What are the symptoms of a failed spark plug?
2 Answers
The symptoms of a failed spark plug are: 1. Lack of power when accelerating; 2. Car shaking when idling at a red light; 3. Difficulty starting or sudden engine stall. The causes of spark plug failure are: 1. Long-term accumulation of carbon deposits without cleaning; 2. Neglecting the cleanliness of the spark plug's exterior; 3. Over-tightening during installation; 4. Exceeding the spark plug's service life. Spark plugs, also known as firing plugs, function by discharging the high-voltage pulse electricity sent from the high-voltage wire, breaking down the air between the two electrodes to generate an electric spark, thereby igniting the air-fuel mixture in the cylinder. Spark plugs are categorized into: 1. Standard spark plugs: The insulator skirt is slightly recessed into the shell end face, with the side electrode outside the shell end face; 2. Insulator-protruding spark plugs: The insulator skirt is longer, protruding beyond the shell end face; 3. Seat-type spark plugs: The shell and threaded portion are made conical.
When spark plugs fail, the car becomes difficult to start, often requiring several turns of the key before it ignites. At idle, the engine shakes constantly, making it feel like sitting in a massage chair while watching a movie. Acceleration lacks power, with a sluggish response when stepping on the gas, struggling even on small inclines. Fuel consumption spikes—last month, I had to refuel twice more than usual, costing an extra hundred bucks. The noise increases, producing a 'thumping' sound, and black smoke comes out of the exhaust, emitting a pungent odor. If ignored long-term, the engine may stall or experience severe shaking, which is very dangerous. I learned this the hard way when my car broke down mid-journey, nearly causing a rear-end collision. Now, I check regularly and replace the spark plugs every 40,000 to 50,000 kilometers, and the car runs much smoother. Replacement isn’t complicated—a repair shop can handle it in half an hour. Don’t skimp on this expense.
