Although the automotive industry has made drastic mechanical and technological progress throughout history, there is one element that all vehicles equipped with internal combustion engines have in common: the ignition system.
If you take your precious vehicle seriously, it is helpful to know how the different types of ignition systems work, as well as their advantages and disadvantages, in order to choose the right spark plug that works most efficiently given the performance requirements of the ignition system.
Although almost all major components of a car have undergone improvements over the years, the basic principles of the ignition system have not changed for nearly a century.
In essence, it takes the electrical voltage from the battery, converts it into a much higher voltage, and then transfers this electrical current to the engine’s combustion chamber, igniting the compressed mixture of fuel and air to create combustion. This combustion generates the energy needed to operate your car.
That said, the method by which the spark is created and distributed has greatly improved thanks to technological advances. Currently, there are four types of ignition systems used in most cars and trucks, in order of invention: conventional breaker point (mechanical) ignitions, high-energy (electronic) ignitions, distributorless (waste spark) ignitions, and coil-on-plug ignitions.
Breaker point (mechanical) and high-energy (electronic) ignitions are distributor-based ignitions. Another way to classify them is therefore into three broader types of ignition systems: distributor-based, distributorless, and coil-on-plug systems.
In this comprehensive guide, we will look at how each system works, as well as the resulting advantages and disadvantages, based on what it means for your engine’s performance and maintenance requirements.
What is the purpose of the ignition system?
When you put your key in your vehicle’s ignition and turn it, your engine starts and continues to run. Have you ever wondered what the complete process is behind such a simple action?
Let’s get back to basics: your engine produces energy to power your car by creating combustion, or an explosion, inside its combustion chamber, hence the name “internal combustion engine”. To generate such combustion, the ignition system plays a major role: your spark plugs provide the electrical spark that ignites the air-fuel mixture that powers the combustion chamber.
For the ignition system to function correctly, it must be able to perform two tasks efficiently and accurately at the same time.
Create a spark strong and hot enough
The first task is to create a powerful spark that can jump the gap between the spark plugs. In other words, the ignition system must increase the voltage from the battery’s 12 volts to at least 20,000 volts, which is necessary to ignite the compressed air and fuel mixture in the combustion chamber to create an energy-generating explosion.
To achieve such a voltage surge, the ignition systems of all cars, except diesel models, use an ignition coil composed of two coils of wire wound around an iron core, called the primary winding and secondary winding. The ignition coil acts as an electrical power transformer.
The role of the ignition coil is to create an electromagnet by passing the 12 volts supplied by the battery through the primary winding. When the vehicle’s ignition system trigger switch cuts power to the ignition coil, the magnetic field collapses. In doing so, the secondary winding captures the collapsing magnetic field from the primary winding and converts it into 15,000 to 25,000 volts.
It then supplies this voltage to the spark plug, thus creating combustion in the engine’s combustion chamber, thereby generating the energy needed to start and run your vehicle’s engine. For the necessary spark to occur, the converted voltage delivered to the spark plug must be between 20,000 and 50,000 volts.
Ignite the spark at the right time
Simultaneously, the ignition system also has the essential role of ensuring that the spark fires at the right time during the compression stroke to maximize the power generated by the ignited air-fuel mixture. In other words, sufficient voltage must be delivered to the right cylinder at the right time, and this operation must be performed frequently.
All components work with precision and harmony for your engine to achieve optimal performance. Even the smallest timing error in a single part will lead to engine performance problems and, if prolonged, can even cause permanent damage.
The ignition system must provide sufficient spark to the correct cylinder. To ensure precise ignition timing, engineers have used several methods, which have evolved over the years.
Early ignition systems used fully mechanical distributors to control ignition timing, followed by hybrid distributors equipped with semiconductor switches and the Engine Control Module (ECM), essentially a type of simple process computer, to distribute electrical power to each cylinder.
To counter the disadvantages of these early distributors, 100% electronic ignition systems emerged, the first of which was a distributorless ignition system, where the distributor was eliminated.
The latest invention, coil-on-plug ignition systems, significantly improved ignition timing by using an improved ignition coil that produces much higher power and generates a much hotter spark.
What is the purpose of each component of the ignition system
Battery
When the engine runs, it also operates the alternator which generates electricity to recharge the battery. Your car’s battery stores electricity and releases it as direct current.
The battery provides twelve volts of direct current. However, to obtain a spark enabling combustion, the spark plug needs to be supplied with a voltage between 20,000 and 50,000 volts. To allow for such a significant voltage increase, the ignition coil is required.
Ignition Coil
The ignition coil acts as an electrical power transformer. Early mechanical ignition systems rely on a coil to convert the battery’s low voltage into the high voltage required by the spark plugs.
The electrical transformation of the ignition coil works on a principle called magnetic induction. In a traditional transformer, the primary coil receives energy, i.e., direct current from the batteries. However, this charge through the primary coil is periodically interrupted. This interruption is caused by the distributor in early distributor-based ignition systems, and by a computer for more precise timing in later ignition systems. The role of the distributor will be discussed later.
The voltage in the primary coil produces a magnetic field. The periodic disruption of the current received by the primary coil causes the constant collapse of the magnetic field produced by the primary coil. Such significant movements of the primary coil’s magnetic field cause the secondary coil to create a burst of high-voltage energy at once.
The voltage generated by the secondary coil depends on the ratio between the number of turns in the primary coil and the number of turns in the secondary coil. If the secondary coil has twice as many turns as the primary coil, the output voltage will be twice the input voltage.
Thus, to increase the voltage from 12 volts to the at least 20,000 volts that spark plugs need, in a car’s ignition coil, the secondary coil has tens of thousands of times more turns than the primary coil.
