Ignition System

Ignition System

The ignition system of an internal combustion engine is an essential part of the overall engine system. It generates a spark or a very high voltage to ignite a fuel-air mixture in the engine’s combustion chamber. The system also controls the timing of the spark/voltage to ensure it occurs at the right time and is sent to the correct cylinder. These systems are made of two circuits which work together to create an electric spark at the spark plugs. These circuits are:

• The primary circuit – this circuit operates on low voltage (12 to 14.5 volts) and is responsible for producing a signal to fire the spark plug and sending the signal to the ignition coil. The ignition coil converts this 12/14.5-volt signal into a high volt charge.
• The secondary circuit – this is the high voltage section of the ignition circuit. Once the voltage is stepped up, it goes through this circuit and is then directed it to the correct spark plug at the right time.

The Basic Components of an Automotive Ignition

The ignition circuits are made of various components designed to achieve specific functions on the system. These components are:

Battery – the battery provides electric power for the circuit.
Ignition switch – this component is normally mounted on the dashboard or steering column. It controls the current flowing through the battery and the ignition.
The ignition coil – the coil features a metal casing containing two sets of wires on a central iron core. This electromagnetic device converts battery voltage into high-tension current (30,000 volts and greater).
The distributor – this unit directs the flow of high-voltage current from the coil and sends it to each spark plug. It has a metal bowl that contains a central shaft which is often driven by the camshaft. The bowl houses the capacitor, distributor cap, contact-breaker points, and rotator arm.
Spark plugs – these devices provide an air gap in the combustion chamber for an electric arc. The high-tension current from the distributor flows through the spark plug then generates a spark as it passes through the air gap to the side electrode. The spark then flows through the spark plug body and the engine, then back to the coil, completing the circuit.

Types of Automotive Ignition Systems

Automotive ignitions have evolved over the years to deliver improved and more powerful performance. Today, there are three main types of automotive ignitions and despite their differences in components and technology, they operate on the same basic principle.

Here’s an overview of the three types of systems:

1. The breaker-point ignition

In this type of ignition, the distributor cam and shaft rotate when the ignition switch is turned on causing the distributor cam to close and open the contact points. Since contact points of this ignition are connected to the primary windings, they make and break the primary circuit. When the contact breakers are closed, the current produces a magnetic field in the coil’s core. When the points open, the current stops flowing causing the magnetic fields generated in the coil to collapse. The change of magnetic flux produces a high voltage in the secondary windings that causes the gap in the spark plug to arc and ignite the fuel.

The biggest drawback of breaker-point systems is that they require regular maintenance to compensate for wear and tear.

2. Electronic ignition

The main difference between the breaker-point ignition and the electronic ignition is in the primary circuit. The primary circuit in a breaker-point system is open and closed by contact breakers while that of the electronic ignition is open and closed by an electronic ignition control module.

This type of system is maintenance-free as it doesn’t have moving parts, has more power output and is more fuel efficient. Types of the electronic ignition include capacitance discharge ignition (CDI), piezo-electric ignition, the Texaco system, and transistorized system.

3. Distributorless/Direct system

This type of system is common in modern engines. It doesn’t have a distributor but instead has an ignition coil mounted on top of the spark plug. The timing of the spark plug is controlled directly by the engine control computer or by an ignition module.

The major components of the distributorless system are an electronic control module, a magnetic sensor, coil packs, and a crankshaft reluctor ring.

How an Ignition System Can Improve A Car

These systems degrade with age and mileage, resulting in inconsistent spark delivery or misfires. Ignition problems can also cause a rough idle, loss in power and acceleration, reduced fuel economy and even stalling.

Upgrading the system with high-quality components will deliver a more powerful spark, resulting in increased engine efficiency and performance.