[JHolland]

Might sound stupid to some, but with sync I am not burning up my coils (wasted spark) with a duty cycle double what they need to run the engine, one set of coils is the cost difference between the two ecu choices. Being an aircraft solution, weight is limited so choosing heavy coils to increase heat dissipation and life is not an option when the existing coils might work fine if operated properly.

Try some different coils - I have wasted spark setups on motorcycles running at 12k+ rpm and mounted directly above the engine. I also have car engines with wasted spark coils bolted directly to the cam cover, those are stock setups that are proven reliable over 20 years and millions of cars.

[apollard]

These engines are designed with a high priority on cost. It would be surprising if they used anything other than wasted spark, because the engine and emissions demands would not require it. For example, the Rotax 600 EFI uses only the crank wheel for timing and uses wasted spark. Lots of those running around now in the US north.

[usatracy]

done
https://youtu.be/RVaVhkZLjQY?si=KnobUBpQkvziOd6f

[PSIG]

I like the conceptual train you have going. First question when I watched the vid, was the relationship between the fixed crank angle of teeth, relative to the dynamic position of the MAP spike? While the MAP spike could be across multiple teeth, will/can you simply shift the cam signal point to a different tooth you find the spike at when running? I'm looking to verify my interpretation follows your concepts.

[usatracy]

Actually, I moved beyond all that, the system will soon figure out the crank tooth to map sensor on its own with no need to identify it and program it (for one and two cylinder engines). It will determine that on startup cranking and ignore the map sensor input after that, no need to watch it after we are synced up.

[apollard]

In a perfect world, no need to resync. Engines don’t live in a perfect world, but where voltage spikes and noise, both emf and power supply noise can cause bad signals momentarily. When your systems gets a bad read from the crank wheel, how will it know? You could be out of sync and never know.

It’s not uncommon to see sync loss on running engines. Even in my basic distributor setup, there are triggering problems, albeit very rare I see one on a log. Consider fault tolerance in your design.

[usatracy]

microsquirt uses this for map sensor, it syncs and doesnt need resync.

if your install is clean there is no need for resync

if you are getting resync, time to revisit your install.

anyhow, how to automate the pulse to cranktooth.

1 cylinder has one map pulse
8 cylinder has eight map pulses

1 cylinder
crank the engine, identify the pulse to the crank tooth via the ecu, engine starts, record that crank tooth to the eeprom for future starts.

more than 1 cylinder, crank the engine, identify all the pulses, record the pulses to the eeprom, set one of the pulses as the crank pulse

if engine starts mark the other pulses in eeprom as invalid, mark the correct one as the pulse to use for future starts.

if engine fails to start

pause for a predetermined time, then crank again

the last pulse attempted will be marked invalid and the next valid test pulse will be used

repeat until engine starts.

the valid pulse crank tooth will be recorded in eeprom.

to erase the setting turn ecu on and off three times based on some programmed method
( eg on >5 seconds with no crank attempt then off, 3 times, clears the eeprom)

[usatracy]

https://youtu.be/A74UCkT9VYE?si=1HOudQ_pWGbspYxM

https://youtu.be/M9Xo5SgIehg?si=vxn7SXOhZdyJ6_ms

[usatracy]

https://youtu.be/fbj8ixhUTao?si=fFkWdSfS4rtpFEdF

How to make sure your electronics are protected, ban other electronics lol

[JHolland]

if your install is clean there is no need for resync
if you are getting resync, time to revisit your install.

You make it sound easy but I've designed OEM ECUs and been through the whole type approval process, there is an awful lot of testing for EMC for both immunity and radiated emissions. One PCB trace the wrong length or a badly routed wire and you can have problems. I was once flown out to Detroit because a customer was failing EMC because they had changed the length of a wiring harness after the ECU had been type approved.
Even with all the testing there have been incidents of Jeeps not starting when parked under power lines and vehicles misfiring when passing radar stations.