Spark Plug Buyer's Guide
- A spark plug is one of the first few components that activate in your car the moment you interact with the ignition switch.
- Spark plugs ignite the gasoline and air being supplied in the combustion chambers.
- A spark plug is a small device typically made of high-nickel alloys, aluminum oxide ceramic, and steel wire as its main materials.
- Another function of the spark plug, which most people are not aware of, is that it acts as a heat exchanger.
- A typical spark plug has at least eight subparts: two electrodes, insulator tip, threads, gasket, shell, insulator, and terminal.
- There are four types of spark plug: copper, iridium, platinum, and double platinum.
- The most common cause of spark issue is a fouled spark plug because of grime deposits, which can happen if there’s always oil on the spark plug.
- Some consequences of running with a bad spark plug are poor fuel economy, lack of power especially during acceleration, difficulty starting, misfire, and bad idling behavior.
- A spark plug replacement cost from $4 (individual) while the most expensive one is a set of eight from GenuineXL, which is at $112.
A spark plug is one of the first few components that activate in your car the moment you interact with the ignition switch. Aside from that, it also works constantly for as long as your engine is running. Without the spark plug, it would be impossible for the engine to ignite the gasoline and air mixture.
Spark plugs are pretty straightforward. They ignite the gasoline and air being supplied in the combustion chambers. As simple as how they may appear, some people overlook the importance of a properly working spark plug. This buyer’s guide aims to teach everyone, car owner or not, the important things about these spark-generating devices—be it for replacement, upgrade, or troubleshooting.
What is a spark plug?
A spark plug is a small device typically made of high-nickel alloys, aluminum oxide ceramic, and steel wire as it’s main materials. It is considered as one of the smallest but most important components of a car. They mount right on top of the cylinder and are crucial for supplying your engine the spark it needs to ignite the fuel as it gets compressed. The spark plug does this by creating a tiny arc of electric charge between the two electrodes found on its tip.
Another function of the spark plug, which most people are not aware of, is that it acts as a heat exchanger. It does so by absorbing excessive thermal energy and passing it to the cooling system.
How does a spark plug work?
Before jumping right into how a spark plug works, you have to first know what parts comprise an assembly. A typical spark plug has at least eight subparts: two electrodes, insulator tip, threads, gasket, shell, insulator, and terminal. The assembly hooks up to a high-voltage power source, which is the ignition coil. The electric current coming from the coil causes a voltage difference between the center and side electrodes, leading to a spark. It may sound simple but it’s more complex in detail so let us break it down for you.
Before a spark is born in between the two electrodes, the gas between the gap needs to get ionized. For this to happen, the voltage needs to surpass the dielectric strength of the gas. This can only happen as the voltage rises. Ionized, the gas can now act as a conductor and allow the electrons to transfer from one electrode to the other, forming an arc across the gap. The gas then expands as the temperature in the spark channel rises and causes a small explosion.
Combustion happens when the small explosion caused by the expanding gases in the spark channel comes in contact with the compressed fuel and air mixture. A larger ball of fire takes place, which pushes the piston down so the process could start again. This keeps on happening thousands of times in one minute, which only shows how rigid and heat-resistant spark plugs should be.
Types of spark plugs
Nowadays, there are two common types of spark plug: iridium and platinum. However, there are four types if you include copper and double platinum. Here are the differences between them:
Copper Spark Plugs
Copper is an old spark plug material, although there is still quite a number on sale up to this day. This type features a core mostly made from copper, with nickel alloy as its central electrode. This small subcomponent is its weakness, as nickel alloy is not as durable as compared to other types of metal on this list—and so as copper.
Copper spark plugs do not last long. They work best when used in older vehicles as those old cars don’t need and have high electrical supply.
Platinum Spark Plugs
What most people don’t know is that platinum spark plugs also feature a copper core. The only difference is that copper spark plugs have nickel alloy tips instead of a platinum disc found on platinum spark plugs. Platinum is harder than nickel alloy with a melting point of up to 3,215 degrees Fahrenheit (compared to 2,647 degrees for nickel alloy).
If your car features an electronic distributor-based or distributorless ignition system (DIS), it’s highly recommended that you use a platinum spark plug.
Double-Platinum Spark Plugs
A double platinum spark plug has an additional platinum disc on the underside of the side electrode. This reinforces the side electrode just like how the platinum cap does to the copper core. Double-platinum spark plugs allow the spark to jump back from the side electrode to the central electrode. The platinum on the side electrode enables it to handle reverse spark. The return of spark is crucial if you have a “waste spark” DIS.
If your car is using a double-platinum spark plug by default, don’t try to downgrade to a single platinum plug. Single platinum plugs lack a side electrode that can handle a reverse spark.
