What are the symptoms of a faulty car spark plug?
2 Answers
Spark plug failure manifests in the following ways: Difficulty starting the car, with both cold and warm starts being problematic, often requiring multiple attempts. Engine vibration occurs while driving. Reduced power output, with noticeably weaker performance compared to normal conditions. Increased fuel consumption. Engine stalling. Failed exhaust emissions. Common causes and diagnosis of spark plug failure: Typical situations that cause spark plugs to malfunction include: Incorrect spark plug gap adjustment. A gap that is too small limits the contact area between the spark and the air-fuel mixture, while also suppressing flame kernel growth due to the electrode's flame-quenching effect. Although sparking occurs, the spark is weak, making it difficult to ignite the mixture. Conversely, a gap that is too large may prevent sparking if the ignition system cannot provide sufficient voltage. Cracked spark plug skirt. High-voltage current leaks through the crack, preventing sparking at the electrodes. Carbon buildup on the electrodes, causing current leakage from the center electrode to the surroundings rather than to the side electrode. Excessive carbon deposits can short-circuit the spark plug, preventing sparking and potentially damaging the insulator. Damaged electrodes. Prolonged electrical erosion from sparks or chemical corrosion from combustion gases can cause electrodes to break or detach, preventing sparking. Low insulation resistance of the spark plug. This reduces the ignition voltage applied to the spark gap, weakening the spark or completely disabling ignition. Short circuit in the high-voltage wires. For example, 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 the spark plug can prevent sparking in one cylinder. Burnt platinum contacts. This can cause all spark plugs to fail, making the engine unable to start or run normally. Faulty spark plugs should be replaced promptly. The replacement steps are as follows: Open the hood, remove the engine's plastic cover, and 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, ensuring the surrounding area is free of debris like leaves or dust. Insert the new spark plug into the hole, hand-tighten it a few turns, and then use the socket to tighten it further. Reinstall 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. However, this may vary depending on the brand and engine type, so consult the owner's manual for specific recommendations.
When my car's spark plugs went bad, driving felt really unpleasant. It took several minutes of turning the key to start the engine, which shook like an earthquake, especially at red lights when the seats vibrated. When accelerating, even flooring the gas pedal had little effect—the car crawled sluggishly uphill and struggled, while fuel consumption suddenly spiked. Previously, a full tank could last 400 kilometers, but now it barely reached 350. Even worse, black smoke sometimes came from the exhaust, with a strong gasoline smell, forcing frequent trips to the repair shop. These symptoms were all related to incomplete combustion, and prolonged neglect could damage the engine. I remember the first time it happened on the highway—the car suddenly jerked and nearly stalled, scaring me! Since then, I've made sure to check the spark plugs regularly.
