Steps for installing spark plugs: First, open the hood, lift the plastic cover of the engine, remove the high-voltage distributor wires, and mark each cylinder's position to avoid confusion. Then, use a spark plug socket to remove the spark plugs one by one. While removing them, check for any leaves, dust, etc., on the outside and ensure they are thoroughly cleaned. Next, place the new spark plug into the spark plug hole, hand-tighten it a few turns, and then use the socket to tighten it further. Finally, reinstall the removed high-voltage distributor wires according to the firing order and secure the cover. Location of spark plugs: Spark plugs are installed on the side or top of the engine. In earlier models, spark plugs were connected to the distributor via ignition wires. However, over the past decade or so, most car engines have been updated to feature ignition coils directly connected to the spark plugs. 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. A discharge channel forms in the gap, leading to 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 engine's combustion chamber.
