What are the symptoms of a bad spark plug?
4 Answers
Symptoms of a bad spark plug: 1. Reduced power: When a car's spark plug becomes excessively clogged, it affects the resistance efficiency, leading to insufficient spark plug power; 2. Difficulty starting the car: After the spark plug is damaged, it becomes difficult to coordinate with other parts of the car, making it hard to start the vehicle; 3. Increased fuel consumption: When the spark plug is damaged, the car's ignition system is also affected, resulting in higher fuel consumption. The replacement interval for spark plugs is generally between 20,000 to 100,000 kilometers, varying depending on the material of the spark plug. Ordinary nickel alloy spark plugs should be replaced approximately every 30,000 kilometers, while better iridium or platinum spark plugs can last 60,000 to 80,000 kilometers before needing replacement.
A faulty spark plug is indeed troublesome, and the car's performance will be noticeably off. Starting the engine becomes particularly difficult—it takes a long time to turn the key before the engine fires up, and it feels like the engine is struggling. At idle, it's even worse—the car shakes violently, especially when stopped at a red light, making the whole car vibrate uncomfortably. Acceleration feels weak, stepping on the gas pedal is like stepping on cotton, and climbing hills becomes a challenge with sluggish speed, making overtaking difficult. Fuel consumption also increases significantly—previously, a full tank could cover 500 kilometers, but now it might drop to 400, wasting extra money on gas. The exhaust pipe may sometimes emit black smoke or shake more intensely. If misfiring occurs, the entire engine runs unevenly, potentially damaging other components like ignition coils or the catalytic converter. If you encounter these symptoms while driving, it's best to visit a repair shop immediately for inspection. Spark plugs typically last 20,000 to 30,000 kilometers—don't delay to avoid bigger problems.
I remember one time when my car had a really hard time starting. I had to turn the key for a long time before the engine finally roared to life, and later found out it was due to spark plug issues. The most obvious symptom was severe idling vibration—when stopped at a red light, it felt like the car was doing a swing dance, with the steering wheel shaking so much it made my hands numb. Acceleration was sluggish too; even with a heavy foot on the gas, the RPMs climbed painfully slow, making highway overtaking risky and requiring patience for speed buildup. Fuel consumption skyrocketed—my usual monthly fuel cost of 500 yuan now increased by over 100. Misfires made the engine shake even more noticeably, especially when going uphill. Worn spark plugs can also affect emissions, potentially causing a failed annual inspection. For regular maintenance, check the replacement interval recommended in the manual and don’t delay when it’s time to change them—ensuring both driving safety and efficiency.
Common symptoms of spark plug failure include: Difficulty starting, the car takes a long time to move after turning the key; Unstable idle, noticeable engine shaking; Lack of power during acceleration, sluggish response when pressing the throttle; Increased fuel consumption, using more fuel for the same distance. In severe cases, misfiring may occur, causing the car to run unevenly with vibrations. All these affect daily driving, and early inspection and replacement can prevent bigger troubles.
