Description and Operation

Description

Exhaust emissions (CO, HC, NOx) are controlled by a combination of engine modifications and the addition of special control components. Modifications to the combustion chamber, intake manifold, camshaft and ignition system form the basic control system. These elements have been integrated into a highly efficient system that controls exhaust emissions while maintaining good drivability and fuel economy. Air-Fuel Ratio Control System [Multi-Point Fuel Injection (MFI) System] The MFI system uses signals from the heated oxygen sensor to activate and control the injector installed in the intake manifold for each cylinder, thereby precisely regulating the air-fuel ratio and reducing emissions. This in turn allows the engine to produce exhaust gas of the proper composition to permit the use of a three-way catalytic converter. The three-way catalytic converter is designed to convert three pollutants [hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx)] into harmless substances. The MFI system has two operating modes.

1. 1
   The air-fuel ratio in open loop is controlled by preprogrammed information in the ECM.
2. 2
   The air-fuel ratio in closed loop is constantly adjusted by the ECM based on information from the oxygen sensor.