How long does the empeg take to respond to the ignition line going off? Could you keep cranking the car and see whether the empeg goes off?

I just went out to the car and tried it. The behaviour is exactly as you describe -- the empeg comes up when I turn the key to the RUN/IGN position, and then drops out again when I crank the engine. There's a really small pop when the empeg comes up, and then a much larger one when the accessory line drops out.

The empeg drops out pretty much instantly when I crank the engine.

While I was out there, I took some photos.