Help with Ignition Coil output and LED (D14)operation please

[Subaru_EA82_4EAT_AWD]

I am up to the 'setting up' stage with my MS3 + MS3X install.

I have tested the Injector output and it seems to be working.
I am having a little trouble with the Ignition output and I was wondering if I could have some help please:

I am following this guide the best I can : https://www.diyautotune.com/support/tec ... -rx-turbo/
The EA82 turbo engine uses a single coil with a distributor for spark.

Unfortunately the guide doesnt go into detail about the board build details. When I built my board I set it up for a single coil high current output on D14 as I assumed that's would what be required to run the ignition.
I have the output set as going high and spark set to LEDs spark (Is that right, for just one output, there isnt an option for just one LED?)
Today when I ran the spark test in tunerstudio I got no spark.
I am beginning to wonder if I should be using a logic level output as the stock ECU outputs spark to a 'power transistor', not directly to the coil.

Here is a picture of the coil with the 'power transisitor" attached, is that a 1980's way of saying 'Ignitor'?





And the FSM schematic:



Thanks in advance for the help.

[grom_e30]

why not just wire the megasquirt spark output directly to the coil terminal bypassing the stock ignition transistor

[DaveEFI]

why not just wire the megasquirt spark output directly to the coil terminal bypassing the stock ignition transistor

I'd prefer to use a buffer for this. To provide some protection to the processor in event of a fault or finger trouble.

[grom_e30]

i was referring to the bip373 thats connected to d14, wiring that directly to the coil post bypassing the factory ignition transistor.

[Subaru_EA82_4EAT_AWD]

I had thought of that, but would prefer to connect it in the original configuration at this point, as I still need to be able to revert back to factory ECU for my weekday duties until I get my MS3 fully operational.

[grom_e30]

sounds like you have some soldering to do inside your ms3 then to set it up for logic level ignition output.

[Subaru_EA82_4EAT_AWD]

So, you think the 'power transistor' acts as an ignitor, and a logic level signal would fire the coil?

Perhaps I should try one of the MS3X outputs and see what happens? I just dont want to damage the ms3x and want to be sure its safe to try...

[grom_e30]

yeah id say its an ignitor

[DaveEFI]

i was referring to the bip373 thats connected to d14, wiring that directly to the coil post bypassing the factory ignition transistor.

Ah - sorry.

[DaveEFI]

yeah id say its an ignitor

I hate than name. It's only a small part of an igniter circuit.

[dontz125]

I'm going to say that 'power transistor' is a PNP device - it's connected to +12v, not GND. In that case - and I assume you have a BIP373 or equivalent fitted since you mentioned building for high-current drive - wire the WY wire to pin 36 on the DB37, and operate the MS exactly as though you were driving the coil directly. R330 from D14 to IGBT_In, 'Going High', etc.

[billr]

I think it is indeterminate as to whether that driver is PNP or NPN. The schematic lumps the coil and driver in one functional box, without showing all the connections to it. That 12V feed could be going to the coil + in the conventional manner. Also, the coil "load" could be in either the collector or emitter path; we simply don't have enough info to know. (Note: I am referring to it as if it was a BJT, but it could be FET; same basic comments apply to FET)

[Subaru_EA82_4EAT_AWD]

I'll upload a system schematic tonight, that may help.

[Subaru_EA82_4EAT_AWD]

...


There are also 2 wires that link the Power Transistor to the Coil which arent shown in the diagram, (as the 2 units are apparently treated and replaced as an assy) they come off the other side of the power transistor and one is connected to each of the coil terminals.

Here is the flow chart for testing the coil which also may help:

[Matt Cramer]

The board in that build guide used JS10 as a 5 volt logic level spark output. I would use an MS3X spark output when using an MS3X on this engine, and set its output to Going High.

[dontz125]

Yeah - that's a low-side driver, grounding (it appears) through the bracket and chassis.

[Subaru_EA82_4EAT_AWD]

Thanks, that's great! I'll give it a go.

It is okay to leave the high current circuit on D14 and just have it dormant or will it affect the LED operation?

[dontz125]

Just leave the BIP etc in place; you now have a fairly robust low-side driver for use as an output.

[Subaru_EA82_4EAT_AWD]

I know this is most likely a stupid question but the LEDs get left in the board when you are adding outputs 'to' them right?
I assume the they then illuminate when the output is active instead of their original purpose?

[dontz125]

LEDs can be left or clipped; it's the transistors doing the work. And yes, they come on according to the output function, not 'Squirt', 'Warm', etc.