For such a small part, a worn spark plug can cause some pretty big problems. Poor fuel consumption, misfiring, hard starting, and engine knocking – the humble spark plug can be the cause of all these problems and much more.
What is the purpose of a spark plug? What are the symptoms of bad spark plugs? How often do you need to change spark plugs? By understanding the role of your spark plugs and recognizing the signs of worn spark plugs, you’ll be rewarded with a boost in fuel economy and a smooth ride.
What Do Spark Plugs Do?
Before we delve into what spark plugs do, we need to briefly explain how an engine works, so you can understand the important role your spark plugs play.
An engine’s purpose is to convert gasoline into motion. This happens largely due to a process that goes on inside the engine called internal combustion.
Inside the engine, valves fill the cylinders with an air/fuel mixture which is highly explosive when exposed to a source of ignition. The pistons compress the air/fuel mixture, increasing the amount of potential energy. At the peak of compression, a spark plug creates an arc of electricity lasting approximately 1/1000 of a second, igniting the air/fuel mixture inside the combustion chamber. This creates an explosion that forces the piston back down to its starting position. The crankshaft turns this energy into rotational motion, and your car moves forward.
Spark plugs are one part of your vehicle’s ignition system, which also consists of electrical and timing equipment. They are made from material durable enough to ignite millions of times before wearing out. The voltage at the end of the spark plug can be anywhere from 20,000 to more than 100,000 volts.
We should note that you won’t find spark plugs in a diesel engine as they use higher compression ratios to create combustion instead of relying on ignition from a spark plug.
