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.

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[Java2570]

Thanks for posting here on the World, I saw this today on the Samba and was gonna link it but I saw Nate already asked you to post it here. Jon

[mapguy]

This is really interesting. I'm not in the market for one right now, but it would be great to see enough demand to make something like this available if/when I am.

Keep cross-posting your progress. I'd like to hear more about experience, driveability and tuning, especially if it can scale to something like a 2270 better than factory D-Jet, and what other mods would be required for that to work (injectors, etc).

I would think that a more out of the box way to upgrade our D-Jet cars to something that uses modern, easily sourced components (at a reasonable cost) would have a decent market, but I suppose we'll find out.

[shconer]

This adapter is mostly a passive device. Because the injectors are controlled on the high side the adapter has a MOSFET protected with a diode to drive the injectors as the Megasquirt is not capable of doing this and that is the only active part of the adapter. This does add some injector dead time but it has been very minimal in my testing. The final board will use surface mount components except for the capacitors, and the connector and will have some sort of conformal coating on it for added protection. So as far as experience, driveability, and tuning is concerned its really built upon the constantly evolving Megasquirt platform.

This adapter is designed for applications that want to retain the factory appearance. So its limited to stock or mild performance applications. Where the factory ECU requires replacement, or where modifications require more flexibility in the ECU. Any type of fuel injector can be used. The most limiting factors in terms of performance is the lack of ignition timing control which is a limit of the factory harness and the factory trigger system housed inside the distributor.

[JamesM]

This adapter is mostly a passive device. Because the injectors are controlled on the high side the adapter has a MOSFET protected with a diode to drive the injectors as the Megasquirt is not capable of doing this and that is the only active part of the adapter. This does add some injector dead time but it has been very minimal in my testing. The final board will use surface mount components except for the capacitors, and the connector and will have some sort of conformal coating on it for added protection. So as far as experience, driveability, and tuning is concerned its really built upon the constantly evolving Megasquirt platform.

This adapter is designed for applications that want to retain the factory appearance. So its limited to stock or mild performance applications. Where the factory ECU requires replacement, or where modifications require more flexibility in the ECU. Any type of fuel injector can be used. The most limiting factors in terms of performance is the lack of ignition timing control which is a limit of the factory harness and the factory trigger system housed inside the distributor.

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 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.

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.

-James

[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.

[shconer]

Modified mounting holes.

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1409895731.1.jpg)

[Rotary'14]

I like what you are doing!
but I do have a "simple" suggestion.
Can you add a connector on your adaptor that would permit ignition control inputs/outputs to the megasquirt. Some folks who are not too concerned with maintaining original looks might want to add edis-4 and a trigger wheel crank sensor.

-Robert

[monkeyboy]

Robert, if you are looking to do that and you don't care about looking original you should just use MS without his adapter and run new injectors and LS sensors.

This system is to keep everything stock.

I am in the final phases of my Microsquirt conversion. All LS sensors except for the TPS and Cylinder Head temp sensor. Crank trigger too.

[Rotary'14]

Robert, if you are looking to do that and you don't care about looking original you should just use MS without his adapter and run new injectors and LS sensors.

This system is to keep everything stock.

I am in the final phases of my Microsquirt conversion. All LS sensors except for the TPS and Cylinder Head temp sensor. Crank trigger too.

Hey MonkeyBoy!

I suppose you are right. I just like the idea of a plug and play set up that you don't have to make a harness for. Future expansion would just be a connector away with this set up.

-Robert

[carl07760]

i am looking to convert a 2.0 EFI to webers dual carbs. i read the forum and i would much rather use the system you are proposing.... sign me up.

[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.

[r_towle]

Can the fuel map be manipulated using this system?

This comes from a guy who have never touched mega squirt.

Looking to apply this for a stock look, yet be able to adjust the air/ fuel ratio to my liking.

