
diesels don't have spark plugs - the pressure in the cylinder is sufficient to cause ignition.
if under stress, like say a high state of tune, or due to wear, (for example the piston rings wearing) the engine oil in the sump, finds it's way into the pistons and being remarkably similar to diesel oil... it runs on it's own oil, which isn't regulated like the diesel fuel... so it runs away with itself
or 'diesels'
( , Thu 12 Nov 2020, 20:13, Reply)

youtube.com/watch?v=TS9j3TKsmIU
At first I thought that it was the dyno blowing the smoke, but now I’m not so sure.
( , Thu 12 Nov 2020, 20:28, Reply)

Explains why it increased over time.
I've only seen petrol engines dieselling, for different reasons.
( , Thu 12 Nov 2020, 21:07, Reply)

Your only hope is to either stuff something in the air intake and run away, or to apply whatever brakes they are... and run away.
( , Thu 12 Nov 2020, 22:20, Reply)