What is the Function and Working Principle of Spark Plugs?

[AmeliaLee]

Spark plugs function and working principle: The ground electrode of a spark plug is connected to the metal shell, which is threaded into the engine block via the cylinder head. The insulator primarily serves to isolate the metal shell from the center electrode. The terminal nut is the part of the spark plug that contacts the high-voltage coil. When current passes through the terminal nut and the center electrode, it ionizes the medium between the center electrode and the ground electrode, generating a spark to ignite the air-fuel mixture in the cylinder. Spark plug replacement intervals: Under normal maintenance conditions, replacement is recommended after driving 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's advisable to follow the owner's manual. The following standards can serve as a reference for maintenance replacement: Platinum spark plugs should be replaced at 40,000 kilometers, standard nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs at 60,000 to 80,000 kilometers.

[RubyLee]

I drive a lot and feel that spark plugs are really a critical component. In a gasoline engine, they are mainly responsible for igniting the air-fuel mixture, allowing the engine to generate power. Simply put, when you start the car, the ignition system sends high-voltage electricity to the spark plug, creating a small spark between the two electrodes, which ignites the fuel precisely when the piston compresses it, driving the engine. If the spark plug fails, the car won't start or will idle unevenly. Last time I replaced mine, I noticed that old, carbon-fouled electrodes can weaken the spark, causing engine shaking and increased fuel consumption. Regularly checking the spark plug gap and replacing them can keep the engine running smoothly, extend its lifespan, and avoid the embarrassment of breaking down, especially before long trips—it's best to check them.

[McLilliana]

I think the working principle of spark plugs is quite cool. They receive high-voltage electricity from the coil and generate a spark between the electrodes within microseconds, igniting the compressed gasoline-air mixture. Their effectiveness relies on the precise timing of this electrical spark, ensuring each engine cylinder operates on schedule, improving performance and fuel efficiency. I once modified mine and found that the material of the spark plug makes a big difference—for example, platinum ones are more durable. When driving, if you notice delayed ignition or sluggish acceleration, it might indicate a problem with the spark plugs. It's advisable to clean or replace them regularly; otherwise, reduced engine efficiency can lead to wasted fuel and a poorer driving experience.

[Bennett]

I figured out spark plugs when I was young—they're the heart of an engine, specifically responsible for igniting the combustion process. The working principle is straightforward: high-voltage current travels from the ignition wire to the electrodes, jumping a spark between them to ignite the air-fuel mixture, driving the piston movement. If spark plugs are old or heavily carbon-fouled, the spark weakens, making the car struggle to run and possibly causing misfires. I’ve replaced them many times and found that incorrect gaps or mismatched models often lead to engine vibrations, compromising driving safety. Maintenance is simple—just clean the electrodes—but don’t delay too long to prevent engine degradation.