Spark Plugs Explained
Spark plugs have been around as long as internal combustion engines have. But as one of the smallest components of a car, the spark plug’s essential function is often overlooked. That is, until it stops working.
Without a spark plug, petrol engines cannot start nor accelerate or continue to run. Essentially, without your spark plug, your vehicle will likely never leave your garage.
In this article, we’ll take a closer look into how spark plugs work, including why they are so important, the best time to change your spark plug and the signs that your spark plug needs changing.
What are spark plugs?
As its name suggests, a spark plug is a component in your ignition system that creates an electrical spark that ignites the air-fuel mixture within your engine. In turn, this explosion puts the pistons in motion within your engine and produces the power to move your vehicle forward. It’s a crucial component in transferring the potential energy of gasoline into kinetic energy.
Generally, spark plugs are made from highly durable materials. They can withstand a continuous onslaught of explosions before wearing out or needing to be replaced. There are four main types of spark plugs:
- Copper or nickel: These are likely to wear out quicker than other types of plugs and they sit at the lower end of the product line.
Platinum: This spark plug has a platinum tip which offers a considerably longer lifespan than copper or nickel plugs. - Double platinum: As the name suggests, this spark plug has both electrodes coated with platinum making them longer-lasting and more efficient.
- Iridium: Most manufacturers these days will install these “extended-life” spark plugs at the factory. They’re only marginally more expensive than a standard plug. Still, they resist erosion better and require less voltage to generate a spark.
Of course, as they become worn out from the explosions and inevitable corrosion, spark plugs create weaker sparks over time. A worn spark plug reduces the efficiency of your engine and can eventually cause significant damage.
How do spark plugs work?
To get started, we need to begin with the basics - how does a petrol engine work?
Your petrol engine is a finely tuned machine designed to turn gasoline, your energy source, into movement. It does this through a process called internal combustion. In this process, valves fill your cylinder with an air-fuel ratio - this is a highly explosive combination. As the piston in your engine moves upwards, it compresses this mixture, creating even more potential energy from the gasoline. At an optimal level of compression, your engine ignites this mixture with a tiny spark, producing the power to move your car forward.
Where does the spark plug come into this? Your spark plug is what supplies the spark that ignites the air-fuel mixture, creating the explosion that allows your engine to produce power. It’s a vital component in making your vehicle move.
The spark plug creates an arc of electricity across two leads that don’t touch but are close enough that a spark can jump between them. Along with the electrical and timing equipment, your spark plug is a crucial part of your ignition system.
Manufacturers designed spark plugs to withstand a vast number of explosions. However, they may become “fouled” over time due to the explosions, the inevitable corrosion and other electrical or ignition system issues. As such, they lose their ability to spark the air-fuel mixture leading to smaller, weaker sparks and reducing the efficiency of your engine.
There are a few common symptoms you may notice if your spark plugs have gone bad:
- Rattling or knocking noises: When the plugs start to misfire, you may notice noise from the pistons and combustion engines not working correctly. If a spark plug fires at the wrong time, this could lead to the rattling or knock-like noises you hear.
- Hard starting: If your spark plug cannot create an adequate spark, your car may have trouble starting or feel jerky.
Engine misfires: Your engine may misfire if the spark plug wire or the spark plug’s tip that connects to the wire is damaged, causing an inadequate spark. - Reduced performance: When you’re driving, your spark plugs continue working even when accelerating and changing gears. If the spark is not functioning optimally, your vehicle’s performance will be negatively affected.
- Poor fuel efficiency: A quality spark plug helps to burn fuel efficiently in the combustion cycle, achieving optimal fuel economy for your vehicle. However, if your spark plugs are faulty, fuel may be wasted when your car fails to receive the proper spark at the appropriate time.
- Slow acceleration: When a spark plug becomes fouled, it doesn’t spark effectively, leaving your vehicle less responsive than usual, mainly when you try to accelerate.
Whether you notice signs of faulty spark plugs or when your vehicle is due for a service, chat with your friendly, local experts at JAX Tyres. We can inspect your vehicle and replace your spark plugs with high-quality spark plugs if necessary.
Luckily, spark plugs don’t require frequent replacements and can go years and many kilometres before needing a replacement. Most manufacturers these days will install “extended-life” spark plugs. They’re only slightly more expensive than a standard spark plug but are very resistant to erosion and require less voltage to generate a spark. The industry standard for these spark plugs is around 160,000 kilometres.
However, a spark plug’s lifespan depends on your specific engine, condition and the spark plug type. While “extended-life” spark plugs may run for 160,000 kilometres, standard copper spark plugs only have a lifespan of around 30,000 kilometres or two years. Some vehicles will also have shorter intervals, particularly performance and luxury models. For specific time frames and fuel filter types for your car’s make and model, you can consult your owner’s manual or contact your friendly, local JAX Tyres mechanic for expert advice.
The short answer? - it depends on how bad your spark plug is.
If your spark plug has completely blown out, your vehicle won’t start, let alone move. On the other hand, if the spark plug is slightly worn, you may still be able to drive your vehicle, but we don’t recommend it.
Malfunctioning spark plugs cause engine problems, including engine misfires, hard starts, reduced fuel economy, slow acceleration, and a general reduction in engine performance. As these plugs approach the end of their life, the gap between the two leads begins to widen, which leads to reduced efficiency and the possibility of misfiring. Driving with a faulty spark plug will be difficult because the engine might fail to function. Additionally, suppose your plug corrodes to the point where it breaks. In that case, it could seriously damage your engine cylinder’s interior, leading to a costly repair to get it fixed.
A bad spark plug often sounds like the engine is knocking at your door. When a spark plug fails to ignite all the gas and causes an inadequate explosion, the fuel and vapour will fire which causes a knocking noise. What’s more, if you have a bad spark plug, you may hear rough idling or vibrations instead of a smooth-sounding engine. Suppose you can hear rattling, knocking, rough idling or abnormal vibrations from your engine as you accelerate. In that case, it’s likely you have a damaged spark plug and should speak to a professional about repairing your spark plug.
The short answer is no.
Spark plugs are primarily known for their crucial purpose of creating an electrical spark across a small gap that ignites the air-fuel mixture within your engine. However, they are also constantly in use. As you drive, the spark plug continues to fire and ignite to keep your engine running. So, when you have a failing spark plug, you may notice a rough idle, sluggish acceleration or increased fuel consumption when driving.
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