Have you ever decided to give your car a tune up yourself only to find that the spark plug installation is confusing? Spark plugs have to be installed in a certain order for your car to run properly. If you are not sure how to change your spark plugs, read on to find out how.
Do You Need Spark Plugs?
The internal combustion system runs with the help of spark plug firings. Spark plugs are some of the smallest components in your vehicle’s system. Yet, the necessity of spark plugs is perhaps larger than most other components in your vehicle’s system. The first internal combustion engine that used a spark plug was Etienne Lenoir’s gas engine. Lenoir used electric spark plugs. Accounts of who made the first spark plug credit Lenoir while others credit Edmond Berger with the first spark plug made in 1839. An electrical current flows from the ignition coil which generates a voltage between the side and central electrodes.
What is a Spark Plug?
The internal combustion engine is comprised of many components that must together to start the engine and keep it running. Spark plugs play a critical role in the igniting of the gases in the internal combustion engine. They usually require between 12,000 and 25,000 volts of electricity to fire up. However, some plugs can ignite with as much as 45,000 volts.
A spark plug is a small component with a shell, central conductor, terminal, and an insulator. Electrical discharges occur in the space and initiate combustion of the air/fuel mixture.
The body of spark plug is made of a hard, ceramic material that has a high dielectric strength, preferable heat conduction, and resistance to heat shock. The ceramic is glazed to improve resistance. The terminal is located on top of the plug and connects it to the ignition. Many models have spark plug wires that snap into the terminal of the spark plug. Cup-style terminals allow for longer ceramic insulators in the same space. The insulator may be smooth or ribbed and provides stability to the center electrode inside the plug. The top of the insulator extends the spark plug above the cylinder head so that it is more accessible. The bottom of the insulator extends into the combustion chamber. The insulator is usually made of aluminum oxide. Different gasoline engines require different sized spark plugs. The size of the plugs differs by size, quality, and by country.
What Do Spark Plugs Do?
Spark plugs provide a gap inside the combustion chamber in internal combustion engines. The plugs are designed to produce a timed spark which is used to ignite the combustion material. The high voltage used to ignite the plug comes from the ignition coil or the magneto. The ignition coil is electronic, located in the ignition systems, and converts the voltage to a spark that can ignite the combustion material. The computer in the vehicle controls when the spark plugs will ignite. The voltage eventually exceeds the dielectric strength of the gas and the gases become iodized. The spark channel becomes so hot that it causes the iodized gas to expand. The end of the spark event is characterized by a small fire inside the spark gap. The spark is enough to make the engine run.
Spark Plug Firing OrderChanging the spark plugs can become complicated when you’re not sure of the order. In order for the engine to start, the plugs must be wired correctly. The main things that you must know about wiring the plugs correctly are the firing order, the cylinder ordering, and the direction of the distributor rotation. Once you are familiar with these things, changing the spark plugs is pretty easy. In order to install the spark plugs correctly, follow these steps:
- Check the repair models for the right type of spark plugs for your car’s make and model. You may check local automotive stores or the Internet. The replacement spark plugs do not have to be the same brand as the plugs you are replacing. As long as the plugs are the correct size and have the right heat range, you can use them.
- Park the car in a safe place and pull the parking brake on.
- Find out in which direction your distributor rotor rotates. The rotor is usually under the distributor cap. The distributer rotation can be clockwise or counterclockwise. Remove the distributor cap and turn on the engine. Watch the rotor to see what direction it is spinning in.
- Check the repair manual to find out where the distributer number one firing terminal is. You can also find the number one firing terminal by manually turning the engine until you line up the crankshaft and the camshaft timing marks.
- Find the number one cylinder on the engine block. The numbers and orientation of the cylinders is different between vehicle models. You may need to check the manual to find it.
- Connect a spark plug wire between the distributor number one terminal and the number one cylinder.
- Based on the direction of the rotor movement, connect the rest of the spark plug wires. Connect the wires one at a time using the firing order in the repair manual. The firing order begins at the distributor number one terminal and continues in the right direction until it reaches the distributor number one terminal again. The firing order for 1,3,2,4 is clockwise and cylinder three should be connected to the distributor terminal which is immediately clockwise from the distributor number one terminal. Connect the second cylinder to the distributor terminal which is immediately clockwise from the distributor number three terminal. Connect the fourth cylinder to the distributor terminal which is immediately clockwise from the distributor number two terminal.
