Ignition Systems Ignition Systems

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Ignition ‘maps’ are what is Ignition ‘maps’ are what is stored inside of an ignition ECU. stored inside of an ignition ECU.

It is a series of factory It is a series of factory programmed settings and are programmed settings and are

not adjustable. not adjustable.

During the design stage of the During the design stage of the engine, manufacturers calculate engine, manufacturers calculate

the optimum ignition timing to the optimum ignition timing to give best results for power, give best results for power,

economy, cold start, over run economy, cold start, over run etc. etc.

Below is a typical graph to show Below is a typical graph to show timing advance with a timing advance with a

mechanical distributor, and mechanical distributor, and below that, a typical engine map below that, a typical engine map to show speed and load timing to show speed and load timing

advance. advance.

Ignition advance with a mechanical Ignition advance with a mechanical distributordistributor

Ignition advance with an ignition Ignition advance with an ignition map map

Compare the advance characteristics Compare the advance characteristics between the two systems. Which gives the between the two systems. Which gives the

best engine performance and why?best engine performance and why?

Compare the two systems shown, Compare the two systems shown, and offer advantages gained by and offer advantages gained by

using an ECU with an engine using an ECU with an engine timing map.timing map.

• More accurate ignition timing throughout a wide range of speed and load conditions

• The engine is much more economical• The engine is more responsive

What does the ignition map replace What does the ignition map replace in a conventional ignition system?in a conventional ignition system?

• The centrifugal and vacuum advance mechanisms.

The latest design in ignition The latest design in ignition systems is a trend called systems is a trend called direct direct

ignitionignition. This is where each . This is where each cylinder has its own coil acting cylinder has its own coil acting

directly onto a spark plug. directly onto a spark plug.

Direct ignition coil packDirect ignition coil pack

Separate Coil

Spark plug

In this system a very high In this system a very high voltage spark can be generated, voltage spark can be generated, the voltage can be in excess of the voltage can be in excess of

………… volts.………… volts.40,000

Questions Questions

1. What is an ignition map?

2. What does the map represent?

3. What does the map replace in a conventional distributor?

4. Name an advantage of using an ignition map.

5. What is the name of the ignition system which uses a coil pack per spark plug?

6. Name an advantage of using this ignition system?.

Answers Answers 1. The map shows the varying amounts of

degrees the ignition timing is adjusted due to different engine loads and speeds.

2. The higher the peaks the more advanced is the timing.

3. The vacuum and speed advance systems.

4. Better performance, better economy, more accurate timing throughout varying conditions.

5. Direct ignition

6. Higher ignition voltage – better running and starting