Why does the X-Trail idle after replacing the spark plugs?

[VanCooper]

After replacing the spark plugs, the X-Trail may idle because the cylinder wires were broken or damaged during the replacement, causing abnormal ignition, or due to the installation of spark plugs of a different model. Composition of spark plugs: Spark plugs are a crucial component of the gasoline engine's ignition system. They introduce high voltage into the combustion chamber and generate a spark across the electrode gap to ignite the combustible air-fuel mixture in the cylinder. Working principle of spark plugs: Under high voltage, the air between the center electrode and the side electrode of the spark plug 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 and forming a discharge channel, resulting in a "breakdown" phenomenon. At this point, the gas becomes a luminous body, known as a "spark." Along with the heat expansion, a "crackling" sound is also produced. The temperature of this electric spark can reach 2000-3000°C, which is sufficient to ignite the air-fuel mixture in the cylinder's combustion chamber.