[fiveohpatrol]

You know the one. The weird knocking/clunking that you usually hear in an old chevy pickup when its trying to be shut off but wont shut off?

Its also the noise used as a sound effect in movies and cartoons when a car breaks down.

what causes this? an extreme lean condition? the engine rattling back and forth in the engine bay? or what?

I'm not having this problem, just heard it again today and started wondering what mechanically is going on to cause it.