Iridium Spark Plugs
Iridium is the hardest metal of all three, meaning it can last longer than both copper and platinum types. Iridium spark plugs feature a fine iridium tip welded onto the fine wire electrode core. They are some of the best spark plugs in the market. There’s also a variety with a platinum disc welded on the side electrode for coil-on-plug (COP) system compatibility.
Given the size of the iridium material, this spark plug doesn’t require huge voltage to generate a spark. This means that they are more efficient than other types. The only downside is that iridium is an expensive metal. Even after reducing the electrode size to as little as 0.4 mm, the iridium spark plug is still the most expensive of all types.
What causes a bad spark plug?
Spark plugs can fail because of several reasons. The most common of all is a fouled spark plug caused by grime deposits, which can happen if there’s always oil on the spark plug. When spark plugs fail, you will experience multiple performance and comfort issues with your car.
Consequences of running with a bad spark plug are poor fuel economy, lack of power especially during acceleration, difficulty starting, misfire, and bad idling behavior. If you notice one or two of these symptoms, have your car checked by a certified mechanic as soon as possible.
Choosing the Right Spark Plug
A lot of people think that a spark plug problem is easy to solve. You just have to replace the worn-out part with a new one and that's pretty much it. Or is it? Contrary to what some people believe in, we'd like to think that there's more to it than simply changing the faulty spark plug with the first aftermarket component that you will see online. You see, more than anything, this vehicle maintenance is all about making decisions-the right decisions, mind you. About what, you ask? Well, one crucial decision you have to make-which is also the most difficult one-is what kind of spark plug to get for your car.
What to look for in your spark plug?
Durability dictates the lifespan of your spark plug. If it's not made to withstand the wear and tear that comes with its function, rest assured that you won't get your money's worth-it is that simple.
Fit simply allows you an easy installation process. As long as you acquired a spark plug that matches your vehicle's specific make and model, you can guarantee that installing it won't be that complicated.
Copper vs Platinum vs Iridium
Which of these three is the best material for your spark plug? That's the question you have to answer. Here's a list of pros and cons of every material:
- Melting point: 1, 983 degrees F
- Lifespan: 15, 000 - 20, 000 miles
Melting point: 3, 222 degrees F
Lifespan: 30, 000 - 60, 000 miles
- Melting point: 4, 229 degrees F
- Lifespan: 60, 000 - 100, 000 miles
In the end, you have to decide what's best for your car. If you want a spark plug that's really good in conducting electricity, go for a copper-made one. If you want a spark plug that would last long, you should get a Platinum- or Iridium-made spark plug. But then again, it is not that simple. There are also other factors that would come into play once the spark plug is installed inside your engine. However, if you make the right choice, rest assured that it can help maximize the performance of your vehicle.
How much are spark plugs?
OE spark plug replacements on CarParts.com are some of the cheapest but most reliable ones in the market. A spark plug replacement cost from $4 (individual) while the most expensive one is a set of eight from GenuineXL, which is at $112. You can enhance your search experience by indicating your vehicle’s year, make, and model in the filter tab. This will filter the results with all the compatible units for your vehicle.
What to Do When your Spark Plugs Fail
There are only a few things in this world that can surely ruin your morning and eventually, your whole day. You may run out of hot water while you're in the middle of a shower, have a very unsatisfying breakfast, and-take our word for it because WE KNOW-faulty spark plugs in your vehicle. Now, since this page is all about cars, we're going to teach you how to fix the last problem on your own. There's also no need to worry if you've got zero experience in automotive DIY because this is one of easiest car part replacements that you will ever encounter. Just carefully follow the instructions below and you'll be alright.
Difficulty Level: Easy
Tools that you'll need:
- Ratchet wrench
- Spark plug socket
- 12-inch socket extension
Step 1: Assuming that you already know where the spark plugs in your ride is located (if you don't, just follow the thick, rubber-covered wires under the hood), you can start by removing the wire from the first spark plug that you'll replace. No tools needed to do this. Just wiggle it to make it loose.
*Note: Be extra careful not to pull the wire out of its boot. You might have to get a new one if that happens. The boot comes in a set too, making that mistake a costly one both literally and figuratively.
Step 2: Put the extension and spark plug socket on your ratchet. Use this to loosen the spark plug (counter-clockwise) and remove it from the engine.
*Note: Examine your old plug. If it is oily or has a crack on the porcelain insulator, it indicates other problems that you need to take care of.
Step 3: Put the new spark plug in the socket and place it by hand. You can finish tightening it by using a wrench. After this, you can put the wire back on the spark plug.
Warning: Even if this goes without saying, we still feel the need to warn you about this. You see, IT. IS. NEVER. SAFE. to do a repair under the hood when the engine is still hot. Let it cool down first.