Ditron 812D D-Jetronic Tester, Searching for instruction Options

[nordfisch]

Hi,
this forum was recommended to me... and this is really a great place for guys like me, interested in the D-Jetronic system.
We have a forum in Germany, German and English language "oldtimer.tips", too.
We are more conservative than you are, mostly just trying to find out everything about the system and how to repair the components. We are hobbyists mostly MB, but also BMW, VW, Opel, Porsche, Renault, Citroen, Lancia... all the car brands D-Jetronic was installed in.
I by myself designed a tool for re-adjusting the trigger points to the original values. Simple to be rebuilded if you have a lathe - I will send you a figure on request.

Now my own request:

Does anyone here own a Ditron 812D tester, too?





I own such a device, but without any instruction.
It once came to Europe with the instruction, but it got lost.
I bought the Ditron some months ago on ebay from switzerland - the seller told me he had bought it many years ago at ebay USA.

It's no problem for me to understand and use the basic testing functions, but this tester is not only a testing - but an ECU-simulating device.

I don't really need the Ditron 812D to diagnose or optimize my car - I own some other testers.
But because the D-Jetronic-system is my hobby, I would like to understand the additional function, i.e. what the manufacturer intended the user to test / adjust with it.

Hope that someone still has the instruction for the tester...
My tester has serial #119 - don't know how many were built at all.

P.B. "Brad" Anders described the tester: D-Jetronic Testers as being similar to the Janbo Model 112 he described more detailed.

Does anyone own the tester / the instruction?

Please help...

Regards
Norbert

[Bleyseng]

Interesting site but no MPS adjusting info other than "don't touch".

[nordfisch]

Interesting site but no MPS adjusting info other than "don't touch".

It's not my site...

But you find any information there. Look at section 4.3.

You can't really tune a MPS. Just mistune it. The MPS is the very central device the ECU does get information from how much fuel to inject at the different load-conditions.

It has roughly the same meaning as the 'space cam' ('Raumnocken') in previous mechanical injection systems.

The D-Jetronic is a fully integrated system - depending on any single part operating within the motor-specific limits that are pre-defined by the factory-compiled individual setup.

Regards
Norbert

---------- What about the Ditron manual? -------- (IMG:style_emoticons/default/pray.gif)

[pbanders]

Interesting site but no MPS adjusting info other than "don't touch".

It's not my site...

But you find any information there. Look at section 4.3.

You can't really tune a MPS. Just mistune it. The MPS is the very central device the ECU does get information from how much fuel to inject at the different load-conditions.

It has roughly the same meaning as the 'space cam' ('Raumnocken') in previous mechanical injection systems.

The D-Jetronic is a fully integrated system - depending on any single part operating within the motor-specific limits that are pre-defined by the factory-compiled individual setup.

Regards
Norbert

---------- What about the Ditron manual? -------- (IMG:style_emoticons/default/pray.gif)

Actually, as Jeff and many of us know, the MPS can be "tuned", meaning that it can be adjusted to factory specifications, or the specifications can be precisely set for specific running conditions. Details of the process are on my site, and Jeff and others have used these procedures for years as part of rebuilding MPS's and adjusting MPS's that have been "fiddled with" by others. There are a number of rebuilders who have been doing this for years, such as the old Bret Instruments outfit (since bought). The guy who ran it had a long phone conversation with me some years ago where he described the bench setup that he used to take "golden units", aka NOS MPS's, and come up with parameter sets that could be used to calibrate rebuilt units to the same characteristics.

Note that while there are many MPS's, with a number of feature design differences, such as varying types of damping devices, presence or non-presence of full-load diaphragms, etc., our experimentation here in the 914 world has been restricted to the MPS design used for our application: the dual-aneroid cell, full-load diaphragm model. For this model, there are three adjustments that can be made: part-load mixture (central adjusting screw), full-load mixture (full load stop), and part-to-full load transition range (outer adjusting screw). Procedures are given on my page on how to make adjustments and what the expected effect on mixture will be.

For "tuning" applications, the MPS can be adjusted while the car is on a chassis dynomometer and connected to an AFM meter. This can assure ideal operation of the system across all running ranges.

In cases where the volumetric efficiency (VE) of the engine has been significantly altered (e.g. different camshaft, valve sizes, displacement, boring of the throttle body, etc.), adjustments to the MPS will not be sufficient to compensate for the changes in the VE curve, as the MPS is blind to the VE curve effects on mixture. In these cases, the most practical solution is to fit a modern speed-pressure EFI system to the car and remove the D-Jetronic system, as modern systems incorporate VE mapping (e.g. Megasquirt and others). If you really, really, want to retain the D-Jetronic system, and the changes to the VE curve are not too radical, then it is possible to modify the waveform generator circuits on the daughter card in the ECU to accommodate the altered VE curve. I believe this was the initial motivation of Frank Kerfoot, who developed the ECU circuit diagrams we used to reverse engineer the ECU. He was doing SCCA racing and wanted to get an advantage over his competitors, yet stay legal in his classification. Not sure it it worked or if he ever actually did it!

