[Hugues]

I have a Pinzgauer 710M, air cooled 4 cylinders petrol engine, dual carbs, Bosch distributor with points and centrifugal weights for advance, coil, plugs, no vacuum advance. No ECU, no electronics.

I'm struggling to get my advance curve right playing only with the springs, i'd like to have more control and add more modern options like MAP and temperature sensors, exhaust O2,..
No fuel injection for now, keeping that for later maybe.

As i'll travel with the truck into very remote places, i need to keep a way to revert quickly (couple of hours, simple tools) to the mechanical-only advance system in case the electronic components fail.

In the wiki pages and in the forum, i have not found a wiring diagram that would use my current setup (points, dizzy, coil, plugs). I don't necessarily insist on using my points, but would like to leave everything in place so i can revert to stock configuration quickly. I can eventually replace my points with a Hall sensor if this helps. And lock my dizzy weights of course, in a way i can undo this.
The last wiring diagram in the wiki page showing a distributor, also shows a single channel ignition module (Such as the common Bosch 124), I don't have such system. Very old school.

What would be a simple system and wiring diagram for such setup ? I can add a wheel and sensor on pulley if absolutely needed.

[dazq]

Simplest option would be leave all the old stuff alone and in place , just disconnected.
Then use a new trigger wheel for speeduino which used the original coil and HT system.
Easy to revert back (1 wire) to the points if needed.

[PSIG]

As i'll travel with the truck into very remote places, i need to keep a way to revert quickly (couple of hours, simple tools) to the mechanical-only advance system in case the electronic components fail.

Welcome! That's cool, as I did a very similar EFI+ignition conversion to a Pinz a long time ago. It was a conversion for mission-critical deep safari, where the truck would be away from support for weeks or months at a time. The conversion used the original points for input trigger (carry a spare set), an ignitor, and stock everything else. It was successful, as years later I was told it was still working the bush, and was retro'ed to carb and points-fire about once a year to verify that stuff was still working — but never needed to.

For ignition conversion, you could use @dazq's suggestion and disconnect the distributor wire for points. Or for a first-shot, use the points to trigger as I did going on 20 years ago with an MS v1. High points: I used a Bosch 034 (DSM-Ford-Mazda-Subaru J121) ignition module to fire the coil. I locked the mechanical advance (under the points plate) with a wire wrap, but if you're slick a single hole with a machine screw could be accessed through a plate hole so plate removal could be avoided in the field.

The distributor points wire was removed from the coil and moved to the ECM trigger input (VR+). The PCB would be set to Hall, and use the input pullup ON. You have signal. Set the engine parameters and Basic Distributor decoder, ignition dwell, etc, and ignition output signal voltage at 5V. Then connect IGN1 output to the Bosch or other module, and the module to the coil and ground (like the Wiki), but the module does not need V+.

After setting a reasonable Spark Table (stock at first) and cranking values, check commanded timing against actual with a timing light, and adjust with Trigger Angle. Or just fire that puppy up, check timing, and give it a nice tune. 8-)

Bosch 034 - DSM J121 Ignition Coil Driver.jpg (38.84 KiB) Viewed 838 times

[Hugues]

Thanks guys for your input, much appreciated.
I carefully "dissected" your input with the help of ChatGPT and also the wiring diagram from the Wiki for Distributor setup (first picture below).
I now have a better understanding of that part of the system. I really want to understand and not only remember which wire goes where, that will be critical for my application.

Now, i will test the system first using my current points as an input ( i can check for Hall sensor conversion later on). So I have modified the wiki diagram, second picture, as per following:
- used 3 pins Bosch 034 instead of 4 pins 124
- removed the red power wire into the Bosch 034 (i understand it's "powered" from the Speeeduino signal wire)
- connected my points wire out of my distributor to the Speeduino inputs (orange wire)

Is this correct ?

And if you allow me a few more questions then:
-would be nice to add a knock sensor at some point, as i'll be travelling to countries with low octane fuel. Somone in the Pinz forum was saying it could be difficult to find a suitable knock sensor for such an engine, not sure why though, your views ?
-I live in Switzerland, i'm looking for an already assembled board, i see some many variations, any pointers to share for my application, knowing i might also look into fuel injection later on but not a must, and certainly not enroll my Pinz into drag racing LOL

thanks !

