General Operation

OPERATION

As input signals to the engine controller change, the engine controller adjusts its response to the output devices. For example, the engine controller must calculate a different injector pulse width and ignition timing for idle than it does for wide open throttle (WOT). There are several different modes of operation that determine how the engine controller responds to the various input signals.


OPEN AND CLOSED LOOP MODES OF OPERATION

Modes of operation are of two different types. Open Loop and Closed Loop.

- During Open Loop modes, the engine controller receives input signals and responds only according to preset engine controller programming. Input from the oxygen (02) sensor is not monitored during Open Loop modes.

- During Closed Loop modes, the engine controller will monitor the oxygen (02) sensor input. This input indicates to the engine controller whether or not the calculated injector pulse width results in the ideal air-fuel ratio. This is 14.7 parts air to 1 part fuel. By monitoring the exhaust oxygen content through the O2 sensor, the engine controller can fine tune the injector pulse width. This is done to achieve optimum fuel economy combined with low emission engine performance.


MODES OF OPERATION

The Dual-Point Fuel Injection system has the following modes of operation:

- Ignition switch ON
- Engine start-up
- Engine warm-up
- Cruise
- Acceleration
- Deceleration
- Wide Open Throttle
- Ignition switch OFF

The ignition switch on, engine start-up (crank), engine warm-up, acceleration, deceleration and wide open throttle modes are Open Loop modes. The cruise mode, with the engine at operating temperature is a Closed Loop mode.