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

[JeffBowlsby]

Norbert, I have spent a little time on that oldtimer website and while I virtually all that I see, I have one little nagging issue.

He refers to the MPS as a MAP sensor and it is not. Modern cars use a MAP sensor but the MPS is not a MAP sensor. Its been a long time since I read it and I do not own a copy any more, but I think it was the big blue Bosch book on fuel injection that describes the differences. Forgive me if I misstate the differences but this is what I recall:

Manifold Pressure Sensor = senses intake manifold pressure which is a value in relation to atmospheric pressure.

Manifold Absolute Pressure = would be an absolute pressure value value not related to atmospheric pressure.

Can you speak to V. HUck about that for clarification?

[Dr-DJet]

Norbert, I have spent a little time on that oldtimer website and while I virtually all that I see, I have one little nagging issue.

He refers to the MPS as a MAP sensor and it is not. Modern cars use a MAP sensor but the MPS is not a MAP sensor. Its been a long time since I read it and I do not own a copy any more, but I think it was the big blue Bosch book on fuel injection that describes the differences. Forgive me if I misstate the differences but this is what I recall:

Manifold Pressure Sensor = senses intake manifold pressure which is a value in relation to atmospheric pressure.

Manifold Absolute Pressure = would be an absolute pressure value value not related to atmospheric pressure.

Can you speak to speak to Volker about that for clarification?

Hi Jeff,

that is an interesting question and I only see it now when I surf through links to my website. Let me introduce myself: I am an D-Jetronic enthusiast naming myself Dr-DJet and I run the forementioned webstite oldtimer.tips with the D-Jetronic compendium and a forum dedicated to D-Jetronic of all manufacturers.

It is a pity that this question never made it to me. I admit that I was not aware of the English acronym differences MAP and MPS. But you will see that I am not so wrong either and not 100% correct too.

As you already noticed there were three types of vacuum pressure sensors. Type 1 (as seen in early VW type 3 and Citroen) has 2 evacuated aneroid cells and it measures absolute pressure, nothing else. So it is a MAP sensor.

Type 2 also has 2 absolute pressure aneroid cells and like type 1 it measures absolute manifold pressure. But then we have the full-load diaphragm which opposes some environmental pressure on the armature shaft. It is only a smaller side effect. Type 2 is not meant to measure differential vacuum to environmental pressure, but it still has a slight influence. For that reason I have to adjust environmental pressure and absolute vacuum when I adjust one of them. I would still call type 2 a MAP sensor. This is the type you all ride in 914s. After 40 years diaphragms tear in this type and I just made a nice video how you check that.

Type 3 (latest version in many cars like my MB 450 SL) has a differential pressure cell AND an absolute pressure cell. So it is a MAP sensor and a differential vacuum pressure sensor (MDPS if you like) at the same time. Here I have to measure absolute vacuum and 2 environmental pressures to verify/adjust a type 3 pressure sensor.

So the question is whether you want to nag about me calling type 3 sensors a MAP sensor. There I am only correct for one of the 2 cells. In type 1 and type 2 I am correct. If there is no further errors, I can live without it.

In total I prefer to call all 3 D-Jetronic vacuum pressure sensors MAP sensors. I hope you do not mind. I would also welcome you to my forum to discuss such interesting questions in more detail if you like.

Best regards,
Dr- DJet (Volker)