What Causes a Gasoline Engine Spark Plug Not to Fire?

[DelZoe]

Gasoline engine spark plugs may fail to fire due to damage or lack of electrical current. It is advisable to check whether the ignition wiring of the car engine is functioning properly. The spark plug is a crucial component of the gasoline engine ignition system. It introduces high voltage into the combustion chamber and generates a spark by jumping the electrode gap, thereby igniting the combustible air-fuel mixture in the cylinder. Under high voltage, the air between the spark plug's center electrode and side electrode rapidly ionizes, forming positively charged ions and negatively charged free electrons. When the voltage between the electrodes reaches a certain level, the number of ions and electrons in the gas increases like an avalanche, causing the air to lose its insulating properties. This creates a discharge channel between the gap, resulting in a 'breakdown' phenomenon. At this point, the gas forms a luminous body, known as a 'spark.' Along with thermal expansion, a 'snapping' sound is produced. The temperature of this electrical spark can reach 2000–3000°C, which is sufficient to ignite the air-fuel mixture in the cylinder's combustion chamber.