What is an Ignition Coil? | Signs of Bad Ignition Coil

What is an Ignition Coil?

An ignition coil is an induction coil in a car’s ignition system that converts the voltage of the battery into thousands of volts required to produce an electrical spark in a spark plug to ignite the air-fuel mixture. The ignition coil is also known as a spark coil.

ignition coil

Few types of ignition coils contain an internal resistor, while others types depend on an external resistor or resistor wire to control the current flow from the battery of the vehicle into the coil.

The high voltage wires that go from the distributor to each spark plug and the wires that go from the ignition coil to the distributor are known as the high voltage wires or spark plug wires.

The ignition coil has extremely high reliability. However, it may damage due to multiple reasons.

The vehicle vibration and heat may damage the coil insulation and winding. This can cause a short or open circuit in the primary or secondary winding. However, voltage overload badly damages the ignition coils. The voltage overload may be due to bad plug wires or a bad spark plug.   

The ignition coil has two sets of windings:

  1. The primary coil windings contain hundreds of turns of heavy wires.
  2. The secondary coil windings contain thousands of turns of thin wire.

Older cars use a distributor and a single coil to deal with all spark plugs. However, the latest vehicles don’t have distributors because they control the ignition coil electronically.

Working Principle of Ignition Coil

The ignition coil contains a laminated iron core and two coils of copper wire. Two copper wire coils are used to surround the laminated iron core. The ignition coil contains two types of windings:

  1. Primary windings
  2. Secondary windings

Working of Ignition Coil

 The ignition coil works in the following way:

  1. As you turn on the car ignition key, the car battery generates a low voltage current. This current flows from the primary windings to the breaker point and back to the battery. This flow of current generates a magnetic field around the coil.
  2. The secondary circuit contains secondary winding, the spark plugs, the spark plug leads, the distributor rotor, and the distributor cap. When the engine coil turns, the distributor shaft cam also rotates until the high points on the cam cause the breaker points to break swiftly.
  3. When the contact opens in the contact breaker, the current in the primary winding breakdowns. This also destroys the magnetic field in the core. This unexpected breaking of the magnetic field creates a very high voltage (i.e., 50,000 volts) in the secondary windings.
  4. This high voltage current is then delivered to the spark plug via the distributor to create an ignition spark.

Types of Ignition Coils

The ignition coil has the following major types:

  1. Conventional Ignition Coils
  2. Electronic Ignition Coils
  3. Distributor less Ignition Coils
  4. Coil-on-Plug Ignition Coils

1) Conventional Ignition Coil

In these ignition coils, the battery transfers current to the primary circuit. As the current flows through the primary coil winding, it generates a magnetic field.

If the points are open, it means you have a broken electric circuit. This leads to the stabilization of the magnetic field. When this stable force goes through the secondary coil windings, it makes an electric current between them.

The current from the secondary coil windings flows to the distributor cap from where it enters the spark plug in just a few seconds. When the ignition point breaks down, it changes the ignition timing and reduces the efficiency of the engine.

2) Electronic Ignition Coil

The maximum features of the electronic systems are very similar to conventional systems. However, the electronic ignition coil uses an electronic system instead of distributor cams and points. It also requires a pickup coil to send signals to the control module.

Distributor shafts use to create a certain amount of ” stroke” after some specific meters. So, gear wear always disturbs the proper ignition timing and requires the development of a mechanical ignition system.

3) Distributor less Ignition Coil (DIS)

These types of ignition coils have the ability to draw more power from multiple coils due to their design.

They have a magnetic triggering device that uses to sense crankshaft position and engine speed. The system determines ignition timing based on two shaft position sensors and an engine control unit (ECU). The crankshaft position sensor monitors the position of both shafts every time and sends this information to the ECU.

4) Coil-on-Plug Ignition Coil (COP)

This system contains all of the electronic controls found on direct ignition systems. However, instead of two cylinders operating one coil, each (COP) coil is coupled to a single cylinder. As a result, some ignition systems generate sparks of up to 47,000 volts or more.

