Symptoms of a Bad Ignition Coil: All that You need to know

As a vital component of a car’s ignition system, the ignition coil is responsible for powering the spark plugs and igniting the fuel-air mixture in the engine. A faulty ignition coil can lead to serious performance issues and potentially leave you stranded on the side of the road. In this article, we will discuss the symptoms of a bad ignition coil and how to identify and address them.

Whether you are a seasoned mechanic or a car owner, understanding these symptoms can help you keep your vehicle running smoothly and avoid costly repairs. So, let’s dive in and learn all about the tell-tale signs of a bad ignition coil.

What Does an Ignition Coil Do?

An ignition coil is a crucial component in the ignition system of a vehicle. Its main function is to convert the low voltage from the battery into the high voltage needed to create the spark that ignites the fuel-air mixture in the engine’s cylinders. This process is essential for the engine to start and run smoothly.

The basic structure of an ignition coil consists of two coils of wire, the primary and secondary winding, placed next to each other around a metallic core. The primary winding has a few hundreds of turns of thick wire, while the secondary winding has thousands of turns of thinner wire. This construction allows the coil to facilitate the transformation of the battery’s low voltage (typically 12 volts) into the high voltage (about 25,000 volts) required to generate a spark.

The function of an ignition coil can be divided into two main phases: charging and firing. During the charging phase, a low voltage current from the battery flows through the primary winding of the coil. The metallic core within the coil acts as an electromagnet, increasing the magnetic field around the primary winding. This causes the energy stored in the primary coil to increase. The charging phase is essential to build up the necessary energy to produce a powerful spark.

Once the energy is stored in the primary winding, it is then released during the firing phase. When the power supply is suddenly cut off, the magnetic field collapses, causing electrons to flow from the primary to the secondary winding. This sudden movement of electrons creates a high voltage within the secondary winding, which then travels to the distributor and ultimately to the spark plugs.

The distributor is responsible for directing the high voltage to the correct spark plug, based on the engine’s firing order. As the high voltage reaches the spark plug, a spark will jump across the gap between the electrodes, igniting the fuel-air mixture in the engine’s cylinder.

An efficient ignition coil is vital for the proper functioning of an engine. If any component of the ignition coil, such as the primary or secondary winding, is damaged or worn out, it can affect the performance of the engine and even prevent it from starting. In older vehicles, an ignition coil could fail due to excessive heat, but modern ignition systems are designed to last the lifetime of a vehicle.

Symptoms of a Bad Ignition Coil

A car’s ignition coil is responsible for providing the high voltage needed to ignite the fuel and air mixture in the engine’s combustion chamber. When the ignition coil is not functioning properly, it can cause various symptoms that can affect the performance and reliability of the vehicle.

Here are some common symptoms of a bad ignition coil:

Engine misfiring: The most common symptom of a bad ignition coil is engine misfiring. This happens when the coil fails to provide the necessary spark to ignite the fuel and air mixture in the engine’s cylinders. As a result, the engine will run rough and may even stall.
Difficulty starting the engine: If the ignition coil is failing, it may be difficult to start the engine. This is because the coil is not providing enough spark to ignite the fuel and air mixture. You may need to turn the key multiple times or hold it in the crank position for an extended period before the engine starts.
Decreased fuel efficiency: A bad ignition coil can also cause a decrease in fuel efficiency. This is because the engine is not functioning at its optimum level, and the fuel and air mixture is not being properly ignited. As a result, the engine will use more fuel to produce the same amount of power.
Engine stalling: A deteriorating ignition coil can cause the engine to stall while driving. This is a dangerous situation as it can leave you stranded on the road. If the coil is not providing enough spark to keep the engine running, it will shut off, and the vehicle will come to a halt.
Check engine light: A failing ignition coil can trigger the check engine light to turn on. This light is connected to the vehicle’s computer system and is designed to alert the driver when there is a problem with the engine or its components. If the check engine light is on, it is best to have the vehicle inspected by a mechanic to determine the cause.
Rough idling: If the ignition coil is not functioning properly, it can cause the engine to idle roughly. This means that the engine will vibrate and shake while the vehicle is stationary. It may also produce a loud knocking or sputtering noise.
Engine backfiring: In some cases, a bad ignition coil can cause the engine to backfire. This is when the fuel and air mixture is ignited in the intake manifold instead of the combustion chamber. Backfiring can cause damage to the engine and exhaust system, so it is important to address the problem immediately.

How to Test Ignition Coil

An ignition coil is an essential component of the ignition system in an internal combustion engine. It is responsible for converting low voltage from the battery into high voltage necessary to create the spark in the spark plugs.

A faulty ignition coil can lead to engine misfires, loss of power, and poor fuel efficiency. As a mechanical engineer, it is important to know how to test an ignition coil to ensure its proper functioning. Below are the steps to test an ignition coil.

Step 1: Gather the Necessary Tools

To test an ignition coil, you will need a digital multimeter, an insulated screwdriver, and the manufacturer’s service manual for your specific vehicle make and model.

