Sacrificial D-Jet Dizzy? - PeachParts Mercedes-Benz Forum

alfaking2000 · #1 08-06-2012, 01:06 PM

Hello- long time reader, recent poster here.
I am researching an alternative to the trigger points for D-Jet cars (I own 2) and I need a sacrificial dizzy for research and development. I am primarily interested in M116-M117 units due to the exorbitant cost of the trigger points from Bosch or Mercedes Benz, but I assume there are other makes and models that may be in a similar $$$ situation. I cannot promise that the end result will be any cheaper, but the whole point is that the end result will eliminate a very expensive wear item. The conversion will be designed to be visually undetectable.
What I require is a complete dizzy with trigger points. While the trigger points don't have to be new, or even work, they cannot be modified ("adjusted"); the base cannot be distorted. Also, the dizzy cannot have wobble. I can deal with shaft end play.
I am located near downtown Los Angeles, so ideally someone may have one close by.
As an incentive for someone who has a decent unit they are reluctant to part with, I can offer the finished tested product at my cost to them, with free installation, on the unit they provide. I will not be responsible for running issues related to other defective components, bad tuning, etc.
This may take awhile, up to a year or more even, and it may come to nothing, such is the case with experimentation. Nothing will be harmed or destroyed so the unit will be returned in same condition as received (well, maybe in better condition if I have to shim the end play).
Any interested parties please pm me.

Frank Reiner · #2 08-06-2012, 03:46 PM

The greatest production volume of D-Jet parts will be VW Type 3 and 4,
1968-73, and Porsche 914/4 1970-76. The Bosch trigger set # for those models is 1 230 090 000.

The electrical function for all trigger contacts is the same. Small mechanical differences should not, I would think, make a difference to your research. A whole VW/Porsche distributor should work just as well as a MB one, and at a much lower price!

alfaking2000 · #3 08-07-2012, 02:51 AM

Thanks Frank.

Trouble is, since I do not own or have access to a 914 or a VW type 4 I have no way to real world test the finished product. I would rather not subject someone else to being the "guinea pig" for my experiment; thus the request for a Mercedes V8 D-Jet dizzy, since I have two cars already that are used every day. Since I have no spare dizzy or trigger points to experiment with, and I need both cars to run, this has to be a "plug and play" type of experiment, where if it doesn't work, I can simply swap out the entire distributor and minimize downtime.
Ultimately the loaner dizzy will be returned to its owner completely intact either with the replacement product or without. The trigger points can be worn out, dirty, burned, whatever, but the base plate must be undistorted.
If this idea works I will make units for other makes and models, Porsche included.

Graham · #4 08-07-2012, 09:00 PM

I have a spare distributor, but not prepared to give it up. But there are often old distributors for sale on eBay and on the forums (try Benzworld too) . I think I paid about $60.00 for my spare.

A couple of other points:

- At least one owner on Peachparts, bought two of the much cheaper VW trigger point sets and used them to rebuild the MB points.
- Bosch now sell a rebuild kit for the trigger points Bosch part number F 026 T03 035. As I understand it, it uses the existing baseplate and cables/socket. Pricey it seems - 400Euros or more.
- Late Jaguar D-Jets eliminated the trigger points and used what I think was a hall effect system (something like the Pertronix ignition point replacement) See below,

Only things that wear on the trigger points are the fibre rubbing blocks. You would think that someone could set a set of 4 for under $20.00.

Jaguar Info:

Quote:

Injector pulses are timed and initiated by trigger switches mounted diametrically opposite to each other within the distributor. Bosch had used a pair of miniature contact breakers (duplicated for the rare 8 cylinder / 4 injector group system mentioned earlier to provide the necessary 4 trigger pulses) in earlier applications but this was not easy to arrange within the Jaguar V12 distributor, quite apart from being seen as a retrograde step on an engine with electronically triggered ignition. By simply mounting a magnet in the "balance mass" of the rotor arm it was possible to operate magnetic reed switches encapsulated in a "trigger board" without any great difficulty although greater reliability was obtained subsequently by adopting "Hall Effect" sensors (magnetically switched transistors) instead. The early reed switch board had just three wires in a ribbon (one channel each side and ground in the centre) while the Hall Effect type had a fourth wire for connection to the switched ignition 12 volt supply.

As each trigger briefly closes a circuit to ground it initiates an injection cycle for the associated injector group starting with the primary pulse. The frequency of triggering provides a measurement of engine speed which influences the pulse circuits to provide the appropriate correction factor to the primary pulse. This function, known as the speed law, causes the injector pulse to increase gently until the speed of maximum torque is reached after which the pulse starts to shorten. This can be represented by a graph plotting pulse width against speed on which a line curves gradually upwards to a hump before finally tailing off. Component selection determines the upward and downward slopes and therefore also the peak of the curve. In this way the fuel input is matched to the volumetric efficiency of the engine although obviously without the precision (not always fully exploited) which modern programmed systems are capable of.

meltedpanda · #5 08-08-2012, 09:54 PM

I have several sets of trigger points, all been mucked with but if they help for the better good...... I 'd consider parting with them . Interesting how the old DJET guys are migrating to this post

Howdy Graham!

alfaking2000 · #6 08-10-2012, 01:00 PM

Graham:
How right you are! My XJ12C has this exact system. Once the German fleet is secured for future generations I will turn my turret gun of progress in its direction.

The Bosch repair kit for Mercedes is expensive enough that a cheaper plug and play substitution is warranted. 400 euros from partsbob is too much for what is essentially four point sets. (if I was feeling flush enough to buy them through my MBZ dealer they are over $900.00)!

As I understand it, the VW trigger point sets are NLA; please correct me if I am wrong. Otherwise that might be a good interim solution, but it doesn't solve the wear problem.

meltedpanda; If you could part with your grottiest set for the cause that would be awesome. Please contact me through pm.

nordfisch · #7 08-28-2014, 05:36 PM

Hi from Germany,

I recently developed a tool for testing and re-adjusting the trigger-points of the D-Jetronic to the original values.
This will allow to prolong the life of the contact set several times.

The tool has now been approved by VW (Porsche), GM (Opel), Volvo and Daimler-Benz V-8 - owners.

The tool I published works on all systems with just one simple modification.

I have no financial interest, the tool can be rebuilt by everyone.
The dimensions are metric - but D-Jetronic is a German system engineered under DIN-Konventions.
Maybe it's no problem for you... otherwise use a conversion-tool.

I published the tool in a German forum and would like you had a look at this: www.kad-forum.de • Thema anzeigen - Kontakteinschub "Gebiss" D-Jetronic warten und instandsetzen (scroll down for the figures).

I would like to hold all the information in one place for possibly correcting errors or making annotations just there.

It would be not so easy for me to translate all the German text - but maybe this is not necessary.
Just look at the figures... it works!

I would translate the text partially if you tell me it is necessary or would be useful.

Best regards

Norbert Fischer