NEWS/PRESS

How An Ignition System Works

by Kelli Murrow

As modern vehicle features evolve, the purpose remains the same. At its core, the modern automobile is identical to that of the first car made with an internal combustion engine by Karl Benz in the 1880s: to get from one place to another faster and easier than using two legs to carry us.

Like that first 3-wheeled model, getting the car to start remains one of the most important features of any vehicle. Read on to learn more about how a car ignition system works.

Electronic Ignition Systems

Modern cars are mostly built with electronic ignition systems. In the past, older ignition systems were as simple as turning the key to move a wire to form a connection.

 The major components of automobile ignition systems include: 

  • Ignition Switch
  • Ignition Coil
  • Distributor
  • Ignition Points (and their replacement in modern ignition systems)

 Of course, there is much more to learn about each component of an ignition system. PerTronix has all of the information and parts needed for any car or engine. But—let’s start with the basics.

How an Electronic Ignition System Works

Modern cars use an electronic ignition system. For example, the internal combustion engine requires a high-energy spark to jump the spark plug gap at a precise time.

This precise time is based on the moment when the fuel (i.e., gasoline) and air are mixed in the cylinder and ready to be ignited, causing a small explosion. The energy from this explosion is directed toward pushing the piston down, which turns the crankshaft. Then, through the transmission, driveshaft, and the differential.

However, a lot happens between turning the key to the ignition system and the small explosion within the cylinder.

Starting an Electronic Ignition System

To start this entire system, you need a battery. The battery stores the energy until it is needed to start the car.

Normally, when a car is sitting and the ignition is off, the battery is not connected to the system and holds energy. However, once the ignition key is turned on, a circuit is completed, allowing the battery’s electricity to start flowing.

In cars with a push-button start, a small computer in the ignition switch sends a signal telling the battery to start releasing energy into the ignition system while activating the starter.

How Does an Ignition Switch Work?

The ignition system depends on completing a circuit for the battery so that energy can flow from the battery to the electronic ignition coil, electricity’s next stop on its way to the spark plug.

Any ignition switch is going to work just like the light switch in a home. When the switch is in one position (either by turning the key or pressing the button on a key fob), a wire makes a connection closing the circuit and allowing electricity to flow. When you turn off the key or press the button on the key fob, the same wire moves away from its contact stopping the flow of electricity.

This is the basic change that occurs in every modern electronic ignition system.

How Does an Ignition Coil Work?

The coil is a metal shell with two sets of wires inside wrapping around each other. Once the ignition system is activated, the electricity begins to flow from the battery to the ignition coil. By passing the electricity through this ignition coil, the low-voltage electricity coming from the battery is converted to the high-voltage needed to jump the spark plug gap and ignite the air fuel mixture.

In most modern cars, the standard ignition coil has been replaced with a coil for each cylinder of the engine. The ignition coils are found on top of each spark plug but they work the same way as the original coil in that they converted low-voltage current to the high-voltage needed by the spark plug.

Generally, electronic ignition systems are more reliable and require maintenance less often than older ignition systems.

For the best selection of ignition coils, check out PerTronix Performance Brand coils. It has the largest selection and the most helpful staff.

What Does the Distributor Do?

The distributor is a vital part of the ignition system. Cars have multiple cylinders (e.g., 4-cylinder, 6-cylinder, etc.). Each cylinder needs to receive its spark to ignite the fuel and air mixture at the correct time. The correct time is when the piston, which rotates through a complete 360o circle is just before top dead center on its combustion stroke. It is only at its optimal location for a spark for a tiny fraction of a second. Therefore, timing each spark to occur at the exact right moment in each of the cylinders is critical. This is the job of the distributor.

The distributor also has the vital job of directing the high-voltage electricity from the coils to the correct cylinder at the right time. Therefore, the “timing” must be occasionally adjusted on cars with traditional distributors. In older cars this is done with a distributor timing light, much like a times strobe light. It ensures that the high-voltage electricity will be released into the cylinder at the correct time.

In modern cars, distributors have been replaced in the ignition system with a set of coils sitting directly on top of each spark plug. The car’s computer system dictates precisely when the high voltage electricity will flow through the spark plug to create the spark in the cylinder at the perfect time to maximize the power on the rotating piston. These types of electronic ignition systems without distributors need even less maintenance.

How Do Ignition Points Work?

Ignition points are mechanical devices located in the distributor. Ignition points, also known as breaker points,  are generally found in older vehicles. As the distributor turns, the contact points open and close controlling the flow of electricity through the ignition coil. The magnetic field in the coil will charge and then discharge based on the points opening and closing sending the spark through the coil wire into the distributor where it is sent to the appropriate cylinder by the rotor inside the distributor. 

Most cars built in the mid-1970s and after stopped using ignition points as the electronic ignition system became popular. With electronic ignition systems, which began in 1972, the points in the distributor were eliminated. An electronic pick-up replaced the points eliminating the need for maintenance or replacement.

For more information or to find the right ignition system part for your car, truck, or motorcycle, contact PerTronix Performance Brands today.