How your car works - Electronic Ignition

What is Electronic Ignition?
Most of the cars on today's roads have Electronic Ignition controlling the spark needed to ignite the petrol inside the engine. But when did this technological revolution occur and who noticed it?

Well, it was sometime in the 1970s that some vehicle manufacturers started going over to Electronic Ignition by replacing some of the conventional ignition system components with electronics.

But what was wrong with Contact Breakers?
The problem with conventional ignition systems was that they were prone to wear and to drifting out of adjustment. These conventional systems needed constant attention to keep the engine running efficiently. With an Electronic Ignition system on the other hand, having no moving parts, considerations of wear are virtually done away with, servicing is far less important and reliability is much improved. The system also automatically adjusts to suit all engine conditions and deliver the best possible power and fuel consumption at all times. This means better cold-starting in the morning and cheaper servicing costs.

The technology is now very sophisticated compared to when Electronic Ignition was first introduced. Modern systems will compensate for a whole variety of conditions. For example, the ignition system is now combined with the fuel system to create a communication link from one to another. This is called Engine Management.

By controlling the ignition electronically it is possible for the spark to be 'fired' at a precise time to coincide with the optimal fuel delivery, therefore producing more power and less emissions into the process.

Now there is the keyword! Emissions
This is one of the main justifications for the introduction of Electronic Ignition along with a vast array of other advanced technology within the motor vehicle. A key concern of the motor manufacturers today is to lower the exhaust emission levels into the atmosphere. This has brought about many amazing changes to the design of cars and Electronic Ignition was amongst the first of these innovations to be introduced.

During the 1970s it was possible to buy and fit an Electronic Ignition system to your car as a 'bolt-on' device. These worked quite well, succeeding in increasing the reliability and performance substantially and only really became redundant when the motor manufacturers starting fitting Electronic Ignition as standard.

How does it work?
Low tension circuit: The system works by generating a small electrical current from a sensor within the distributor. This is achieved by using various different types of sensor. Optical, Hall Effect or Magnetic Reluctance are the main ones. The sensor is similar to conventional contact breakers that 'make and break' a circuit to switch the current 'on and off'. The sensor is activated when a rotating 'chopper' plate is passed over it. The sensor can then switch and send the current through to the next stage.

High tension circuit: The small current created by the sensor can be amplified to increase it to a more useable level by the ignition coil. The energy passes through a 'module' that analyses the signal and boosts it ready for the coil. This part of the circuit can be dangerous if handled incorrectly. If you are in any doubt about carrying out repairs to the ignition system then it is best left to your local Unipart Car Care Centre to tackle.

Ignition Coil: This is the part of the system that creates the spark for the spark plugs. It can generate 100,000 volts of electricity and passes it through the spark plugs when it is needed for ignition of the fuel in the engine.

Distributor: The distributor is the part of the system that 'distributes' the high tension voltage to the spark plugs in the engine. A rotor arm spins around inside the distributor cap and carries the energy to each of the High Tension (HT) leads down through to the spark plugs.

Distributorless Ignition: A further development in the Electronic Ignition systems is the distributorless Ignition (DI). Here, the spark is again generated with the help of a coil but instead of one coil for all cylinders each cylinder has it's own dedicated coil. Thus, no distributor is needed. The ECM simply switches on each coil when needed.

What happens if it stops working?
In practice, Electronic Ignition is very reliable but it can break down like anything else electrical. If any part of the system was to fail, it generally results in the whole system shutting down. This of course means that without the vital spark the engine will not run. When the systems fail they usually give very little, if any, warning that they are about to pack up. This can result in inconvenience and frustration as you try to get the problem sorted as cheaply and quickly as possible. Unless you have an in-depth knowledge of automotive electronics and the necessary test equipment then it is best left to the nearest garage to diagnose the problem. It is very difficult to find anything physically broken with any part of the electronic system as it is usually the internal electronic components that fail.

Caring for your Electronic Ignition System: Safety / general warnings

• Avoid any contact with an Electronic Ignition system if you have a Heart Pacemaker fitted. The energy generated from a high voltage system can be sufficient to interfere with the operation of the Pacemaker.
• Avoid touching any part of the system, especially in wet conditions as there is the possibility of electric shock from the system components.
• If you are in any doubt about the system operating correctly (e.g. engine misfiring, excessive fuel economy, etc.) then take your car to a garage for an inspection of the ignition system. It should not take long for the Technician to establish if the system is healthy or not.