Not getting spark from ignition coil test circuit

Question

I have a simple circuit setup with an N channel MOSFET switching ground to a two pin ignition coil. I am not getting any spark from the spark plug in the coil. Could someone take a look at the attached picture and let me know if there are any glaring issues?

Answer 1

1. 2.5V at the gate is probably not enough to make the MOSFET conduct well enough to generate a spark.
2. From what I find, it takes 4 milliseconds or more to "charge" a spark plug coil. You need a longer pulse.
3. If your circuit ever once produces a spark, it will die. There's no protection for the MOSFET.

Answer 2

The polarity of your battery is wrong and a typical good old ignition coil needs a capacitor of around 200 nF / 250 V across the switch for a powerful spark.

The secondary winding together with the internal capacitance has a resonance frequency. If you run the circuit without the extra capacitor on the primary side, the voltage rises too fast and the secondary resonance is not hit, which results in poor peak voltage.

In this circuit the capacitor must be placed between drain and source of the FET.

You need a FET, that can withstand 200 V, because the flyback voltage of the primary coil typically will be between 120 and 150 V peak.