[nordfisch]

...
Actually, as Jeff and many of us know, the MPS can be "tuned", meaning that it can be adjusted to factory specifications, or the specifications can be precisely set for specific running conditions. Details of the process are on my site, and Jeff and others have used these procedures for years as part of rebuilding MPS's and adjusting MPS's that have been "fiddled with" by others. There are a number of rebuilders who have been doing this for years, such as the old Bret Instruments outfit (since bought). The guy who ran it had a long phone conversation with me some years ago where he described the bench setup that he used to take "golden units", aka NOS MPS's, and come up with parameter sets that could be used to calibrate rebuilt units to the same characteristics.

Note that while there are many MPS's, with a number of feature design differences, such as varying types of damping devices, presence or non-presence of full-load diaphragms, etc., our experimentation here in the 914 world has been restricted to the MPS design used for our application: the dual-aneroid cell, full-load diaphragm model. For this model, there are three adjustments that can be made: part-load mixture (central adjusting screw), full-load mixture (full load stop), and part-to-full load transition range (outer adjusting screw). Procedures are given on my page on how to make adjustments and what the expected effect on mixture will be.

For "tuning" applications, the MPS can be adjusted while the car is on a chassis dynomometer and connected to an AFM meter. This can assure ideal operation of the system across all running ranges.

In cases where the volumetric efficiency (VE) of the engine has been significantly altered (e.g. different camshaft, valve sizes, displacement, boring of the throttle body, etc.), adjustments to the MPS will not be sufficient to compensate for the changes in the VE curve, as the MPS is blind to the VE curve effects on mixture. In these cases, the most practical solution is to fit a modern speed-pressure EFI system to the car and remove the D-Jetronic system, as modern systems incorporate VE mapping (e.g. Megasquirt and others). If you really, really, want to retain the D-Jetronic system, and the changes to the VE curve are not too radical, then it is possible to modify the waveform generator circuits on the daughter card in the ECU to accommodate the altered VE curve. I believe this was the initial motivation of Frank Kerfoot, who developed the ECU circuit diagrams we used to reverse engineer the ECU. He was doing SCCA racing and wanted to get an advantage over his competitors, yet stay legal in his classification. Not sure it it worked or if he ever actually did it!

Hi Brad,
thank you so much for doing the scan-job...
I did a clean-up at the document and deleted the empty pages. I then realized the last page doesn't belong to this manual - maybe it belongs to the Ditron 811L (L-Jetronic-tester).

I already had most of the information before - from your page and the informations I got about the Kent-Moore-Tester.

But the 'paper' I now got from you gives me much more information about the tester - regarding the intention of 'Ditron' to tune and repair the MPS using this unit.

I knew before the Ditron isn't able to diagnose my car in full - because my car has the full-load-switch integrated in the TPS. The Ditron doesn't support testing this.

But the VW 1218 can do this - because the late VW Type III has such a switch, too.
But this Tester isn't able to test the injectors for continuity - i.e. not that ones that are paired in 6-cyl. applications.
Nor can it test my ECU - my car doesn't have an over-run-shutoff function.

(I don't really need this testers, but it is my interest to find out the specific differences between the differen D-Jet-applications...)

Nor do I want to 'tune' the components of my car. I own some ECUs and MPS with the same Bosch-part-# - but my car runs best with the 'original' components.

We found out Bosch didn't report 'mininimal changes' done to the parts to all of the car manufacturers and/or these didn't inform the workshops.
Nor are these changes to be found in any document...
At BMW, for example, parts are marked with red / blue points, Opel parts aren't marked.
Installing a fully operating and fully-tested MPS with the same Bosch# can result in an engine with highly reduced performance.
Therefor the encoded production date on the units is quite important for us Opel-guys <most of them don't know...>.

--------

Volker Huck does the MPS-repair the same way you reported, using the values taken from 'golden units' - as many of them as he can get.

--------

Concerning the tuning the D-Jet-Equipment of modified engines we have an additional idea, too.
Three decades or so ago a company in Germany developed an additional box, meant for adding an catalytic converter to the D-Jet-system, using an O2-sensor.
This high-priced unit 'ST28' produced by G+M, Gladbeck is available up to this time and could solve all the problems.
You can see a figure here (identically suitable to other D-Jet-cars): https://oldtimer.tips/en/forum2/jetronic/15...g?start=20#1359

Best regards and (IMG:style_emoticons/default/pray.gif) again

Norbert