EMISSION CONTROL SYSTEM GENERAL


  1. OUTLINE


    1. 2 TWCs (Three-Way Catalytic converters) are used in the exhaust system.

    2. The ECM performs the air-fuel ratio feedback control based on signals from the air fuel ratio sensor and the oxygen sensor, and controls the fuel injection amount so that the air-fuel ratio comes close to the stoichiometric air-fuel ratio at which the highest purifying efficiency of CO, HC and NOx is obtained.

    3. An air fuel ratio sensor and an oxygen sensor heater control, which maintain the temperature of the respective sensors at an appropriate level, are used, to improve the detection accuracy of oxygen concentration in exhaust gas.

    4. The EGR control using a high efficiency EGR cooler offers high fuel efficiency and power output. In addition, the E.F.I. vacuum sensor for detecting the intake manifold pressure adjusts the EGR volume to its optimum level.

    5. A blowby gas ventilation system that reduces emissions by forcibly drawing blowby gas which includes a large amount of HC into the air intake side and combusting it again is used.

    6. The evaporative emission control system takes in fuel vapors generated inside the fuel tank into the canister, preventing them from being released into the atmosphere. The ECM controls the purge VSV in accordance with the driving conditions in order to direct the fuel vapors into the engine, where they are burned.