What is the working principle of spark plugs?
3 Answers
The working principle of a spark plug is that the electrode of the spark plug generates repeated and continuous ignition pulses. The high-voltage pulse electricity breaks down the air between the two electrodes of the spark plug, creating a spark and generating an explosion to ignite the mixed gas in the cylinder, which then causes the engine to start running. Spark plugs are consumable items and need to be replaced regularly. The choice of spark plugs directly affects engine operation. When replacing spark plugs, many people only focus on the material and the number of electrodes, but in fact, the heat value of the spark plug is also very important. Choosing spark plugs with different heat values can easily affect engine output, and it is even possible for the spark plug to be directly damaged.
I've been repairing cars for a long time, and the core function of a spark plug is to convert high-voltage electricity into a spark to ignite the air-fuel mixture. The ignition coil amplifies the voltage and transmits it to the center electrode of the spark plug. There's a tiny gap between the center electrode and the ground electrode, and when the electrical spark jumps across this gap, it ignites the gasoline and air mixture in the cylinder, powering the engine. The key is that the spark must be timely and precise—for example, at high engine RPMs, the spark must keep up, otherwise, you'll get misfires, engine shaking, and a spike in fuel consumption. I've seen many cases of worn-out spark plugs where electrode erosion or excessive carbon buildup weakens the spark, leading to poor performance and black smoke. That's why regular replacement is crucial—every 30,000 kilometers, check the gap to ensure it's around 0.7mm, which can save a lot on fuel costs. Different spark plug materials vary in performance: standard copper plugs are cheap but don't last long, while iridium plugs are more efficient but pricier—choose based on your budget.
Last time my car had trouble starting, and after towing it for repairs, I found out the spark plug was faulty—it relies on the high voltage from the ignition system to create a spark between the center and side electrodes to ignite the air-fuel mixture, acting like a tiny lamp. The spark plug operates inside the engine's combustion chamber; when the piston compresses the mixture, the spark flashes, triggering instantaneous combustion to power the car. If this fails, causing delayed ignition or weak sparks, the engine may misfire or struggle to start—I’ve experienced those tough winter mornings when the car wouldn’t fire up. During routine maintenance, checking for carbon buildup is crucial, especially if using low-quality gasoline, which tends to leave deposits. Cleaning the electrodes or using a specialized tool to measure the gap is necessary. After replacing the spark plugs, I noticed a significant improvement in acceleration and even saved about 5% on fuel. Remember to replace them every three to four years, and opt for models with high-quality ceramic insulation for better durability.
