If you’re familiar with cars, you’ll know that spark plugs are those things that ignite your fuel and start your car. They don’t last forever, and you’ll need to replace them at some point. Can you grab any pair of spark plugs in your workshop, and are spark plugs universal? Let’s find out!
Sparkplugs are not universal, differing by length, diameter, temperature range, gap, and material. Connecting the right spark plug to your engine is vital, or you may experience overheating, poor ignition & engine performance, piston damage, more gas emissions, and thousands of dollars in damage.
You don’t need to be an automotive mechanic to understand spark plugs, but there are some essential things to consider. Let’s discuss why you must match the right ones with your engine and the consequences if you neglect them. We’ll also look at how to know what type of spark plugs you need and whether operating your vehicle with a missing spark plug is possible.
Spark plugs are not universal and come in various lengths, sizes, temperatures, and gaps, making it essential to match them to the right engine. It’s similar to how Ford cars get an AdvanceTrac warning light due to mismatched parts.
Diameter & Length
Spark plugs have different diameters that screw into the cylinder head, like 10m mm, 14 mm, and 18 mm. If the spark plug is too small, it will cause a loss of compression, and gases may leak out and cause ignition problems. If the spark plug is too large, there’s a good chance the threads will become damaged, or the cylinder head will crack and deteriorate.
When we talk about the length of a spark plug, it refers to the position of the gap relative to the fuel and piston. Spark plugs that are too long will interfere with the valve and pistons and cause a lot of damage to your engine. If they are too short, you’ll have trouble starting your car because the spark won’t reach the fuel.
Temperature, Gap, & Material
Different spark plugs run at different temperatures, affecting their ability to resist fouling and pre-ignition. Fouling can be a significant issue because the gunk will prevent the tip from receiving adequate voltage, and your car will experience problems with its ignition, acceleration, and even gas mileage.
Reduced acceleration can be dangerous when you need to overtake in an emergency or get out of a blind spot. You wouldn’t compromise on your brakes, ensuring quality brakes like Duralast, so ensure your family’s safety and peace of mind by getting the right components.
Spark plugs that run hotter have longer insulators but smaller surface areas to retain more heat. Colder sparkplugs have a larger surface area so that they can transfer more heat, but the heat also dissipates quickly.
If it’s too hot, it may cause pre-ignition or detonation, which can melt or erode the electrodes or pistons. Cold temperatures are more susceptible to fouling and misfiring and have a weaker power output with more emissions.
A spark plug gap is the distance between the center and ground electrodes at its tip. It affects the spark plug’s ability to generate a strong and consistent spark, and if it doesn’t match your engine’s specifications, it will result in poor performance.
A gap that is too wide will require the voltage to jump a greater distance, meaning the spark will be weaker or erratic. A narrow gap will reduce the duration or intensity of the spark.
The vital part of the material refers to the electrodes at the tip of the spark plug and affects its conductivity and durability. The most common types are platinum, silver, iridium, copper/nickel, and double platinum. They each have unique characteristics that must work in conjunction with your car’s engine:
- Platinum electrodes have lower melting points than iridium electrodes but higher corrosive resistance.
- Silver electrodes have impressive conductivity but low resistance. They are rare and expensive.
- Iridium electrodes are less conductive but have superior durability because they require less voltage to spark. They are slightly more expensive, too.
- Copper/nickel electrodes have good conductivity but have a short lifespan because they require a strong voltage to generate a spark. They are cheap compared to other materials.
- Double platinum electrodes have improved durability and performance because they have platinum on both center and ground electrodes.
What Happens If Your Spark Plugs Don’t Match Your Engine?
You will likely damage your pistons if you use a spark plug that is too long or doesn’t run at the correct temperature. If it goes on for a while, you’ll eventually have to remove and replace it, which can cost a pretty penny!
It’s also possible for the spark plug to become damaged if the heat range is too high, even causing it to melt. The truth is that spark plugs aren’t expensive, so it’s worth taking the time and buying the ones you need.
It’s wise to add some anti-seize compound on the threads so they can perform better for longer and avoid making them too tight. The worst that could happen is they wiggle out, and you tighten them again.
How Do You Know What Spark Plugs You Need?
The most straightforward method for knowing how many sparkplugs you need is by checking your owner’s manual.
If your owner’s manual insists on copper spark plugs, avoid taking shortcuts and downgrading to copper or going for cheaper options because you want to save money. Get the right match for your engine to avoid damaging it and potentially paying thousands of dollars in repairs.
If, for whatever reason, you don’t have one, do a quick online search for your car’s manual via the manufacturer’s website. This method comes in the form of a compatibility tool, which allows you to enter your vehicle details and display the matching spark plugs for your engine. Sometimes, they even suggest possible upgrades that guarantee better durability and performance.
Here’s what the compatibility tools look like for Bosch, Denso, and NGK.
Another way is to decode the part and stock numbers on your existing spark plugs. These numbers indicate the spark plugs’ size, length, temperature, gap, and material. They help find the equivalent spark plugs across different brands, especially if you want to swap your current spark plugs for different ones.
If you prefer the hands-on approach, lift the hood and examine the number of wires leading to sparkplugs. Using your finger, count how many there are; if you have a twin-plug engine, you may also need to use your toes!
Will Your Car Work With A Missing Spark Plug?
Your car can work with a missing spark plug, but it should only be a temporary solution. It will have a reduced performance; the longer you leave it, the greater the chance it will become damaged beyond repair.
It may not be as noticeable with an eight-cylinder engine, but you may feel a physical difference with a four-cylinder engine.
It should never be a go-to solution because allowing unfiltered air through the hole will give way to dirt, gunk, and other things that don’t belong. For instance, a little rust that makes its way from the exhaust manifold will severely scratch the interior of the cylinder wall.
Do All Modern Cars Use Spark Plugs?
If your car has a gasoline engine, then it will use spark plugs. When you want to start your vehicle, the spark plugs will make it happen by igniting the gasoline with a spark.
If your car has a diesel engine, you won’t have spark plugs. Diesel engines use compression to ignite the car’s fuel. Despite running on electricity, electric-powered vehicles won’t have sparkplugs because they don’t rely on gasoline or don’t need to burn anything flammable.