Fuel Control (Fuel Injected Models)

All electronic fuel injected (EFI) models are equipped with an electrically-pulsed injector located in a throttle body unit on the intake manifold. The ECM, responding to inputs from data sensors, constantly adjusts air/fuel mixture to maintain engine performance. The ECM controls the pulse width (injector "on" time) to provide the proper amount of fuel for the specific engine requirement. Increasing the injector pulse width, richens the air/fuel ratio. Decreasing the injector pulse width, leans the air/fuel ratio.

When ECM responds to signals received from oxygen sensor to adjust fuel mixture, the CCC system is in closed loop operation. Under certain operating conditions, the ECM may ignore inputs from the oxygen sensor and use a pre-programmed calibration program to control the engine under that particular operating mode. Operating conditions which cause the ECM to ignore oxygen sensor signals cause the CCC system to operate in open loop mode.