Signs of Faulty Spark Plug Wires (Signs and 3 Tests)
Content
In this article, I will guide you on how to find signs of bad spark plug wires and how to check them.
The spark plug is responsible for supplying the spark needed to ignite the engine. It is usually made from a durable material designed to last for millions of uses. But, like any engine component, it can wear out due to aging, corrosion, or exposure to extreme temperatures.
Prevent further damage to your engine by studying the signs and symptoms of faulty wiring.
Finding Signs of Faulty Spark Plug Wires
The key to preventing further damage is to quickly spot the signs of a bad spark plug.
Damaged spark plug wires have a noticeable effect on a car's engine. Here are the common signs of a bad spark plug wire to look out for:
1. Engine surge
Engine surge is when the car suddenly slows down or accelerates while the accelerator remains stationary.
A bad spark plug causes current leaks and cracks in the ignition wire insulation. This results in a sudden jerk or stop in the transmission of electric current in the motor.
2. Rough idling
Rough idling is usually detected when the vehicle is started.
It is characterized by shaking, vibration or bouncing throughout the vehicle. It can also cause an intermittent or slipping sound from the engine.
Please note that some problems can cause uneven engine idling. This is not a sure sign of faulty spark plugs.
3. Engine misfiring
Engine misfiring is the most worrying sign of faulty spark plugs.
Engine misfiring is caused by interference in combustion. A bad spark plug does not properly transmit the spark required for the ignition or distributor.
4. Engine delay
A bad spark plug cannot deliver electrical current all the time.
Many vehicle owners complain that their engine lacks power or stalls when accelerating. This is due to the intermittent supply of electrical current from the spark plugs.
Checking the condition of the spark plug wires
Different engine problems can cause the same set of signs and symptoms.
Checking the condition of the spark plug wires is the best way to confirm the cause of engine problems. Several tests can be carried out, from a simple visual inspection to extensive checks to check for faulty plug wires.
Check the condition of the spark plug wire
The first test a vehicle owner should do is a visual inspection of the condition of the spark plug wires.
There are two things to look out for when inspecting spark plug wires: cracked or melted insulation. Spark plug wire insulation dries out over time. It can also be damaged by contact with hot engine parts.
Check the entire length for signs of damage to the spark plug wires.
Inspect the wired connection
Incorrectly connected wires can cause engine problems such as engine surges and misfires.
Cars come with a manual that shows the route and wiring of the engine. Compare the correct wire connection in the manual with the current connection on the motor. The connection should be similar, if not exactly, to what is listed in the manual.
Re-wiring is necessary if the current wire connection is not similar to that specified in the instructions.
Inspect the ignition wires and spring chips.
Shut off the engine and inspect each ignition wire.
Remove the wires from the engine and inspect them on the ground. Remove dirt with a clean rag to see any damage. Check for corrosion the insulation between the ignition coils, distributor, covers and wires. After that, check if the spring chips are installed on the spark plug wires in the distributor.
Proceed to the following checks if there is no visible damage to the spark plug wires.
Check for electrical leaks
Reinstall all removed wires and components and start the engine.
A clicking noise when the engine is running is a common sign of wiring leaks. Listen for clicks around wires, distributor and ignition coils.
Be careful not to touch the wires while the engine is running to avoid electric shock.
Resistance test
A multimeter is needed to check the resistance.
Disconnect the spark plug wires and attach multimeter leads to each end. Check if the measured resistance is within the range specified in the vehicle owner's manual. Connect wires back to motor if resistance is within specification.
Replacement of wires and leads is necessary if the measured resistance does not correspond to the nominal value. (1)
Spark check
A spark tester is needed to test the spark.
Remove the spark plug wire from the spark plug. Connect one end of the wire to the spark meter and the other end to engine ground. Turn on engine ground. Look for the presence of a spark across the spark gap.
A weak spark is difficult to see in daylight and is orange or red. On the other hand, a good spark is indicated by the presence of a blue-white spark visible in daylight. The ignition system is good if a good spark is observed. (2)
Remove the coil wire from the distributor cap if no spark is observed. Connect the end of the distributor coil wire to the spark meter. Start the engine and watch for a spark. If a spark was seen, bad spark plugs or problems with the distributor cap or rotor can be expected.
Summing up
Vehicle owners usually know when something is wrong with their vehicles.
Car owners are often concerned about problems with vehicle operation, such as reduced gas mileage and uneven engine idling. The key to preventing engine damage is to find the cause of the problem.
Watch for any symptoms of faulty plug wires to determine if there is a problem with the vehicle's electrical and ignition system. Several tests can be done on the spark plug wires to confirm if this is causing problems.
Vehicle owners can begin the necessary repairs as soon as they confirm the presence of faulty spark plug wires.
Take a look at some of our articles below.
- How to crimp spark plug wires
- How long do spark plug wires last
- How to arrange spark plug wires
Recommendations
(1) measured resistance - https://www.wikihow.com/Measure-Resistance
(2) ignition system - https://www.britannica.com/technology/ignition-system
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