EMISSION CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


    1. The main components of the emission control system are as follows:

      System Component Function
      Exhaust Emission Control System ECM Determines an optimal fuel injection volume based on the signals from various sensors.
      TWC

      Oxidizes CO and HC in the exhaust gas and deoxidizes NOx at the same time, to purify them into CO2, H2O and N2.
      Heated Oxygen Sensor This sensor detects the oxygen concentration in the exhaust emission by measuring the electromotive force which is generated in the sensor itself. For details, see the 1UR-FE ENGINE CONTROL.
      Air Fuel Ratio Sensor
      Exhaust Emission Control System Air Injection System ECM

      • Controls the air injection system in accordance with signals from the crankshaft position sensor, engine coolant temperature sensor, mass air flow meter and air pressure sensor.

      • Receives a failure detection signal from the air injection driver and stores a corresponding DTC in memory.
      Air Pump Assembly Uses a built-in DC motor to supply air to the air switching valve assembly.
      Air Switching Valve Assembly Introduces air that is pumped by the air pump assembly into the exhaust manifold.
      Air Injection Control Driver

      • Activated by the ECM, the air injection control driver actuates the air pump assembly and the air switching valve assembly.

      • Detects an input-output circuit failure at the air injection driver and transmits it to the ECM.
      Exhaust Gas Recirculation (EGR) System ECM Determines the EGR volume in accordance with various sensor signals.
      EGR Valve Controls the EGR volume in accordance with ECM signal.
      Vacuum Sensor Detects the negative pressure of the intake manifold and detects malfunctions in the EGR system.
      EGR Cooler Cools the EGR gas.
      Evaporative Emission Control System ECM Sends signals to the VSV for EVAP to control the purge flow.
      Charcoal Canister Assembly Contains activated charcoal to absorb the fuel vapor that is created in the fuel tank.
      VSV for EVAP Opens in accordance with the signals from the ECM when the system is purging, in order to send the fuel vapor that was absorbed by the charcoal canister assembly into the intake manifold.

  2. SYSTEM CONTROL


    1. The emission control system has the following features:

      System Outline
      EGR Control Based on the signals received from the various sensors, the ECM determines the EGR volume via EGR valve in accordance with the engine condition.
      Air Injection System The ECM controls the air injection time based on the signals from the crankshaft position sensor, engine coolant temperature sensor, mass air flow meter and air pressure sensor.
      Evaporative Emission Control The ECM controls the purge flow of evaporative emission (HC) in the charcoal canister assembly in accordance with the engine conditions.

    2. Operating Condition


      1. Air injection system is operated under the following conditions:

        Engine Coolant Temperature 5°C to 45°C (41°F to 113°F)
        Intake Air Temperature 5°C (41°F) or more