How Many Spark Plugs Should Be Replaced at Once?
2 Answers
Automobile spark plugs should be replaced four at a time, meaning all of them should be changed. Theoretically, even if you replace just one with the same brand and model, the discharge gap and resistance of the new and old spark plugs will differ. Not replacing all of them can lead to issues such as engine shaking, difficulty in acceleration, and increased fuel consumption. This is because differences among spark plugs cause variations in ignition timing and energy, resulting in an imbalance in power among the four cylinders. Currently, the common electrode materials on the market include copper, nickel alloy, platinum, and iridium. The electrical conductivity of these metals increases from left to right, while the voltage required for ignition decreases from left to right. Therefore, precious metal spark plugs place less load on the engine and are beneficial for reducing fuel consumption.
I see there are quite a few car-related questions, like how many spark plugs to replace. Actually, it depends on how many cylinders the car's engine has. Most regular sedans have 4 cylinders, so you replace 4 spark plugs; if it's an SUV or sports car, it might have 6 cylinders, then you replace 6. Why replace all? Because old spark plugs wear unevenly, affecting acceleration and fuel efficiency. Replacing just a few new ones won't help and may cause power imbalance. When I maintain my car, I replace the whole set every 40,000 to 50,000 kilometers, costing a few hundred yuan, which saves hassle and improves fuel economy. If you're unsure about the number of cylinders, check the owner's manual or ask a mechanic to avoid wasting money.
