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

[pbanders]

Here you go. I scanned it with the document reader, so there are some blank pages that you can ignore, but everything is there including the test setup and test procedure.

http://members.rennlist.org/pbanders/Ditro...on%20Manual.pdf

[nordfisch]

....
Only the MPS used for the Mercedes-Benz applications is able to compensate for atmospheric pressure differences (i.e altitude and weather). Your interpretation is correct, and I believe Volker explains it well in his response to your question.

Thank you so much for all your work and explanations, Brad.
There are some other cars / manufacturers equipped with sensor 'type III' with compensation - late Volkswagen type III, Opel (GM), Citroen, Jaguar.

Sorry, I have no time left at this time, will add explanations etc. later.

Regards
Norbert

[Dr-DJet]

Hi Brad,

good to see you here. I am still hunting for the EFI 9100 you mention in your website. However I believe that I also have some nice even Bosch internal testers that are even superior to that one. If you want, have a look at Bosch KD-JE 7400, 7401 and 7402 or the later MB version KD-JED 7500.

Best regards from Germany,
Dr-DJet

[Dr-DJet]

Hi,

when I just see the comment on pressure sensor altitude compensation. I call it the type 3 MPS. It is available for Volkswagen Type 3 and many other cars. MB used it on their 280 and 450 engine, but not on 250 or 350 engine. Many OEMs like Opel switched at one point of time from type 2 with diaphragm to type 3 with altitude compensation.

I even made a list with all available MAP sensors at list of all pressure sensors on oldtimer.tips. I also built up references for tuning them to original. Same for ECUs.

Your comments are welcome.

[JeffBowlsby]

I own an EFI Assoc 9100 for D-Jet and 8100 for L-Jet, with operating manuals. Formerly owned by the late John Larson. They are very capable testers as you know and do include a vacuum pump on the stand, separate from the tester unit.

[Dr-DJet]

I own an EFI Assoc 9100 for D-Jet and 8100 for L-Jet, with operating manuals. Formerly owned by the late John Larson. They are very capable testers as you know and do include a vacuum pump on the stand, separate from the tester unit.

Hi Jeff,

I glanced through the EFI manual and therefore know its capabilities. But the Bosch internal KD-JE 7400 is superior to it. It tests ECUs very deeply. Bosch first produced them for intenal usage only. I even believe that they were used in manufacturing ECUs for tuning them. Around 20 of them were finally installed in premium Bosch workshops throughout Europe at that time. They are extremely hard to find. I think there was none in the US.

The EFI 9100 has similiar features to the one that Bosch made for Daimler. That one was called KD-JED 7500. It does not test as deeply as the 7400.

Anyhow: If you or someone else would like to hand over his tester to a collector, please let me know

[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...>.

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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.

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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

[pbanders]

FWIW, if anyone is interested, I just put up four testers for sale in the classified forums: a Ditron 812D D-Jetronic Tester, a Janbo 112 D-Jetronic tester, a Kent-Moore 112D D-Jetronic tester, and a real rarity, a Ditron 811L L-Jetronic Tester, for you 1.8L 914 guys who need to check your cars out. Take a look if you're interested. I don't use these testers and I'd like to see them go to someone who can put them to good use.