ping vs knock

Actually, ping is a common term to indicate what is officially knock. It sounds much more like "knock" to me than as "ping," but anyway.

However, the engine people refer to wild ping when the mixture is ignited at the wrong time and place by surface deposits. It is characterized by one or more erratic sharp cracks. It is a heart stopping sound for the loving Miata owner, I can tell you.

Depends. Normally retarding timing reduces knock. However, retarding timing by 340 degrees may have an opposite effect.

In addition, a kind of knock caused by ignition by hot surface deposits is not controllable by reducing spark ignition advance. (If the surface deposits are really, really hot, I assume. Otherwise reducing advance would surely help, I would think.)

Leon