What are the symptoms of a bad spark plug in a car?
3 Answers
The symptoms of a bad spark plug in a car are: 1. Difficulty starting and unexplained stalling: Insufficient ignition energy fails to generate high voltage, preventing the ignition of the air-fuel mixture in the cylinder, making the car unable to start. Even if it starts, it may suddenly stall; 2. Lack of power and excessive exhaust emissions: This leads to incomplete combustion of the air-fuel mixture in the engine, resulting in insufficient power, black smoke from the exhaust pipe, and the emission of harmful substances that have not been fully burned, causing excessive exhaust emissions. If the spark plug electrode shows signs of melting, erosion, rounding, or if the insulator has scars, cracks, or carbon deposits, it indicates that the spark plug is damaged. Although the car can still be driven for a short time, it is advisable to replace the spark plug with a new one promptly.
As someone who frequently repairs cars, I've noticed that a faulty spark plug can cause quite a few symptoms in a vehicle. Starting the engine becomes particularly difficult, especially in cold weather, requiring several turns before it fires up. Once started, the idle becomes noticeably shaky, almost like it's dancing. When driving, acceleration feels weak, and even climbing a small hill makes the car struggle. Fuel consumption also quietly increases because the faulty spark plug leads to incomplete gasoline combustion, and you might even see black smoke or a burnt smell from the exhaust. If left unattended for long, the car is prone to stalling at high speeds, with even more unstable power output. I recommend checking or replacing spark plugs every 20,000 kilometers to avoid further engine damage. Regular maintenance can save a lot on fuel costs and extend the engine's lifespan—saving money and giving peace of mind.
Last time my car had a problem, it turned out to be faulty spark plugs. Starting the car was particularly slow, more noticeable in hot weather, and the engine jerked while driving, with acceleration as sluggish as a crawling snail. The dashboard warning light came on, displaying an engine fault code. The idle was unstable with noticeable body vibration; stepping on the gas pedal felt weak, making overtaking difficult. Even worse, fuel consumption soared—I usually get 500 kilometers per tank, but at that time, it barely exceeded 400. There was also a slight odd smell from the exhaust. After replacing the spark plugs, everything returned to normal—a simple fix solved the problem. It's important to develop a habit of regular maintenance, checking the condition of the spark plugs. If any abnormality is detected, stop and inspect immediately to prevent being stranded on the roadside.
