How To Test Spark Plug Wires – What You Need To Know!

When looking at how to test spark plug wires, there are certain indications that can clue you into faulty spark plugs. These noticeable signs and symptoms can alert the driver to issues with the sparkplugs, causing performance reductions and problems with the engine and transmission in your vehicle. 

 

In addition, learning how to test spark plug wires involves analyzing and using one of the three main methods to test for problems. These three methods include testing the spark plug wires with the engine on, testing with a meter or diagram, and testing the spark plug wires with the engine off. 

Signs That Can Indicate Faulty Spark Plugs

 

As we know by now, spark plugs are a key part of the engine and the function of the engine in your car. By keeping your engine and spark plugs healthy, you can ensure that the ignition timing produces the right amount of energy to fuel the car. If the ignition timing is off, the engine will not be able to run and use the fuel and air mixture to move the vehicle. If the timing is off, it is time for you to learn how to test spark plug wires. 

 

Keep in mind – spark plugs are not meant to last forever. In some cases, the spark plugs in your vehicle might even fail before the intended lifespan, meaning that you have to look into the spark plug replacement and keep an eye out for the signs of what a spark plug misfire feels like. Keeping an eye out for the faulty spark plug signs indicate you need to learn how to test spark plug wires. 

 

Typically, spark plugs need to be replaced every 30k miles, usually included in most routine maintenance at local mechanic shops and for your specific vehicle. To prevent a more expensive replacement, you need to know the signs of faulty spark plugs in your car that can influence you to learn how to test spark plug wires. 

 

• Engine Misfiring

 

An engine misfire usually occurs for only a split second in your car and then will regain operating at a normal performance level. However, this can significantly hurt your engine if you do not fix the engine misfire’s problem. Failing spark plugs can cause the car engine to misfire, reducing your horsepower, acceleration, and control of your vehicle. Make sure when you notice the signs of engine misfiring that you learn how to test spark plug wires. 

 

Just one singular spark plug that is faulty or damaged can cause your entire engine to misfire, resulting in a lack of performance and safety. If the air and fuel mixture begins to develop an improper ratio, this can result in the engine running poorly. If the engine does not combust at the right time, the caf will not run, and the catalytic converter will be damaged during use. 

 

• Trouble Starting the Car

 

Faulty spark plugs can cause your car to have issues with starting at the right time or starting after a long period of time being off. Damaged spark plugs will not produce the necessary power of sparks or the correct timing of sparks, which is required to start the engine and keep it running while driving. This starting trouble results in the engine stalling, which is dangerous while driving.

 

In addition, failing spark plugs or damaged plugs can cause the battery to drain much quicker than usual, meaning your car’s electrical components will not work correctly. If you notice your car is not starting when you turn the key in the ignition and the battery is draining quicker than usual, you might have to learn how to test spark plug wires. 

 

• Increased Fuel Consumption

 

If your fuel is decreasing much quicker than usual and you realize that the fuel efficiency is significantly declined, this is a sign of damaged spark plugs. Normal spark plugs will produce the necessary spark to ignite the fuel and air mixture at the proper ratio within the internal combustion engine. However, if the ratio is not correct or the fuel consumption is too high, the ignition will leave behind residue and contaminated emissions.

 

Malfunctioning spark plugs can increase emissions, leading to the emission test’s potential failure and increased fuel consumption due to the internal combustion process not being completed on time, leading you to learn how to test spark plug wires. 

 

• Lack of Acceleration

 

The lack of acceleration and power in your car is another noticeable sign that you have faulty spark plugs in your car that have the potential to misfire. The lack of acceleration means that your engine is unable to ignite and will struggle to increase the power when the driver presses on the gas pedal.

 

Damaged spark plugs that are not working can cause a lack of acceleration and require an immediate replacement in order to keep the engine working at a high level. 

 

• Rough Idling

 

Rough or uneven idling and vibrations felt within the car are another vital sign that shows you might have faulty spark plugs that can misfire. The engine will be running at a lower RPM during idling, but if the spark plugs are damaged, this will produce a higher RPM while idling and increased vibrations that can be felt through the steering wheel and on the floor of the car. Uneven idling and rough idling can cause you to learn how to test spark plug wires. 

How To test Spark Plug Wires With Engine Off

 

The first method of how to test spark plug wires is with the engine off. In this process, there are three steps that you need to follow in order to safely and efficiently test and determine if the spark plug wires are working efficiently/ 

 

• Look For Damage

 

The first step is to look for any visible or physical damage to the wires, such as cuts, lacerations, scorch marks, or burns. If you can't get a good view of the wires or the bots, you need to get a flashlight or move your vehicle to an area of good lighting so that you can see all of the spark plug mechanisms in the car effectively. 

