Ditron 812D D-Jetronic Tester, Searching for instruction |
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Ditron 812D D-Jetronic Tester, Searching for instruction |
nordfisch |
Dec 11 2015, 07:25 PM
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#1
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Member Group: Members Posts: 86 Joined: 11-December 15 From: Germany Member No.: 19,451 Region Association: None |
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 |
Jan 24 2016, 04:13 AM
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#2
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Interesting site but no MPS adjusting info other than "don't touch".
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nordfisch |
Jan 24 2016, 07:53 AM
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#3
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Member Group: Members Posts: 86 Joined: 11-December 15 From: Germany Member No.: 19,451 Region Association: None |
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 |
Oct 23 2016, 07:29 PM
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#4
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Senior Member Group: Members Posts: 939 Joined: 11-June 03 From: Phoenix, AZ Member No.: 805 |
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! |
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