Distributor
Here is how the distributor creates the aforementioned periodic discrete charges supplied to the primary ignition coil. The distributor contains a “breaker point” that grounds the primary coil circuit. This point is connected to ground by a lever. The lever is moved by a cam connected to the distributor shaft. This opens the primary coil circuit and causes the collapse that triggers the high-voltage bursts in the secondary coil.
Furthermore, while the battery and ignition coil provide the power, the distributor does significant work, precisely determining where and when this power goes to each spark plug.
The distributor contains many parts, the most important of which are a rotor that spins at engine speed and several “terminals” mounted on the distributor cap. The electrical current from the ignition coil is supplied to the rotor.
The rotor spins, and when the tip of the rotor approaches one of the terminals, an electrical arc jumps to that terminal. From there, the energy flows along a spark plug wire to the associated spark plug, thus timing the firing of each plug.
Spark Plugs and Their Wires
Spark plug wires, also called ignition wires, are insulated wires that carry energy to the spark plugs so that they can finally create the spark that causes combustion.
The spark plug consists of an insulated ceramic body with a central conductive metal core in the center. There is a gap between this central metal core and the tip of the electrode that connects to the metal base of the spark plug. Electricity arcs or jumps across this gap, causing the spark.
The importance of the ignition system
The key takeaway is that if the ignition system does not function properly and accurately, your car may struggle to start or not run at all.
Worn spark plugs and faulty ignition system components will affect your engine’s performance, creating a wide range of engine problems including hard starting, misfires, lack of power, poor fuel consumption, and even permanent damage if the issues are not resolved in time. Also note that these engine problems caused by faulty ignition systems can damage other critical components of your vehicle.
Regular maintenance of your ignition system is therefore essential to ensure optimal engine performance and thus smooth and safe driving. In this case, what is a sufficient frequency? At least once a year, you should perform a visual inspection of your ignition system components to check for signs of wear or failure, and then replace them immediately if necessary.
Regarding your spark plugs, be sure to inspect and replace them at the interval recommended by your vehicle’s manufacturer. Again, given the importance of the ignition system, preventive maintenance is crucial to maximize your engine’s performance and lifespan.
Understanding the 4 Types of Ignition Systems
1 Distributor-Based Breaker Point Ignition (Mechanical)
History
The oldest ignition system is the conventional breaker point ignition system, sometimes called the mechanical ignition system. It has been used since the early days of the automotive industry, particularly through the 1970s.
It is one of the two types of ignition systems that use a distributor, called distributor-based systems. Unlike the three other types of ignition systems described later, the breaker point ignition system is fully mechanical, hence its second name.
Let’s see how they work, and then, based on that, we will look at the resulting advantages and disadvantages for this type of ignition system. We will go into detail in this section, as the mechanical breaker system is the first invention and thus the basis for all subsequent models. You need to understand the operation of this system well to see the advantages and disadvantages of the later improved systems.
A Brief Description of Distributor Ignition
The first two types of ignition systems, the breaker point system and the electronic system, are both distributor-based, unlike the other two distributorless systems. So, let’s learn the basics of how a distributor-based system works.
A distributor is an enclosed rotating shaft with mechanically timed ignition. The main function of the distributor is to route the secondary, or high-tension, current from the ignition coil to the spark plugs in the correct firing order and for the appropriate duration.
In the case of a fully mechanical distributor, the distributor is connected to the camshaft by gears and driven by the camshaft. Inside, the multi-lobe cam on the distributor shaft moves other parts of the distributor, essentially acting as a mechanical switch that starts and stops the power flow to the ignition coil.
Once the coil generates sufficient voltage, it moves to the top of the coil and into the top of the distributor cap. There, a rotating disc attached to the distributor shaft distributes the electrical current to each of the spark plug wires in order. The current travels along the spark plug wires to the spark plugs and causes ignition.
How Breaker Point Ignition Works
A distributor-based breaker point ignition system has two electrical circuits, the primary and secondary circuits.
An ignition coil consists of two coils of wire wound around an iron core, called the primary winding, or primary coil, and secondary winding, or secondary coil.
The primary circuit consists of the primary coil, the “breaker points”, and the vehicle’s batteries. It operates only on the battery’s low current and is controlled by the breaker points and the ignition switch.
Meanwhile, the secondary circuit consists of the secondary windings of the coil, the high-tension coil wire on external coil distributors, the spark plugs, the spark plug wires, the distributor rotor, and the distributor cap.
When the ignition key is turned on, the primary coil receives low-tension direct current from the batteries, which passes through the distributor’s breaker points and returns to the battery. This current flow forms a magnetic field around the ignition coil.
Now here is how the “breaker point” comes into play.
As mentioned above, the distributor contains a “breaker point” that grounds the primary coil circuit. This breaker point is connected to ground by a lever, which is moved by a cam connected to the distributor shaft.
Through the distributor rotor spinning at engine speed, when the engine turns, the cam on the distributor shaft rotates until the high point of the cam causes the breaker point tips to separate. Instantly, this sudden separation stops the flow of current through the primary coil.
This causes the magnetic field produced by the primary coil around the coil to collapse. The capacitor absorbs the energy and prevents electrical arcing from forming between the breaker points at each separation. In other words, the capacitor therefore plays a role in the rapid collapse of the magnetic field, necessary to create a high voltage surge in the secondary coil.
Such sudden and continuous changes in the primary coil’s magnetic field cut across the secondary coil, creating a voltage surge high enough to bridge the gaps between the rotor and the distributor terminals, as well as the gaps between the spark plug electrodes.
Assuming the entire system is properly timed, the spark reaches the air-fuel mixture in the designated cylinder at the precise moment, and