Step 2: Prepare the Vehicle

Before testing the ignition coil, make sure that the vehicle is parked in a safe and well-ventilated area. Ensure that the engine is turned off, and the key is removed from the ignition.

Step 3: Locate the Ignition Coil

The ignition coil is typically located near the engine’s cylinder head and is connected to the spark plugs through insulated wires.

Step 4: Disconnect the Ignition Coil

Using the insulated screwdriver, disconnect the ignition coil from the spark plug. Make sure to handle the ignition coil carefully as it carries high voltage.

Step 5: Set the Multimeter

Set your multimeter to the ohms or resistance range. The ideal range can vary depending on your vehicle’s make and model, so refer to the service manual for the recommended range.

Step 6: Test the Primary Winding

The primary winding is the coil’s input side, which receives low voltage from the battery. Place the multimeter probes on the positive and negative terminals of the ignition coil. The resistance reading should be between 0.4 to 2 ohms, but again, refer to the service manual for the exact specification for your vehicle.

Step 7: Test the Secondary Winding

The secondary winding is the coil’s output side, which produces high voltage for the spark plugs. Place one probe on the positive terminal and the other on the high-voltage terminal of the coil. The resistance reading should be between 6,000 to 30,000 ohms, depending on the vehicle’s make and model.

Step 8: Compare the Readings

Compare the resistance readings from both the primary and secondary windings with the specifications provided by the manufacturer. If the readings are significantly different, the ignition coil may be faulty and needs to be replaced.

Step 9: Check for Spark

If your multimeter readings are within the recommended range, you can further check the ignition coil’s functionality by performing a spark test. Reconnect the ignition coil to the spark plug, hold the spark plug against a conductive surface (engine block), and crank the engine. If the spark plug produces a bright spark, then the ignition coil is functioning correctly.

Step 10: Replace the Ignition Coil

If the ignition coil fails the multimeter tests or does not produce a spark, it needs to be replaced. Follow the manufacturer’s instructions for proper installation of the new coil.

Conclusion

In conclusion, a bad ignition coil can cause a variety of symptoms that can affect the overall performance and safety of your vehicle. It is important to pay attention to any warning signs such as engine misfires, stalling, and decreased fuel efficiency to determine if your ignition coil needs to be replaced.

Regular maintenance and timely replacement of worn-out ignition coils can help to prevent costly repairs and keep your vehicle running smoothly. By understanding the symptoms of a bad ignition coil, you can stay ahead of any potential issues and ensure the longevity of your vehicle. Keep an eye out for these signs and seek professional assistance if needed to keep your car running at its best.

Frequently Asked Questions

What is the role of an ignition coil in a car’s ignition system?

The ignition coil is a crucial component that converts low voltage from the battery into high voltage needed to create a spark, which ignites the fuel-air mixture in the engine’s cylinders. This process is essential for starting and running the engine smoothly.

What are the main components of an ignition coil?

An ignition coil consists of two coils of wire, the primary and secondary winding, around a metallic core. The primary winding has fewer turns of thick wire, while the secondary winding has more turns of thinner wire. This design enables the transformation of low voltage to high voltage.

What are the phases of an ignition coil’s function?

The ignition coil operates in two main phases: charging and firing. During the charging phase, low voltage from the battery flows through the primary winding, creating a magnetic field. In the firing phase, the stored energy is released, generating a high voltage spark that ignites the fuel-air mixture in the engine’s cylinders.

What are the symptoms of a bad ignition coil?

Common symptoms include engine misfiring, difficulty starting the engine, decreased fuel efficiency, engine stalling while driving, the illumination of the check engine light, rough idling, and engine backfiring.

How does a bad ignition coil affect engine performance?

A faulty ignition coil can lead to incomplete combustion, resulting in engine misfires, decreased fuel efficiency, and rough idling. In severe cases, it may cause the engine to stall, leading to potential safety hazards.

Why is it important to address a failing ignition coil promptly?

Ignoring symptoms of a bad ignition coil can lead to severe engine damage, increased fuel consumption, and the risk of being stranded on the road. Prompt replacement can prevent these issues and maintain the overall performance and safety of the vehicle.

How can I test if my ignition coil is functioning properly?

You can test the ignition coil using a digital multimeter. Steps include preparing the vehicle, locating the ignition coil, disconnecting it, setting the multimeter, and testing both the primary and secondary windings. Comparing the readings with manufacturer specifications helps determine if the ignition coil is faulty.

What should I do if my ignition coil fails the tests?

If the ignition coil fails the tests or produces abnormal readings, it should be replaced. Follow the manufacturer’s instructions for proper installation of the new coil to ensure optimal engine performance.

Can a bad ignition coil be responsible for the check engine light turning on?

Yes, a failing ignition coil can trigger the check engine light to illuminate. If the light is on, it is advisable to have the vehicle inspected by a mechanic to identify and address the underlying issue.

How can regular maintenance help prevent ignition coil issues?

Regular maintenance, including timely replacement of worn-out ignition coils, can prevent symptoms of a bad ignition coil and costly repairs. By paying attention to warning signs and seeking professional assistance when needed, you can ensure the longevity and optimal performance of your vehicle.