[shconer]

I am still working on the design. I have since discovered how the factory late Type 3 and Type 4 TVS works. I have been working on making the board compatible with the factory TVS sensor. I might make a few non TVS compatible boards to test the basic design and my application does not require it.

The adapter does use the factory fuel injection points. If a custom harness was made a hall sensor could be used. But it might be difficult to find a connector that works. Also with no ignition control and all 4 injectors firing at the same time, the more accurate crankshaft position information might not be worth it. The factory D-Jet batch fires based on which contact is triggered. But I think simultaneous injection is the only way it can be done with the Megasquirt and the factory fuel injection points. Also having only one injector driver keeps the cost down and the engine might run a little cooler. As far as having issues with the low pulse width, only testing will tell but this has not been my experience in my application but it could be a possibility.

[ClayPerrine]

This is an intriguing project, so I did some looking at a D-Jet distributor. The Trigger points are never closed at the same time, and each side is closed for 180 degrees of the distributor rotation.

So how about this:

Program the megasquirt to treat the transition from closed to open as the Top Dead Center trigger. Use the ignition points as the "crank" trigger. You can use a standard pertronix or crane trigger to run them. Using the pertronix would requiring adding another 4 magnets. The crane is easier, just cut 4 more slots in the trigger disk.

You would have to lock the mechanical advance in the distributor to keep the timing accurate. But that just requires taking out the breaker plate and replacing the springs with some solid link.

[shconer]

This is an intriguing project, so I did some looking at a D-Jet distributor. The Trigger points are never closed at the same time, and each side is closed for 180 degrees of the distributor rotation.

So how about this:

Program the megasquirt to treat the transition from closed to open as the Top Dead Center trigger. Use the ignition points as the "crank" trigger. You can use a standard pertronix or crane trigger to run them. Using the pertronix would requiring adding another 4 magnets. The crane is easier, just cut 4 more slots in the trigger disk.

You would have to lock the mechanical advance in the distributor to keep the timing accurate. But that just requires taking out the breaker plate and replacing the springs with some solid link.

Funny you should say that. I had a similar idea that I am also working on. Replacing the points with a cam and crank trigger wheel inside the distributor and a PCB with dual hall sensors. I have designed a PCB to replace the points and 3D printed a few trigger wheels to prove the idea. But this would be better suited to a more complex system with individual coil packs and sequential injection. An install not interested in keeping an original appearance but a clean install.

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1414030951.1.jpg)

[mr2by4]

Funny you should say that. I had a similar idea that I am also working on. Replacing the points with a cam and crank trigger wheel inside the distributor and a PCB with dual hall sensors. I have designed a PCB to replace the points and 3D printed a few trigger wheels to prove the idea. But this would be better suited to a more complex system with individual coil packs and sequential injection. An install not interested in keeping an original appearance but a clean install.

(IMG:http://www.914world.com/bbs2/uploads_offsite/clubveedub.ca-17863-1414030951.1.jpg)

Now that is something I need!

[revhi109]

I like everything I am seeing here. I really want modern electronics and be able to use the stock wiring harness. Ive been wanting to get megasquirt for my 914 but didnt want to take on another project. The more plug and play the better.

[Bebosko]

Robert, if you are looking to do that and you don't care about looking original you should just use MS without his adapter and run new injectors and LS sensors.

This system is to keep everything stock.

I am in the final phases of my Microsquirt conversion. All LS sensors except for the TPS and Cylinder Head temp sensor. Crank trigger too.

Hi MonkeyBoy,

I'm also in the process of converting my 914 to run on an ECM.
If you are still looking for a TPS setup, I made a few adapter plate for a bosch sensor.
You can search on ebay for: Porsche 914/VW Throttle TPS Adapter/Bracket MegaSquirt ECM

I'm also in the process of making an IAC controller that will accept a PWM signal to control the position.

Regards,

Julien

[monkeyboy]

I have mine running already, but the adapter for the TPS looks a lot like that one.