Closed-Loop Control

This system controls air/fuel ratio precisely to the stoichiometric point so that the three way catalyst can minimize all exhaust emissions simultaneously. The system uses the exhaust gas sensor, located in the exhaust manifold, to give an indication of whether air/fuel mixture is leaner or richer than stoichiometric point. The sensor transmits a nonlinear voltage to the E.C.C. control unit. The control unit adjusts the feedback pulse width according to sensor voltage so that mixture ratio will be within the narrow window of the three-way catalyst. This system becomes open during engine warm-up until the sensor reaches operating temperature.