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Rednaxs60 wrote:
Thu Nov 24, 2022 12:40 am
Changed from GOING LOW to GOING HIGH. Did this because the testing I did with the OEM ECU had 12 VDC on three legs of the igniter wiring to ground. GOING LOW in TS had 12 VDC on none leg only.
Something amiss with 3 legs having 12V. The test is to see if the driver grounds the coil when signal voltage (5V or 12V selectable) is applied, or when not applied. If the coil is grounded to pass current (dwell) when signal voltage is applied, it is a Going Low setup. If the coil is grounded when signal voltage is NOT applied, it is a Going High setup. The setting is what the signal does when the coil fires—going low or going high to fire the coil (not dwell it).

The animated image in the Hardware > Outputs > Coils section of the old Wiki is an example of Going Low, where the signal goes low (to zero volts or ground) to induce the coil to fire.
Rednaxs60 wrote:
Thu Nov 24, 2022 12:40 am
Hydro locked the engine while doing this. First time I had had this happen. Thought about it and there is a function/setting in the Speeduino manual under cranking settings called "Priming Pulsewidth" … There is no specific TS setting to match …
Yes, the Priming Pulsewidth is what pulses the injectors before cranking. Turn that setting to all zeroes to prevent repeated priming flood. While it can clear bubbles, injector priming typically adds startup fuel and is tuned from zero during initial warm restart tuning, and further for cold starts. If only clearing air, the duration would be fixed. ;)

Priming Delay is intended to delay the injector prime if necessary to allow the fuel pump to bring the system to stable pressure. Neither clearing air nor delay for pressure should be required in most systems. Pre-start added fuel by priming is a different matter for tuning.
PSIG - Thanks for the reply. Have set the pulse width to "0". Don't think any additional fuel is needed.

Regarding the spark igniters, spark igniter schematic:
Spark Igniter wiring.png
Spark Igniter wiring.png (1.49 MiB) Viewed 332 times
Here is the OEM testing procedure:
(202.18 KiB) Downloaded 4 times
There should definitely be 12 VDC n the B/W wire to ground. This is the wire from the ignition system. Same with the Y/Bu and Bu/Y wires from the coils. The "Y" and "Bu" wires going to the ECU are the kicker, should be a ground/no ground scenario.

Bit of a mystery, but works with the OEM ECU. Befuddles the heck out of me. This is why I am thinking the setting has to be GOING HIGH.
Do your thing. Thanks for the schematic, but it doesn't show the sources of the wires or a legend, so I have no idea what they are supposed to be doing (GND, Signal, coil1(-), coil2(-), etc). I'm not saying you're wrong, and it's probably a terminology thing lacking of info on my end. Keep going!
Connected the new scope to the right spark igniter wiring. The positive went to the ECU wire and ground to the chassis. Don't know quite what I was looking at and have to spend a bit of time with the new scope to get familiar with it, but have a pic of the spark igniter trace, think so anyway. Tried a trace from the coil wire into the spark igniter, no joy.

Here is a picture of the trace, I'm hoping PSIG will chime in:
Spark Igniter Trace 2.JPG
Spark Igniter Trace 2.JPG (138.49 KiB) Viewed 294 times
From what I have read this scope trace is indicating that the coil is charging on the falling edge, and sparks on the rising edge(?). I also note the dwell time is approximately 10 ms (?).

The info I refer to is from Performance Fuel Injection Systems by Matt Cramer and Jerry Hoffman, page 102. this is a snapshot of two examples of different ignition module signals and coil current:
Info on Firing .JPG
Info on Firing .JPG (163.08 KiB) Viewed 294 times
The above info leads me to believe that I need to set the spark setting to GOING HIGH, or do I have it backwards. Open to very constructive comments.
Rednaxs60 wrote:
Fri Nov 25, 2022 12:47 am
Here is a picture of the trace, I'm hoping PSIG will chime in:
Spark Igniter Trace 2.JPG
Thanks for the schematic. It is now appears the harness wires for driver 1-2 are:
  • G: chassis ground
  • Y-Bu: coil1-2 negative
  • Bl/W: +12V
  • Y: ECM trigger signal
Your 'scope image appears to be of the coil(-) voltage, not the signal voltage. Confirm that you were probing the G (ground) and Y-Bu (coil(-) coil 1-2) or Bu-Y (coil(-) coil 3-4) wires?

