When to Change the Spark Plugs in Your Vehicle?


Today's automakers claim the spark plugs in your new car or truck may not have to be replaced for up to 100,000 miles. However, that doesn't mean those plugs will be operating a peak efficiency at that distance or even half that mileage. It is always prudent to rely upon your judgment as the owner rather than blindly follow a manufacturer's hype. These small but mighty components of your ignition system play an important role in bringing your vehicle's engine to life as well as maintaining a smooth burn of the compressed air/fuel mixture while you drive. But, spark plugs reside in a world of high voltage and heat, and both can take a toll over time.

As the final link in the ignition process, a spark plug receives a high voltage burst from the battery or magneto based upon the type of engine. The center electrode of the plug passes an electrical current to the plug's tip that was amplified by the coil or magneto. Once the voltage at the tip exceeds the dielectric strength of the compressed air/fuel mixture, the spark ignites the gases creating an explosion that forces the engine's piston downward or away from the combustion chamber. For most engines, spark plugs typically require in excess of 20,000 volts to fire.

The transmitting of the electrical energy through the plug occurs on each firing cycle of the engine. For the vast majority of vehicles on the road today, this occurs on every other cycle (4-stroke) but some recreational vehicles use a 2-stroke engine that fires each time the piston reaches the top of the cylinder. Once an engine comes to life, the spark plug plays a major role as a heat exchanger. Although spark plugs create a burst of energy to ignite the fuel or gasoline, they do not create heat. Conversely, the firing end of the plug actually dissipates heat by pulling thermal energy away from the combustion chamber. This is why it is important to replace worn plugs with correct heat range. The temperature at the end of the plug must be kept low enough to prevent pre-ignition but high enough to avoid fouling.

There is a lot that goes on during each revolution of your vehicle's engine and the spark plugs are right in the middle of the action. Rather than wait for an advertised mileage number to be reached before you change your plugs, why not let your engine's performance be the guide. When a motor misfires, there is an increase in exhaust emissions that not only pollute the air but the raw fuel lost in the process lowers your gas mileage. If your engine becomes more difficult to start or you've noticed engine surging, it's time to take a look at the plugs to determine the cause of your engine's ignition problems. To learn more, visit the Technology section of the E3 Spark Plug's website, then use our Spark Plug Search feature or cross-reference guide to find the correct replacement plug for your vehicle.

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