Spark plugs are one of the few things that require little or no maintenance for most car owners, and this is probably not without good reason. But, unfortunately, many people are unaware of what goes on inside a spark plug and how it affects their vehicle’s performance.
So let’s dive deeper into the details on how spark plugs work to understand why they need changing and when.
How to tell if you need new spark plugs
Below is a shortlist that could indicate it’s time for new plugs. If you’re experiencing any of these, take your car for a checkup to determine what’s needed. Driving around with the listed issues can eventually cause more damage and, even worse, more expensive repairs.
- A rough idle at a low RPM.
- White smoke on acceleration or deceleration. This appears when the engine is running rich and could result in a costly problem to repair. Your car might be burning oil if you see white smoke in your exhaust.
- If you see black smoke on acceleration or deceleration, it could mean that your engine is running too lean (not enough fuel), which means that the spark plugs might not be able to ignite all of the air and fuel mixture.
- Your car stalls or won’t startup. It could indicate that there is not enough spark at certain times.
- Your engine runs hot. This could be caused by poor combustion in the combustion chamber, so it’s essential to check all of your other engine components for problems as well. Low coolant can also cause damage to other engine components.
- If you have poor gas mileage and drive an automatic transmission car, it could indicate that there is not enough spark to keep the engine in its power band while going. This will cause you to have to downshift to accelerate.
Why is my spark plug black?
It is usual for nearly all spark plugs to have a lot of black soot on them. However, you should note if the insulator has actually turned black or is just covered in oil. Also, your spark plug should not be black if you change it regularly and/or use the correct heat range (the wrong heat range will burn off excess deposits).
You can clean the old plugs with a wire brush or install new ones. Ensure that the insulator inside is clean before installing it (look through the ceramic holes to be sure); otherwise, you will have other problems.
Can you clean the plugs and re-use them?
I’ve used a wire brush and brake cleaner in the past to clean plugs for my motorcycle, which worked well. However, I found this video on YouTube showing another method used to clean spark plugs, which works well.
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How many spark plugs are needed for an engine?
Plug types depend on the vehicle you drive. You may also consider going with a more expensive type if you often have a problem with your vehicle misfiring.
Below is a list of the different engines and the number of spark plugs for each.
4-Cylinder engine:
There are 3 spark plugs if the engine is a V-Type, or 4 spark plugs if the motor is inline.
V6 Motor
A 6-Cylinder engine will have 2 for each cylinder bank (cylinders on opposite sides of the crankshaft). Therefore, the first two cylinders in a six-cylinder engine would have 1 spark plug each, the next 2 would have 2 spark plugs each, and the last two cylinders will have 3 spark plugs each.
There are also V-Type 6-Cylinder engines with one ignition coil per cylinder bank (so there is still 1 ignition coil per 4 cylinders).
7-Cylinder Engine
A 7-Cylinder engine has a total of 6 spark plugs.
8-Cylinder Engines
An 8-cylinder engine will have 3 for each cylinder bank (just like in a 6-cylinder).
10-Cylinder Engines
And finally, a 10-cylinder engine has 5 for each cylinder bank.
There are also V-type 10-Cylinder Engines that have 2 ignition coils per cylinder bank. This type of engine usually has two plug wires for each spark plug.
Should you hire a service center to change the plugs?
It’s not necessary to hire a mechanic. However, be cautious if you want to do it yourself, be sure the engine is cooled off before starting.
The procedure is not complicated, but it requires patience and time to complete correctly: You will need a selection of sockets in various sizes. All sockets should be the same size or close to it. You’ll probably need an extension bar and a ratchet handle (preferably digital). Lubricate your sockets with an anti-seize compound, so they slide in easily. In addition, you will need new plugs with the correct heat range for your vehicle.
A good time to change spark plugs is while performing an oil change on your vehicle. When changing oil and spark plugs, use synthetic oil if possible (it lasts longer and is better for the engine).
Steps to change the plugs
Change the spark plugs yourself using the steps below.
- Remove each spark plug wire one at a time (Don’t mix them up)
- Clean around the spark plug opening so no dirt, oil, or gunk can get down into the cylinder when you remove each head.
- Loosen the spark plugs using a wrench made explicitly for removing them (called a “reach plug wrench”).