Signs of Bad Ignition Coil

1) Poor Fuel Economy

A reduction in the vehicle fuel economy is one of the famous signs of a bad ignition coil. When the ignition coil damages, it doesn’t supply power to the spark plug according to its requirement due to that vehicle’s engine works hard and consumes more fuel than usual.  

2) Backfiring

The vehicle backfiring is an initial sign of the ignition coil failure. The backfiring occurs when the engine expels unused fuel from the exhaust pipe. The vehicle may face backfiring issues due to some other reasons, such as engine oil leaks, coolant leaks, or a bad head gasket. 

When you notice a vehicle backfiring issue, immediately inspect and fix the issue; otherwise, it can result in serious damage to the exhaust, which can lead to avoidable and expensive repairs.

3) Vehicle Stalling

Ignition coils failure can cause the vehicle to send an irregular spark to the spark plug, causing the vehicle to stall. As the vehicle stalls, it can be forced to shut down completely and restart.

4) Loss of Power

The reduction in the engine power is one of the main symptoms of a bad ignition coil. When the ignition system goes bad, the ignition coils don’t deliver sufficient power to the spark plug; due to that, it doesn’t produce a powerful spark.

When the plug doesn’t produce a spark according to requirements, the air-fuel mixture inside the combustion chamber doesn’t burn efficiently.

When the air-fuel mixture doesn’t burn efficiently, you will see a reduction in the engine power, and the car slows down. In the event of a power outage, drive your vehicle to a mechanic and fix the problem.

5) Check Engine Light ON

If the car stalls or is difficult to start, the check engine light will illuminate. As the ignition coils illuminate, the Check Engine Light starts illuminating. It may illuminate due to some other reasons such as a damaged combustion chamber, faulty head gasket, or blown head gasket.  

6) Hard to Start

In order for the engine to start and the car to run, the spark plug must generate a spark at the right time. When the ignition coil goes bad, it doesn’t supply the desired power to the spark plug to generate a spark; due to that, the engine will be hard to start.

8) Spluttering and Coughing sounds

When starting the engine, a bad ignition coil may generate a stutter or cough sound. This sound comes from a cylinder in which the air-fuel mixture is not igniting during the ignition process.

9) Vibration

Vehicle vibration is one of the common symptoms of ignition coils failure. You may also notice that your vehicle jerks forward as you increase its speed.

 Causes of Ignition Coil Failure

1) Damaged or worn spark plugs

As the spark plug wears out, the ignition coil starts to work at higher power. To prevent the ignition coils from being damaged, you must maintain the spark plug in good condition.

When the spark plug wears out, the gap between each plug widens. That means the coil has to deliver a higher voltage than usual to fill the gap. This extra stress on the ignition coil can cause a voltage surge that can overheat and eventually fail.

2) Engine Overheating

The engine overheating is one of the most common causes of ignition coil damage.

3) Vibration

Vibration can damage the ignition coil windings and insulation and cause short circuits or damage to the secondary windings.

4) Wear and tear

Wear & tear is a common cause of ignition coil failure. The wear & tear degrades the insulation between the secondary and primary coil windings and the primary coil. Poor insulation can cause the coil to overheat.

FAQ Section

What is the Function of the ignition coil function?

The ignition coil works very similarly like a transformer. With two-layered coils, the ignition coil converts electrical energy from the vehicle power source into a high voltage and transfers it to a spark plug, which uses this voltage to generate a high-voltage spark.   

What are the applications of the Ignition coils?

The ignition coils are most commonly used in the petrol engines such as cars, motorcycles, buses, tractors, etc.  

What are the parts of the ignition coil?

The ignition coil has the following major parts:

  1. Iron core
  2. Primary Winding
  3. Secondary Winding

How to Identify Failure of Ignition Coil?

The different symptoms of the ignition coil failure are:

  • Engine shaking
  • Backfiring
  • Vehicle stalling
  • Starting problems
  • Engine misfiring
  • Less fuel economy
  • Reduction in engine power
Read More
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  2. Signs of bad Gearbox
  3. Symptoms of bad Spark Plug

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