 2005
Vehicle: 86 190E 2.3L 16V, 2 95 320TE's, 02 S500
Location: Seminole, FL
Posts: 12,540
Mentioned: 10 Post(s)
Quoted: 1103 Post(s)
Lifetime Premium Member
Let's not get too far into the rabbit hole on his one guys. The information and testing steps that have been provided are appreciated.

Jayare

Sent from my XT1080 using Tapatalk
Jayare is offline  
post #20 of 72 (permalink) Old 08-22-2017, 09:57 PM
Outstanding Contributor
 
Date registered: Jan 2004
Vehicle: '03 SL500, '03 SL55, '97 SL320, (2) '91 300SL, (2) '91 500SL, '00 S500 -- all for sale
Location: Atlanta, USA
Posts: 4,063
Mentioned: 14 Post(s)
Quoted: 605 Post(s)
Quote:
Originally Posted by H.D. View Post
Regarding the following [Terry] statement in post #15: "If a meter displays 70% its reference is wrong, and a simple remedy may be to swap the meter's leads to give a reading of 30%."

With all my duty cycle meters (analog and digital) that is not the case...And how could it with the given nature of square wave voltage.
The technique of swapping meter leads absolutely works in many or most cases -- a fact known to members over in the Peachparts forum. See the 8-second video below for proof.

How is this so? I won't bother with a proper explanation, but know this: Meters like mine calculate duty cycle based upon the percent time that the meter (+) lead is at a higher voltage than the (-) lead.

.
bobterry99 is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W124 E,CE,D,TD Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome