What are the symptoms of bad spark plugs?

[ArcherAnn]

Symptoms of bad spark plugs: 1. Difficulty starting and stalling for no reason. A clear symptom is difficulty in starting the car. Bad spark plugs can lead to insufficient ignition energy, or even failure to generate high voltage electricity, preventing the creation of sparks to ignite the fuel-air mixture in the cylinder, making it naturally impossible to start the car. Even if the car can start, it may suddenly stall. 2. Lack of power and excessive exhaust emissions. Bad spark plugs cause incomplete combustion of the fuel-air mixture in the engine, resulting in insufficient power. The replacement interval for spark plugs generally ranges from 20,000 to 100,000 kilometers, varying with different materials. 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 replacement. For 4-cylinder models, if one spark plug is damaged, it is recommended to replace all four together, as replacing only one may affect overall performance.