Newbie: ignition only setup on a small 4-stroke single

[mfro]

It still only works with skip teeth = 36 (18=RPMx2, 0=erratic behaviour), although I double checked that I have disabled dual spark mode (I do in fact want to run wasted spark). Do you have an idea on how to fix this? Does it matter at all - what if I just leave it since it seems to work?

Answering myself here. Just realized I need to fix this. When skip teeth = 36 means 1 spark / 720°, it's pretty likely it will spark during exhaust stroke only instead of compression stroke with nothing to detect cam position.

Any ideas what else could be wrong with my setup (skip teeth = 18 not working)?

[grippo]

Could you post your msq ?

[mfro]

Could you post your msq ?

Yes, certainly. Appreciate any help on this.

Maybe I just don't see the wood for the trees, but I already spent several hours testing different settings without any clue.

[grippo]

The number teeth I saw in the msq was 38 - I'm guessing that was just a test change, but wanted to alert you to it.

The best way to fix this is to configure in dual spark mode. Then you can set single crank trigger wheel and you should get the correct rpm and one spark per rev. There is a lot of info on how to set this up, including with single cylinders. If you go to microsquirt.info and select dual spark in the left side sidebar, that will get you there. There is even more info on the link at the very end of this. If you want to go to 3.430 go (in the beta test section) there are special options for 1 cylinder and 2 cylinder (wasted) which take care of the dual outputs.

[mfro]

The number teeth I saw in the msq was 38 - I'm guessing that was just a test change, but wanted to alert you to it.

The best way to fix this is to configure in dual spark mode. Then you can set single crank trigger wheel and you should get the correct rpm and one spark per rev. There is a lot of info on how to set this up, including with single cylinders. If you go to microsquirt.info and select dual spark in the left side sidebar, that will get you there. There is even more info on the link at the very end of this. If you want to go to 3.430 go (in the beta test section) there are special options for 1 cylinder and 2 cylinder (wasted) which take care of the dual outputs.

I indeed tested different changes but wasn't aware I saved it. Sorry for that. I must have mixed up files during copying (I do not have internet in the workshop).

Thank you! I will look into this tonight. I already read the mentioned documentation until my brains striked but willing to do that again until everything works.

[mfro]

Tried this today. After a Microsquirt restart, everything works as advertised .

I again spent several hours on the suggested reading and think I now understand it. Just to be sure: with dual spark enabled, I need to connect IGN1 and IGN2 to the same coil. The manual seems to say on one place to do that with an OR gate, on another it implies both output can be just tied together.

I suppose with a microsquirt both outputs can be connected together?

Everything looking good so far, thank you. Are there any counters in Megatune/Tuner Studio that would help me to verify if my offsets are set correctly?

Out of curiosity: I still do not understand why skip teeth = M doesn't work?

[grippo]

What it says is that you can tie the outputs from the Bosch igniters (the large vertical chips tied to the large Al heat sink block) together, because they are designed to allow this, but some people remove these and use direct 0 - 5V outputs from the processor because they have their own logic level ignition drivers - often built into the coil. If this is the case you need to use a logic level AND or OR gate chip to tie them together, but if your coil is an ordinary 12V coil, then you can leave the Bosch drivers and tie IGN1, 2 wires from the Ampseal.

The best way to tell if your setup is correct is to disconnect the injectors and crank the engine with a timing light on it. If the setup is wrong so as to cause missed synchs or no rpm that will be obvious from watching the RPM gauge in TS. But the only way to tell if the ign timing is correct is with a scope or a timing light.

[800vtwin]

As you want to run wasted spark. Skip teeth should be 0.

And then change your trigger offset from 200 to -160 (negetive). trigger offset needs to be a negative value.

[grippo]

"As you want to run wasted spark. Skip teeth should be 0. "

This statement might be confusing. There is a skip pulse that has to do with skipping the first few teeth that come in during cranking (unrelated to wasted or not) and Skip_teeth which should never be 0 because it represents the number of teeth between tach pulses.

[mfro]

I have some progress to share:

ZZ07018FAE.jpg (30.32 KiB) Viewed 1191 times

After successful lathe testing, I managed to finish the generator/pickup part of the venture.

Getting closer now.