To test signal, you would probe the G and Y wires for driver 1-2, or G and Bu wires for driver 3-4. If you have noise on your square wave from coil firing, test chassis ground or battery(-) to Y or B.
Rednaxs60 wrote:
Fri Nov 25, 2022 12:47 am
The info I refer to is from Performance Fuel Injection Systems by Matt Cramer and Jerry Hoffman, page 102. this is a snapshot of two examples of different ignition module signals and coil current:Info on Firing .JPG
That info is of course accurate, but depends on the 'scope data being the square-wave signal voltage, comparing to coil activity. You can use either coil current or coil voltage (as in your image) to compare the going-high-or going-low signal when the coil fires. The drop towards ground in your image is coil dwell beginning, and the large positive spike is coil firing at end-of-dwell.

There are yet more ways to determine this, such as testing continuity. Disconnect the coils (only) and test the driver with a multi-meter — does Y-Bu conduct (continuity) to G when manually-applied signal is high, or low? Alternatively test with a 'scope while cranking.

Not knowing coil specifications; 10ms is reasonable, assuming the battery is likely at low-voltage, and the ECM is correcting with longer dwell than typical.
PSIG - thanks for the reply. Was using the "Y" wire and grounding to chassis of numbers 1 and 2 spark igniter. Tried the "Y/Bu" wire as well, no joy.

Read the setup and instruction manual for the scope last night. Will test all wires of the spark igniter today. More to follow.

Will do the test on the spark igniter that you recommend. Will take out the plugs as it is easier on the battery.

Intend to setup for timing today as well.

Edit: Mentioned in another post that I would look at the wiring trace for Arduino pin #A15. Did this today. It goes where it is supposed to - most of you had probably figured this out. For myself, it's an understanding of the board nomenclature and associating what I see with where it goes, especially pin allocation.

In this case, hadn't thought about how the pins were labelled/numbered and what the numbering meant, such as pin A15. This is an Arduino PIN number not a board PIN number. A small, but important issue I think. Just a thought.
Did some testing this afternoon to confirm spark igniter scope wave form, and engine timing.

Engine idle dwell is 15 degrees using father's Snap-On timing light. This confirms what I saw on the tach/dwell meter of 14 degrees - very specialized calibrated equipment.

Had another go at the spark igniter scope wave form. Much like the other day, but quite clear:
Spark Igniter Trace 3.JPG
Spark Igniter Trace 3.JPG (145.28 KiB) Viewed 194 times
This picture shows the discharge of the coil through the plug:
Spark Igniter Trace 5.JPG
Spark Igniter Trace 5.JPG (146.7 KiB) Viewed 194 times
As PSIG mentioned, 10 ms is probably a good starting point. The first wave form confirms this.

My perspective regarding the spark igniters is that the coil charges when the ECU rounds the spark igniter allowing the system voltage to charge the coil. After ~10 ms the ECU stops the ground and the coil fires through the spark plug.

Did some research and I looked into the question of GOING HIGH/LOW in the MS manual. GOING HIGH is used when the coil charges on the rising edge of the signal, so I would expect that when the coil charges on the falling edge it is called GOING LOW - rhetorical question, jump in here. :D
More reading and research regarding the spark igniter unit GOING HIGH or GOING LOW. Speeduino forum thread https://speeduino.com/forum/viewtopic.php?t=1174 is a good read. PSIG's post 18356 on this thread mentions: "The fastest way to fry a driver is to forget Speedy is not an MS. ;) In Speeduino, Going High/Low setting is what it does to fire the coil, and output is not inverted. Your IGBT would use going HIGH to begin dwell (make the IGBT conduct coil power), and :arrow: going LOW to stop dwell and fire the coil. If the driver was already hot, then note in the datasheets that at 110° and with proper heat sinking it will only handle less than 4 amps at 14V max. :shock: So, keep it cool. Other causes for toasting could be excessive dwell (for that coil), excessive driver gate resistance, lack of sufficient heat sinking, and a slew of other common and known issues. Hope that helps."

This would indicate that my setup would need to be GOING HIGH since the coil fires through the spark plug when the ECU removes the ground to the spark igniter unit.

Going looking for more info.
PSIG - have been doing more reading and searching for the "holy grail" so to speak. The wave forms are that of the coil. More probing to be done to get more answers. I know I'm delving into this probably a bit much, but it is interesting information that I will probably never use again. Good for a game of trivial pursuit, or not.
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