What Causes Spark Plugs to Fail Frequently?

[SanSteven]

Common reasons for spark plug failure include the following: Improper 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 quenching effect of the electrodes. Although a spark occurs, it is weak, making ignition of the mixture difficult. Conversely, if the gap is too large, the ignition voltage provided by the system may be insufficient to generate a spark between the electrodes. Cracked spark plug skirt. High-voltage current can arc through the crack, causing leakage and preventing a spark at the electrodes. Electrode carbon buildup. Excessive carbon deposits on the spark plug can cause the center electrode to leak current to the surroundings instead of jumping to the side electrode, resulting in a short circuit and no spark. This can further damage the insulator and render the spark plug unusable. Electrode damage. Prolonged electrical erosion from sparks or chemical corrosion from combustion gases can cause the electrodes to break or detach, preventing sparking. Low insulation resistance of the spark plug. This condition reduces the ignition voltage applied to the spark gap, weakening the spark or completely disabling ignition. Short circuit in high-voltage wiring. If the ignition coil-to-distributor high-voltage wire leaks, the entire engine may fail to start. If the distributor-to-spark plug wire leaks, one cylinder's spark plug may not fire. Eroded platinum contacts. This can prevent all spark plugs from firing, making the engine unable to start or run normally. Symptoms of spark plug failure include: Difficulty starting the car, whether cold or hot, often requiring multiple attempts. Engine shaking during operation. Reduced power output, noticeably weaker than usual. 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 each spark plug, ensuring the area is free of debris like leaves or dust. Insert the new spark plug into the hole, hand-tighten it a few turns, then use the socket to secure it. Reinstall the high-voltage wires in the correct firing order and reattach the cover. Replacement interval: Under normal maintenance, spark plugs should be replaced every 40,000–60,000 km. However, this may vary by brand and engine type, so consult the owner's manual for specifics.