What Causes Spark Plug Failure?

[JadeLee]

Common causes of spark plug failure include the following: Incorrect spark plug gap adjustment. If the gap is too small, it not only limits the contact area between the spark and the air-fuel mixture but also suppresses flame kernel growth due to the flame-quenching effect of the electrodes. Although a spark occurs, it is weak, making it difficult to ignite the mixture. If the gap is too large, the ignition voltage provided by the ignition system may be insufficient to create a spark between the electrodes. Cracked spark plug skirt. High-voltage current leaks through the crack, preventing sparking at the electrodes. Electrode carbon buildup. Carbon deposits on the center electrode cause leakage to the surroundings instead of sparking to the side electrode. Excessive carbon buildup can short-circuit the spark plug, preventing it from sparking and eventually burning out the insulator, damaging the spark plug. Electrode damage. Prolonged electrical erosion from sparks or chemical corrosion from combustion gases can cause the electrodes to break or detach, preventing sparking. Low spark plug insulation resistance. This weakens the ignition voltage applied to the spark gap, resulting in weak sparks or a complete loss of ignition function. Short circuit in high-voltage wires. If the high-voltage ignition wire from the ignition coil to the distributor leaks, the entire engine may fail to start. If the wire from the distributor to the spark plug leaks, the spark plug in one cylinder may not spark. Burnt platinum contacts. This can cause all spark plugs to fail to spark, preventing the engine from starting or running normally. Symptoms of spark plug failure include: Difficulty starting the car, whether cold or hot, often requiring multiple attempts. Engine shaking, noticeable while driving. Reduced power, with a noticeable lack of acceleration compared to normal conditions. Increased fuel consumption. Engine stalling. Failed emissions tests. Faulty spark plugs should be replaced promptly. The replacement steps are as follows: Open the hood and remove the engine's plastic cover. Disconnect the high-voltage wires, marking each cylinder's position to avoid confusion. Use a spark plug socket to remove the spark plugs one by one. Check for debris like leaves or dust around the area and clean it thoroughly. Place the new spark plug into the spark plug hole and hand-tighten it a few turns before using the socket wrench. Reinstall the high-voltage wires in the correct firing order and reattach the cover. Spark plug replacement interval: Typically, spark plugs should be replaced every 40,000–60,000 km under normal maintenance conditions. However, this may vary depending on the brand and engine type, so refer to the owner's manual for specific recommendations.