BOSCH D-Jetronic Megasquirt Adapter Options

[shconer]

I have built a prototype board that adapts the factory Bosch D-Jetronic card edge connector in my 1969 Squareback to the DB-37 connector of my Megasquirt 2. Also I retrofitted the factory pressure sensor with a modern sensor inside. With some small modifications to the Megasquirt board to accommodate the external MAP sensor. I have created a plug and play system that works with the factory harness and does not require any further modifications or additions. Alternately you could instead connect the standard Megasquirt onboard MAP sensor with a hose to the manifold and lose the factory appearance. I have done some testing with the prototype board and I am in the final stages of developing the final version. I have designed it to be compatible with early and late type 3 cars as well as all fuel injected 914's. Before I ordered PCBs and components I thought I would see if there is any interest out there for something like this. The final PCB is designed to mount inside of the factory case with room for the Megasquirt. An assembled adapter would cost approximately $80 CAD. This could be a cheaper solution for someone with a malfunctioning D-Jet ECU or a dual carb conversion. The factory idle control system still controls idle. This is a fuel only set up and the factory distributor and ignition is used. Also there is no provision for EGO feedback, it is a open loop system. This adapter works with MS1 or MS2 V3.0/3.52.

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864953.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864953.2.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864954.3.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864954.4.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864955.5.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409864955.6.jpg)

[shconer]

Very cool. I have done the same thing on a couple of my cars but made the injector circuit change on the MS board itself (switched power through the injector drivers rather then ground)

I am not sure I understand what you mean. My design switches on the high side of the injector through an unmodified factory harness. It does not switch through the ground.

I actually have a partially mocked up board based on the MS 2.2 design that will just solder directly to the d-jet edge connector. Life has been to busy for me to finish and send out for fab though.

Duplicating Megasquirt boards in whole or part would violate Megasquirts patents and copyrights so I have designed an original adapter board as a Megasquirt accessory. I first tried to assemble a Megasquirt in a way that would allow high side switching but found it nearly impossible to do so and retain the flyback functionality. Also I think having a standard MS1/2 makes it easier to support.

How does the connection hold up with the traces just printed on the PCB like that? Considered that route as well but the connector is a bit fatter then a normal PCB, wasnt sure it would work.

The board edge connector is the factory set up for the early Type 3. So in an effort to make it compatible with everything I went this route. In the testing I have done in my Squareback I have had no problems. I have connected and disconnected it many times during development and it is more durable than I thought it would be. Your commenting on the connector made me notice that the 914 ECU PCB has different mounting hole locations than the early T3 PCB. I will modify the adapter design to fit both.

[JamesM]

I am not sure I understand what you mean. My design switches on the high side of the injector through an unmodified factory harness. It does not switch through the ground.

On the injector circuit change, I just mean that I made that modification on the MS board itself rather then add an external injector driver on an adapter board (which is what i am assuming you are doing)

Duplicating Megasquirt boards in whole or part would violate Megasquirts patents and copyrights so I have designed an original adapter board as a Megasquirt accessory. I first tried to assemble a Megasquirt in a way that would allow high side switching but found it nearly impossible to do so and retain the flyback functionality. Also I think having a standard MS1/2 makes it easier to support.

Indeed it would, which is one of the reasons it would most likely never be sold (no time to support would be the other), this is more of a personal project for me. The board I am currently running is also an unofficial board (MiniMS) based on the 2.2 design. I own an official 2.2 board as well that i used to run, and i paid nothing for the MiniMS board, so morally i don't feel bad about anything here. I have never liked running with the flyback circuit, especially on the 2.2 boards so I completely removed it and just run it using the stock resistors found in the D-Jet ECU case, though i may ditch those as well and just switch to high impedance injectors as i have heard of some that may be a plug and play swap as well as being more appropriately sized (2.0 type 4 injectors are HUGE for the application 36lb/hr)

The board edge connector is the factory set up for the early Type 3. So in an effort to make it compatible with everything I went this route. In the testing I have done in my Squareback I have had no problems. I have connected and disconnected it many times during development and it is more durable than I thought it would be. Your commenting on the connector made me notice that the 914 ECU PCB has different mounting hole locations than the early T3 PCB. I will modify the adapter design to fit both.

Thats pretty cool! I have a few non type 4 d-Jet ECUs but never seen one with the connector just being traces on the board. Had i known Bosch did that at one point I might have tried it myself. If it works it works!

A few more questions, because i really like this stuff.

Where are you picking up your tach signal from? Stock injector points?

Have you seen Marios (thedubshop.net) crank triggers? I have been thinking it would be cool to wire one thought the stock trigger point connector.

From your drawing it appears as though you are firing all 4 injectors as a single bank. Why the decision to go this route? Is that the way type 3s normally fire? Doing this using 2.0 injectors and you can see issues due to the insanely small pulse width required.