Throttle Actuators on engine shutdown: self-check?

[macaddict111]

Hey all! There's absolutely nothing wrong with my Z. I'm an electrical engineer and love to know all about this car I recently bought, and had a "curiosity question".

I noticed early on that the ECM definitely "does something" right after shutting the engine down. The electronic throttle system always produces a frequency while the engine is running (that digital mid-frequency hum/whir from the throttle/VVEL actuators, likely due to Pulse Width Modulation). Right when you shut the engine down, the frequency continues for a bit (probably because it doesn't just shut the throttles immediately), and then you can hear the system "moving around" a bunch, with some associated clicking/clunking for about 3 seconds, and then it goes silent.

I absolutely LOVE hearing that. It makes my nerdiness go insane. haha

Just curious, does anybody know exactly what it's doing here? Is it just doing a self check of the actuators, or maybe a calibration/linearization? Or perhaps it's doing something to make the engine happier while it sits unused (maybe like my Z tucking itself in? haha)