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What Do Spark Plugs Do? (+8 FAQs)

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Spark plugs are tiny but critical engine components responsible for a very important job.

But what does a spark plug do? 
And what do they contain? 

In this article, we’ll look at how spark plugs work. 
We’ll also cover the various types, how to choose one, how frequently to replace them, and more. 

This Article Contains: 

Let’s begin!

What Do Spark Plugs Do?

Spark plugs are typically housed on the cylinder head of the engine. They create a tiny high-voltage spark through the ignition coil in the internal combustion engine. 

Think of it as a tiny electrical spark required to start the car

But how do they do that? 
Your engine works by converting an energy source (like gasoline) into a power source to run the internal combustion engine. 

It starts with your valves filling up your cylinder with an air fuel mixture. The piston then moves upwards and compresses this air fuel mixture, creating potential energy. This is where the ignition wires come into action.

Your car’s spark plugs create an ignition with the help of a small high-voltage spark. This then moves the piston downwards, turning the crankshaft, and getting your engine in motion

In other words, your car can’t start without the spark plug. Their condition also affects your car’s engine performance, fuel economy, and every function.

Keeping this in mind, let’s take a look at the different types you can get for your car. 

What are the Different Types of Spark Plugs?

A range of materials can be used to manufacture a spark plug, each with its own set of benefits and characteristics. 

Here are the different types of vehicles spark plugs you’ll typically encounter in the market: 

A. Copper Spark Plug

Copper spark plugs were the industry standard before the others came along. They’re affordable and commonly available. They feature a copper and nickel core. However, a copper spark plug usually has a very short lifespan. 

B. Platinum Spark Plug

Unlike copper spark plugs, a platinum spark plug consists of a platinum center electrode which adds longevity to its shelf life. It will also perform in a wider temperature range and generate more heat in the internal combustion engine.  As a result, a platinum spark plug is less vulnerable to carbon build-ups. 

C. Double Platinum Spark Plug

While a single platinum spark plug will feature a platinum center electrode, a double platinum spark plug also contains a platinum ground electrode! These do tend to be pricier but offer far better longevity and performance. 

D. Iridium Spark Plug

Iridium spark plugs have a ‘fine wire’ center that conducts electricity and a small ground electrode that lowers the voltage required for ignition. Iridium spark plugs are used for high-performance engines.

E. Ruthenium Spark Plug

Ruthenium is one of the new metals used in spark plugs. It offers high ignitability, helping enable complete combustion and cleaner exhaust gases. They are supposedly more durable than iridium spark plugs but cost more.

F. Silver Spark Plugs

Silver plugs are quite rare compared to iridium spark plugs or double platinum spark plugs. These contain a silver-plated ground electrode with better thermal stability but lower longevity. 

With so many options, how do you choose a new spark plug for your car? 
Let’s find out the answer to that and other queries. 

8 Spark Plugs FAQs 

Here are some frequently asked queries about spark plugs and their answers. 

1. Which Spark Plugs are Best for My Car?

One way to find the best fit when changing spark plugs is to stick to the same brand. When buying a new spark plug, ensure that you get the same brand and model as your old spark plug. 

You’ll probably never have to worry about upgrading your old spark plug unless you modify your engine. In this case, you should refer to your vehicle manual for advice. 

It also depends on your car’s age and type. 
Older engines usually use copper plugs, whereas newer, high-performance engines may require double platinum spark plugs. 

You can also choose between a conventional spark plug or premium spark plug, according to your preference. 

Remember, if you have doubts regarding buying a new spark plug or the spark plug type you need, always reach out to your mechanic for the best fit for your car!

2. Do Diesel Engines Have Spark Plugs? 

Diesel engines do not have conventional spark plugs (like gasoline engines), as it relies on a compression ignition and glow plug. Here, the glow plug is used to heat the combustion chamber. This aids the ignition system if the diesel engine gets cold. 

As compared to spark plugs, a glow plug is only required during the ignition process. It is an electrical device that heats the cylinder head in each combustion engine. So you never have to worry about changing spark plugs when it comes to a diesel engine!

3. What are the Signs of a Failing Spark Plug?

Indicators of failing or faulty spark plugs include:

If your car displays any of these warning signs, it’s best to have your vehicle checked by an auto repair professional. 

4. What Causes Spark Plugs to go Bad?

There are various reasons spark plugs could go bad, including:

5. Why Do I Need to Change My Spark Plugs? 

As your spark plug gets old, it faces engine wear and deteriorates in quality and efficiency. 

But when a bad spark plug is replaced, you’ll notice benefits like:

6. How Frequently Should I Change My Car’s Spark Plugs? 

Spark plugs do not require a replacement very often unless you have a faulty spark plug. In fact, “extended-life” premium plugs can go about 100,000 miles without needing any repair. 

These are typically a lot more expensive than a conventional spark plug. However, they last a lot longer with minimum maintenance.

Most manufacturers and car mechanics recommend changing them every 30,000 miles. This applies to all standard and premium types. However, the mileage may fluctuate depending on the brand and model.

Note: If you experience a misfire or incomplete combustion within the combustion engine, check the spark plug gap. Worn spark plugs can increase the spark gap and trigger an engine misfire and the check engine light.

7. What Parts Make Up a Spark Plug?

A spark plug comprises:

8. What Are Cold vs Hot Spark Plugs? 

This refers to the heat range. It is determined by the insulator nose length. A longer insulator nose will force more air through the spark plug wire to the tip. 

Hot plugs can insulate better, retaining more heat for the tip. 

Cold spark plugs conduct more heat through the ignition wires and ignition coil and cool down the plugs. 

Closing Thoughts

A faulty spark plug can drastically affect your car’s engine performance and fuel efficiency, among other things. You may also face excessive noise and an engine misfire. 

If you have a fouled spark plug, your mechanic can disconnect the spark plugs, inspect them, and fit them back in or perform a replacement. They’ll also ensure that the gap is within the recommended range and everything is properly connected. 

For an affordable and reliable spark plug replacement service, why not contact RepairSmith?

RepairSmith is a mobile auto repair and maintenance service that offers a range of services, including replacing spark plugs and your routine oil change. Plus, you get a 12-month | 12,000-mile warranty on all repairs! 

Fill out this form for a spark plug replacement cost estimate. 
You won’t have to worry about them failing ever again!