- Remove the top section and clean by spraying a penetrating oil down into the threads, then twisting clockwise to loosen. Make sure you spray in between the ceramic insulator and ground electrode. Otherwise, it will be difficult to remove.
- Next, place each spark plug down into the holes and tighten them to the specs listed in the owner manual.
- Place each wire back on. While doing this, make sure you don’t mix up each wire.
How long does it take to replace spark plugs?
On average, around an hour per spark plug – depending on where they are located.
Should I replace the spark plug wires?
It’s best to change them simultaneously as your spark plugs, but they are suitable for the vehicle’s life in most cases. New wires will typically cost more than spark plugs. It is recommended that you check the cables for cracks and change them if they are cracked or have gunk around the end.
How much do spark plugs cost?
For most vehicles, the plugs are typically less than $10 for a set of 4. However, some kits include an oil filter with new spark plugs that cost around $20 – $25.
You can buy spark plugs cheaper online or at some auto parts store, but you’ll need to determine if they are the correct heat rating for your vehicle.
Which should you buy?
Most vehicles have “platinum-tipped” spark plugs, which last longer than regular ones (typical life span is between 50,000 – 100,000 miles). Some cars have platinum-titanium plugs (such as some Nissan Altima’s), which should last around 150,000 to 200,000 miles.
You can also use ceramic spark plugs, but they don’t last as long and tend to fail internally, so they are not great for high mileage vehicles.
When you buy your spark plugs, make sure they have the “recommended by vehicle manufacturer” somewhere on the box to ensure that they work correctly in your car. Even if you buy them at an auto parts store, ask someone there to check which ones are correct for your vehicle and see if using them is ok. I always buy the NGK’s for the best quality.
What is a spark plug?
A spark plug is an electromagnetic device that fits in the engine’s cylinder head and ignites the fuel/air mixture in a controlled manner. The main job of a spark plug is to provide high voltage (12,000 volts or more) to help create a small explosion inside the combustion chamber of a car’s engine. This explosion is responsible for providing the energy needed to power an automobile.
The job requirements set by spark plugs are more demanding than those required in other applications, such as lighting, air conditioning, and heating systems. This is because the high voltage produced in the combustion chamber can be much higher than 12-volt lights, for example, and it has to be built in a controlled manner. But, on the other hand, the high voltage also carries pulses of current that can be extremely short, making the requirements even more demanding.
The spark plug part that provides the high voltage and most electricity to the combustion chamber is called a center electrode. This electrode is made of a material that conducts electricity (usually nickel-chromium), and it is located in the middle of the spark plug.
This electrode’s area is called an insulator because it does not conduct electricity like the center electrode. The insulator is made of ceramic and is designed to withstand high temperatures that can reach 5,000 degrees Fahrenheit. However, the insulator is not 100% solid, so it has a couple of small holes that allow a small amount of electricity to reach the center electrode when needed.
There are 2 other electrodes on the spark plug: the side electrode and the ground electrode. The purpose of these electrodes is to add more energy to the combustion chamber, so they are also made of a material that conducts electricity.
The spark plugs on your car have built-in resistors (materials that block electricity) that actually limit the flow of electricity through the side and ground electrodes to prevent electrical damage from occurring to other parts of your engine.
The ground electrode is located in an area called a counter-electrode. Its job is to prevent electrical damage when working on top of the engine. It provides a path that discharges electricity away from the engine.
The side electrode is located closer to the center electrode, and its purpose is to improve efficiency. It also improves fuel efficiency, so most modern cars use a design where the entire circumference of the spark plug has this kind of material on it rather than just having it in a small ring around the outside edge of the electrode.
Different spark plugs are used for various driving conditions. For example, performance-tuned spark plugs produce a hotter and more concentrated explosion inside the combustion chamber than other types of spark plugs. These usually have a long ground electrode and a side electrode that is angled to provide an even better performance in your vehicle.
There are also spark plugs that produce a better explosion inside the combustion chamber. This kind of plug is designed for vehicles that can drive longer distances, so it has a side electrode that produces a broader and more diluted spray of fuel/air mixture into the combustion chamber (which helps cool the engine down while driving).
Conclusion
I hope you found this article helpful, both on how to change spark plugs for a vehicle you own or someone else’s. Also, check out our other automotive articles and let us know if there’s an article you would like to see on Auto Glass Locator in the future.