- Compare the wires to the instructions in the repair manual to make sure they are connected properly.
Engine Still Won’t Perform
If you are confident that the spark plugs are installed correctly and your car is still misfiring, it could another problem related to the spark plugs. This is often the case with the ignition coil. There is a test that you can perform to test the ignition coil. To test the coil, follow these steps:
- You should get someone to help you perform this test.
- Park your car in a safe place and turn the engine off.
- Pull the parking brake on and let the car cool off completely.
- Lift the hood and find the ignition coil. If you are not sure where the coil is located, check the repair manual, call an auto repair shop, or do an Internet search.
- Remove one wire from a spark plug. Use a spark plug socket to remove the spark plug.
- Attach the spark plug wire that you removed back on to the spark plug.
- Touch any metal part on your car with the threaded part of the plug.
- Remove the fuel pump relay. Again, refer to the repair manual to locate the relay.
- Have someone turn the key in the ignition while you look under the hood.
- If you see a blue spark between the spark plug thread and the metal when the car is started, the ignition coil is working, and you need to check the spark plugs. If there is no reaction from the contact with the metal, the ignition is probably not working
What happens When Spark Plugs Are Not Installed Properly
How do you know when it’s time to change the spark plugs? Spark plugs should be replaced every 20,000 to 40,000 miles. This can vary depending on the make and model and how often you drive the car. High performance vehicles require spark plug changes more often.
Spark plugs cost between $15 and $100. You may pay up to $150 additional for labor if you go to the car garage to get them replaced. When the spark plugs are installed properly and working as they should, most plugs last for the factory service interval of 100,000 miles. Some may last even longer. Long-life iridium and platinum spark plugs normally last for the 100,000 miles. However, if spark plugs have been in the car for a long time and the vehicle isn’t being serviced, the spark plugs become corroded before 100,000 miles. This is especially true when the spark plugs are uncoated. If you purchase a used vehicle, you should immediately check to see when was the last time they were replaced.
When the spark plugs do not fire in the sequence, there are several firings going on, out of order, and simultaneously. That means the combustion material is not being lit in the proper sequence. These problems will surely exhibit symptoms of a problem. Here are the most common signs that the spark plugs need to be changed or ordered properly:
Misfiring– Spark plugs are supposed to ignite the air/fuel mixture inside the combustion chamber. When the spark plugs are not ordered properly, the air/fuel mixture cannot light up in a consistent pattern. This causes the engine to misfire. When driving at high speeds, you may probably feel the engine hesitate for a few seconds and then resume. One spark plug that is not in the right order can cause these problems. However, this can also happen when the spark plugs are dirty. When the spark plugs are dirty or damaged, the air/fuel mixture is not regularly lit. This causes your engine to sputter and misfire.
Lack of acceleration – If the spark plugs are not properly ordered, you may find it hard to accelerate. The engine and plugs are already out of sync, which causes misfiring. In more serious cases, the car will struggle to accelerate. In some cases, the engine will not start at all or will cut off unexpectedly.
Higher gas consumption – When the spark plugs fire irregularly, the engine could consume more gas. The irregular firing causes the engine to misfire which cause a higher consumption of fuel for the engine to continuously run. The bad plugs can also cause an increase in emissions.
Uneven vibrations – When the spark plugs need changing or are not installed properly, the engine will run at a lower RPM when idling. The engine will idle progressively rougher until other problems arise.
How to Fix Bad Spark Plugs
If your spark plugs aren’t functioning properly, it means that the combustion process in the engine is going to be affected. Making sure that the spark plugs are maintained will stop them from going bad and it’ll allow the combustion process to start working properly again. If the spark plugs are bad, this can affect the engine negatively and this can cause it to blow in the long term. The last thing you want to experience is a blown engine because the cost to fix it is very expensive.
If you want to avoid spark plug problems or other issues and save $100s of dollars that you’ll spend at the auto repair shop, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.
A lot of our readers have the Auto Maintenance and Repair Manual printed on their garage wall and 92% of them haven’t visited the auto repair shop in the last year because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the workshop again.
Go to a Repair Shop
Until you buy an electric car, you will always have to have spark plugs. If you have not been able to successfully install the spark plug wires and the ignition coil test failed to show any problem with the coil, take your car to a repair shop and have then replace the plugs. Driving with spark plugs that are not installed correctly is dangerous. Get the spark plugs installed properly and drive safe.