Pinging in an engine is the result of the air and fuel mixture within an engine cylinder igniting incorrectly, explains Cars Direct. This may be caused by using gasoline with an insufficient octane rating, carbon buildup within the cylinder itself or improperly functioning spark plugs.
When the fuel/oil mixture within an engine cylinder combusts, it normally does so in a progressive fashion rather than igniting all at once. This allows the force of the ignited fuel to provide controlled pressure on the piston, resulting in even thrust. If the ignition stutters or the gas ignites all at once, this creates a pinging sound and puts undue stress on the piston and cylinder, reducing performance and decreasing the life of the engine.
High-octane gas is designed to prevent preignition of the air/fuel mixture. Using a higher-octane gas than normal can reduce pinging. Carbon buildup on the cylinder wall can also cause improper ignition and pinging. All U.S. gasoline contains detergents. Adding a detergent to fuel often helps clear out accrued deposits; additive detergents can be found at automobile supply stores. Faulty spark plugs can also cause improper ignition. If pinging persists, visit a mechanic to verify all spark plugs are in proper working order.