Original wiring diagram from Wiki page:

wiring diagram.png (169.75 KiB) Viewed 763 times

Revised wiring diagram:

wiring diagram new.png (174.5 KiB) Viewed 763 times

[PSIG]

Looking good. Keep in-mind, your setup already includes a power circuit for the coil, so the relay that would normally be used in a "fresh" system is not necessary.

Effectively, you can have only the points wire re-routed to the ECM, and the control of the coil switched to the ICM/ECM. Simplify it in your head that way, and a copy of your wiring diagram with the simple drawn re-routing may give you that perspective you want so you know how it will go, and how it will swap back if necessary.

Even the ECM power, MAP line, added CLT, etc, could remain connected, just swapping a couple IO connections. From that perspective, matching connectors to what is there now, or insertion of a convenient set, will allow a simple unplug > replug to do the swap-back.

Sort-of:

Swappable.jpg (103.34 KiB) Viewed 725 times

[Hugues]

Thanks for the input.
After scratching a bit the interwebs, do I get it right that
I cannot feed my 24V signal coming from my points directly to the Speeduino inputs ?
I need to convert this down to 5V and clean it with an opto-coupler ?
That sounds reasonable.
I've updated my diagram below.
I would happily buy a toothed wheel for my crankshaft pulley but the Pinz has a conical one with the bolt recessed..a bit of a pain for me for now.

[PSIG]

After scratching a bit the interwebs, do I get it right that
I cannot feed my 24V signal coming from my points directly to the Speeduino inputs ?

This continues to get easier. Your points to not send voltage. Your coil(-) -or- the ECM send voltage for the points to switch to ground.

From a different conceptual direction - if you disconnect your distributor from the coil, the distributor wire is dead. Connect the ECM signal wire to the distributor wire, and the ECM will send 5V to the points to be grounded intermittently, 5V-GND-5V-GND… Reminder; there is no (+) wire to a points distributor to source voltage. It is a passive mechanical switch from the voltage source (coil or ECM) to ground.

I would happily buy a toothed wheel for my crankshaft pulley but the Pinz has a conical one with the bolt recessed..a bit of a pain for me for now.

See where this initial conversion goes. Discover true strengths and weaknesses. Modify the system to solve more weaknesses and get more strengths. There are multi-tooth solutions (if needed) the vast majority of the time, and often do not include a crank wheel, or a crank wheel not as typically envisioned.

[Hugues]

Thanks for guiding me,
I've been busy these past few days to find a way to attach a toothed wheel to my pulley
I've found a way using an adapter, not too crazy expensive, can have the parts machined online,
this way i can run stock with my current mechanical advance (no need to lock it), and use Speeduino for data acquisition only and see if my crank trigger signal is steady.
Then I should be able to compare the output from Speeduino with the recommended stock Pinz advance and match it,
then i can switch to Speeduino to control my advance, starting with idle check, just a simple "static" map that will keep my advance as-is,
then when i'm confident with what i see and hear, i can slowly integrate other sensors one by one, MAP first, and impact my advance.

[PSIG]

Sounds like a plan. Be aware the advance curves will different (sometimes very different) than stock, and to keep an eye on rotor phasing. Not a worry now, just keep it in the back of your head to check as your make progress.

[Hugues]

Just an idea i want to check here,
My Pinzgauer petrol engine has 2 carburetors,
at the base of each carburetors are 2 solenoid valves, 24V
(aka idle stop solenoids, anti-diesel solenoids, or fuel cut-off solenoids,)
On the Pinz, they only serve to cut off fuel supply when you switch the ignition off, to prevent the engine from running if auto-igniting due to hot temperature.

Could I drive these valves with the ECU outputs ? One possible usage could be:
-when i'm going down hill and simply using engine breaking (I live in Switzerland, lots of hills), today my carbs probably still spend some fuel despite i'm not pressing the accelerator. Maybe not much, but still.
-I could imagine programming the ECU to shut the solenoid valves off under certain conditions : throttle position closed, a minimum RPM to reach, MAP sensor input,.. when i'm using engine breaking.
I think it's called Deceleration Fuel Cut-Off (DFCO) on modern engine,

Could this work ? Any other possible usage you can think of ? Not that I pretend replacing fuel injectors with these of course. They are more like fuel restrictors actually. We could imagine cycle them on and off with a pulse-width modulation , probably not crazy fast but could be used to transition in and out of DFCO.