MicroSquirt.com read only forum (Jan.15,2018)

Here some research results from ignition:

I have build up an test bench for MSing my Moto Guzzi (V2 90 degrees).

I just connected two Bosch blue coils (about 3.2 Ohms) to the ignition section, applied a spark plug each and started with an idle speed of about 700 rpm. Everything looked fine.

But when I increased the rpm I lost connection to the MS beyond about 2500 rpm and the MicroSqiurt (software) quits running. Adding a 10 NF capacitor from the power transistor VB921 to ground (following to Bruce's recommendation in his sticky 'driving ignition coils..') helped up to 3500 rpm. Beyond that point I had the same effect (MS just quits running).

In short, the best result is to shield the ignition drive wires. I did it by wrapping 2-3 layers of an aluminium foil (just have a look into your kitchen) around the wires and connect the shield to ground.

After that I could remove the capacitors without any negative effect and the ignition runs up to 8000 rpm (limit of my test bench).

tubefan

tubefan wrote: In short, the best result is to shield the ignition drive wires. I did it by wrapping 2-3 layers of an aluminium foil (just have a look into your kitchen) around the wires and connect the shield to ground.

After that I could remove the capacitors without any negative effect and the ignition runs up to 8000 rpm (limit of my test bench).

tubefan

This is excellent!! Well done!!

You are absolutely correct in shielding the ignition drive wires. As mentioned before, the whole MS setup is very compact and noise coupling in the wires can be of concern. The ignition drive wires are the worst offender, they switch up to 7.5 amps each and can cause all sorts of noise. Running them in their own shielded "conduit", along with the injector outputs, can substantially reduce noise injection back into the tach circuit.

This is "sticky" material for sure Good job!

- Bruce

If I want to go a step further than the aluminum foil and use actual shielded wire, such as that available from DIYAutotune (though that's only 20gauge maybe not enough for the ignition wire??), are there pins available to attatch to the wire for use in the Ampseal connector (and does it take a special crimper?) Also what should I attatch the shield to, nothing? Ground? If it needs to be attatched to ground is there any special needs for this ground, for example if I have the snubber capacitor right there by coil the should I not use the same wire to ground for the capacitor and the shield?
Thanks
Andy