Toro 303447 - Engine Knocking: Detonation

Detonation
An undesirable engine condition in which pockets of fuel start to burn at about the same time as
the spark plug fires.
Multiple pressure fronts collide
Sometimes called knocking, spark knock or pinging.
Causes large pressure differentials in the combustion chamber.
Can cause engine damage.
Causes
Increased compression
High temperatures
Lean fuel/air mixture
Advanced ignition timing
Lower octane fuels
Prevention
Remove any cause