rusefi.com

Stock engine. Mazda B3.

Right now I've only started ordering things, so no pics or progress yet. I'll be using the Frankenstein board and a round bulkhead connector to do a completely DIY harness. I have some ideas for a case too, but that's later.

For now I'm digging into the docs and ordering. So that's where I am.

Mazda_B_engine is starting to dominate here

Glad to you have on board!

Just found I have a reluctor wheel distributor. Will this work?

Reluctor as in "Variable Reluctor" (VR)?

You would need the MAX9926 chip from the BOM.

Yep. Looks like this inside.


Strange. There are 3 different types of dists that came in the Festiva.

So I'm looking at the schematics now. If I'm understanding this correctly the 6 channel high-side driver would be able to do the 4 injectors and fuel pump and ignition. Any reason not to go that way instead of using 6 mosfets like shown in the 12 channel injector driver schematic? I don't understand which way to do it. They seem to be 2 different ways to do the same thing.

Let me welcome you into the "Electronically challenged of the world, unite!" club. You do not have to adjust your signature, but you can if you want to.

Fuel injectors are controlled by connecting and disconnecting their GND wire - the +12V is constantly routed to the battery. So, you would need a low-side driver for the injectors. Also something about current and heat dissipation, whatever these terms mean. The mosfet drives the injectors directly.

Fuel pump relay - also low side. That's just a relay, not the actual pump - so, the current is lower.

Ignition module is often controlled by +5v - do not ask me why. That's where you usually use a hi-side driver, that's a simpler design as on the Frankenstein pictures.

Before Frankenstein and the hi-side driver, we had a dirty hack on the low-side board: with two extra resistors one of the low channels was turned into a high-side channel. That's what I was using before F. So, you have options for ignition module. That's the only output channel where you have options. With current F 0.1 it would be easier to solder the low-side hack - the chip is larger then the hi-side chip.

Thanks for the welcome. I understand only the basics. Enough to get in trouble.

So I need the low side design for everything but the ignition which I can use a modded low side mosfet channel to do. Gotcha.

Found the hack on the sch.

I don't see a wattage listed for the 5k resistors for the VR chip inputs. No listing in the BOM at all, but the diagram shows them.

There was no 5k on the BOM because for some weird reason 5k resisters are unreasonably expensive on digikey.

I've just updated the BOM with a 4.99K which would work just fine.

sketchman wrote: Strange. There are 3 different types of dists that came in the Festiva.

88-89 carb had one type, 89 auto was its own thing (different wiring harness, ecu, distributor...) 90+ were the same. What year are you working with? If its a 90+ it should have an optical sensor, same as on my B6.

I opened the dist. It's a VR type. For sure. Looks just like the pic I linked.

Thanks rus for the update.

On the SD card sch page it shows some diodes called D351-D353. No listing in the BOM for them. Are they needed?

Also didn't see an SD slot part # 101-00708-64-ND for Digikey.

sketchman wrote:On the SD card sch page it shows some diodes called D351-D353. No listing in the BOM for them. Are they needed?

Great question!

These are 5v power supply, 3.3 power supply and 'usb connected' LEDs - these are useful on the individual modules, the pieces Frankenstein was made of. I would guess there are more examples of 'power supply' LED (and it's resistor) being removed while making the Frankenstein.

Sweet thanks. About to place my order now.

Also there is a mention of a "stripped down" version of the STM board for use with this project. Is there a special part number for that?

Not sure what it is. Probably some hint of http://rusefi.com/forum/viewtopic.php?f=4&t=381 ? That's still WIP

For now you would need stm32f4discovery - this name is also the part number.

Ahh. OK.

Looks like somewhere around $150 for a complete ECU using the Frankenstein board. Pretty impressive.