 

All of these parts include the spark plug wires, the cap on top of the spark plug wires, and the distributors. Ensure you visibly inspect and manually examine the insulation around the wires. By physically and visibly inspecting the wires’ health, you can quickly and efficiently learn how to test spark plug wires. 

 

• Check for corrosion

 

When looking at how to test spark plug wires, the next step is to check for any corrosion between the boot and the spark plug and coil. Remove the boot from the spark plug’s top and see where the connection is within the boot. Make sure there is no damage at this connection point that can harm the spark plugs. After this is done, remove the spark plug and inspect for any discoloration. 

 

• Inspect the spring clips

 

The spring clips are the mechanisms that hold the wires within the distributor cap within the spark plug setup. Follow the wires visibly and with your hand away from the cylinder to the attachment point at the distributor. Move the end of the spark plug wire, making sure that the clips are secure and sturdy. If they are unsteady, then damaged clips can cause the wires to slip and not hold their position. Inspecting the spring clips is the final step in how to test spark plug wires when the engine is off.

How to Test Spark Plug Wires With Engine On 

 

• Identify symptoms

 

When looking at how to test spark plug wires with the engine on, the first step is to identify and notice symptoms that are commonly associated with a faulty spark plug wire. A broken or damaged spark plug wire can cause other signs of damage in your car and lead to noticeable signs that something is wrong with your engine or transmission.

 

The most common symptoms of faulty spark plug wires include a rough idle, engine misfiring, radio interference, decreased fuel mileage, failed emissions test, or the check engine light coming on in your dashboard. 

 

• Visual Inspection

 

While the engine is running, you need to visually inspect the engine and how it is running. Sometimes you will be able to determine the root cause of the issue by just looking at the engine while your car is running. Look for any electrical areas around the spark plug wires, listen for abnormal noises, and inspect for visible damage.

 

During this inspection and learning how to test spark plug wires, you need to have someone else rev the engine while you continue to look at it and listen for abnormal changes.

 

• Test Wire Insulation

 

The next step in learning how to test spark plug wires is to use a screwdriver or a long piece of wire to test the electrical currents’ ground source within each spark plug wire. Use the screwdriver down the length of each wire, the coil, and the boots, testing to see if you get an arc from the wire to the screwdriver. If you have an arc from the wire, then you have a defective wire that will need replacing.

 

• Look for arcing of the spark plug wires

 

Fill a bottle with water and spray water along the wires, focusing the water output on the boots that attach to the spark plugs. If you find any arcing around the boot and the spark plug, then turn off the engine and determine the boots’ performance. This step is crucial in determining how to test spark plug wires.

 

• Inspect the inside of the boot

 

The last step in this method of how to test spark plug wires involves inspecting the inside of the boot for carbon tracking. After you have sprayed the wires to determine if there is spark plug racing, looking inside the boot can help you determine the wires’ longevity and lifespan. Check inside for any residue and black marks inside of the boot. If there is a buildup of carbon, this shows that the connection can lead to engine misfiring and damaged spark plug wires.

How to Test Spark Plug Wires With a Meter or Diagram

 

• Locate the resistance rating

 

The first step in how to test spark plug wires with a meter or diagram involves finding the resistance rating of the spark plugs. This is generally shown in the vehicle factory service manual in your car. You can also ask a local mechanic or call the manufacturer if you don't have the manual with you. 

 

• Use an ohm meter

 

An ohm meter is a diagnostic tool that is used to test spark plug wires and check the resistance. This test can determine if the spark plug wire resistance is in line with the recommended guide and preset specifications for your vehicle. Then, remove the wire from the engine by unscrewing the spark plug wire. After this, place one problem on each end of the wire to successfully learn how to test spark plug wires.

 

• See if the wires are routed properly

 

The last step in how to test spark plug wires with a meter or diagram involves analyzing if the spark plug wires are tortured correctly by looking at the spark plug diagram in the service manual. Visibly and manually trace each of the spark plug wires from the connection on the engine block to the spark plug. Make sure you hate each wire going to the spark plug so that you can see if this is causing the problems in your vehicle. 

Conclusion

 

When looking at how to test spark plug wires, there are certain indications that can clue you in to faulty spark plugs. These noticeable signs and symptoms can alert the driver to issues with the sparkplugs, causing performance reductions and problems with the engine and transmission in your vehicle. 

 

Knowing the main methods for testing spark plug wires can help you quickly and effectively diagnose the issue in your vehicle, reducing problems further down the line.