Ignition Timing Control

Ignition Timing Control

The ECM controls ignition timing depending upon engine speed, manifold pressure, and engine coolant temperature.

The distributor incorporates an ignition coil, ignition control module, rotor arm, and distributor cap as well as the CKP, TDC, and CYP sensors. The ignition system is controlled by the ECM which utilises several of the inputs also used to calculate fuel injector timing/duration.

Ignition timing is determined by inputs from the following:

1. CKP, TDC, CYP, and MAP Sensors
2. Inlet (intake) Air Temperature Sensor
3. Coolant Temperature Sensor
4. Throttle Position Sensor
5. Starting signal and battery voltage

An output is provided by the ECM to the ignition control module in the distributor and, via the distributor cap, to each spark plug.

ECM back-up functions

Fail-safe function

When a fault occurs in a signal from a sensor, the ECM ignores that signal and assumes a pre-programmed value for that sensor which allows the engine to continue to run.

Back-up function

When a fault occurs in the ECM, the fuel injectors are controlled by a back-up circuit independent of the system in order to permit minimal driving.