Ignition System: Description and Operation

Ignition System Diagram:

To produce a spark that will ignite the air/fuel mixture within an engine's cylinders, ignition systems generate high voltage and direct it to spark plugs at each cylinder. Voltage must be high enough to jump the spark plug gap under compression and it must be supplied at the correct time under a wide range of operating conditions. Various systems of controlling spark generation and timing have been devised. These range from completely mechanical to ECU activated electronic to distributorless.

This vehicle utilizes an ECU controlled electronic ignition system. Components include:

1. Ignition coil.
2. Camshaft driven distributor with crank angle sensor.
3. Igniter.
4. Distributor cap and high tension wiring for distributing high voltage to the spark plugs.

The crank angle sensor is a hall effect sensor that provides the ECU with signals regarding engine rpm and #1 cylinder TDC (crankshaft position). Together with other inputs, the ECU calculates ignition timing over the range of vehicle operating conditions.

An ECU controlled igniter is used as a switch to regulate current flow through the coil primary circuit. Each time current flow is interrupted, high voltage is induced in the coil secondary windings to fire the spark plugs. Except for the initial setting, timing is determined by the ECU.

A distributor cap, rotor and high tension wires are used to direct high voltage from the coil to each spark plug at the appropriate time as calculated by the ECU.