How to Test the Condition of Spark Plugs?

[Isaiah]

Spark plugs exhibit the following symptoms when they may be faulty: Difficulty in starting the car, both cold and hot starts are problematic, often requiring multiple attempts. Engine shaking, noticeable vibrations while driving the car. Lack of power, a significant decrease in performance compared to normal conditions. Increased fuel consumption. Stalling issues. Failed exhaust emissions tests. Common causes and diagnosis of spark plug failures: Several common issues can prevent spark plugs from functioning properly: Incorrect spark plug gap adjustment. A gap that is too small limits the contact area between the spark and the air-fuel mixture, and the flame kernel growth is suppressed by the electrode's flame quenching effect, resulting in weak sparks and difficult mixture ignition. Conversely, a gap that is too large may exceed the ignition system's voltage capacity, preventing spark generation. Cracked spark plug skirt. High-voltage current leaks through the crack, preventing sparks at the electrodes. Carbon buildup on electrodes, causing leakage from the center electrode to the surroundings instead of sparking to the side electrode. Excessive carbon deposits can short-circuit the spark plug, preventing sparks and damaging the insulator. Damaged electrodes. Prolonged electrical erosion from sparks or chemical corrosion from combustion gases can cause electrode breakage, preventing spark generation. Low insulation resistance of the spark plug. This reduces the ignition voltage applied to the spark gap, weakening or completely eliminating the spark. Short circuit in high-voltage wires. Leakage in the wire from the ignition coil to the distributor can prevent the entire engine from starting, while leakage in the wire from the distributor to a spark plug can prevent sparking in one cylinder. Burnt platinum contacts. This can prevent all spark plugs from firing, making the engine unable to start or run normally. Faulty spark plugs should be replaced promptly. The replacement steps are as follows: Open the engine hood, remove the plastic cover, and detach 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, ensuring the surrounding area is free of debris like leaves or dust. Insert the new spark plug into the hole, hand-tighten it first, then use the socket to secure it. Reattach the high-voltage wires in the correct firing order and replace the cover. Spark plug replacement interval: Typically, spark plugs should be replaced every 40,000 to 60,000 kilometers under normal maintenance conditions, but this may vary by brand and engine type. Always refer to the vehicle's manual for specific recommendations.