Air/Fuel Mixture Ratio Control System

AIR/FUEL MIXTURE RATIO CONTROL SYSTEM (Multiport Fuel Injection (MFI) System)
The MFI system employs the signals from the heated oxygen sensor to activate and control the injector installed in the manifold for each cylinder, precisely regulating the air/fuel mixture ratio and reducing emissions.

This allows the engine to produce exhaust gases of the proper composition to permit the use of a three-way catalyst. The three-way catalyst is designed to convert the three pollutants (1) hydrocarbons (HC), (2) carbon monoxide (CO), and (3) oxides of nitrogen (NOx) into harmless substances. The two operating modes in the MFI system are as follows:

1. Open Loop-air/fuel ratio is controlled by information programmed into the ECM during the manufacturing process.
2. Closed Loop-air/fuel ratio is varied by the ECM based on information supplied by the heated oxygen sensor.



EXHAUST EMISSION SYSTEM [Vehicle with catalytic converter]
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. Additional control devices include an exhaust gas recirculation (EGR) system and a catalytic converter.

These systems have been integrated into highly effective system which controls exhaust emissions while maintaining good driveability and fuel economy.


Components Function Remarks

Crankcase Emission System HC reduction - - -
Positive Crankcase Ventilation (PCV) Valve - - - Variable flow rate type

Evaporative Emission System HC reduction - - -
EVAP Canister - - - - - -
EVAP Canister Purge Solenoid Valve - - - Duty control solenoid valve

Exhaust Emission System - - - - - -
MFI system CO,HC,NOx reduction Heated oxygen sensor feedback type
(air-fuel mixture control device)
Three-way catalytic converter CO,HC,NOx reduction Monolith type
Exhaust gas recirculation system NOx reduction - - -
(2.4 DOHC only)
EGR Valve - - - Single type
Manifold absolute pressure sensor EGR Monitoring Electric pressure type

EVAP: Evaporative Emission