EMISSION CONTROL SYSTEM DETAILS


  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.
      Air Fuel Ratio Sensor These sensors detect the oxygen concentration in the exhaust emissions by measuring the electromotive force which is generated in the sensor itself. For details, see the 2UR-FSE Engine Control.
      Oxygen Sensor
      Evaporative Emission Control System ECM Sends signals to the purge VSV to control the purge flow.
      Purge VSV 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.
      Charcoal Canister Assembly Contains activated charcoal to absorb the fuel vapor that is created in the fuel tank.

  2. FUNCTION


    1. The ECM controls the purge flow of evaporative emission (HC) in the charcoal canister assembly in accordance with the engine conditions.

  3. CONSTRUCTION


    1. Three-Way Catalyst (TWC)


      1. A ceramic type TWC is provided in the exhaust manifold sub-assembly and also in the front exhaust pipe assembly.

        A01GUUSE01
        Text in Illustration
        *1 TWC - -

  4. OPERATION


    1. Evaporative Emission Control


      1. Based on the signals from various sensors, the ECM opens and closes the purge VSV. Thus, it controls the purge flow of evaporative emissions (HC) in the charcoal canister subassembly in accordance with the engine conditions.