Is it like a small knock? Or a knock like you know something is smaking in there? If it's the second one then your throwing a rod. If it does it in neutral then you can find out which one it is you can pull one spark plug at a time and see if it stops if it does then you know that's the one.

:edit: I don't know what ping is. :thinking:

Ohh and KAUAI KANE that book will not tell you what the hell that is.