EMISSION CONTROL SYSTEM(w/ Canister Pump Module)


  1. OUTLINE


    1. Exhaust Emission Control System


      1. Three-Way Catalytic converters (TWCs) are used in order to reduce exhaust emissions.

      2. The ECM controls fuel injection volume based on the signals from the air fuel ratio sensor and heated oxygen sensor, optimizing the exhaust emissions.

    2. Exhaust Gas Recirculation (EGR) Control System


      1. The EGR control system uses a high efficiency EGR cooler to obtain high fuel efficiency.

    3. Blowby Gas Ventilation System


      1. A blowby gas ventilation system which 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.

    4. Evaporative Emission Control System


      1. The evaporative emission control system prevents fuel vapors from being released from the fuel tank assembly when the engine is stopped (and the vehicle is parked).

      2. Hybrid vehicles control the engine and only operate it intermittently, making the operation time of the engine shorter than that of conventional gasoline engine models. Due to the engine being unable to burn the fuel vapors from the fuel tank assembly sufficiently, the fuel vapors that are created exceed the capacity of normal-sized canisters. Therefore, this system releases the fuel vapors from the fuel tank assembly only when the engine is running, and burns them in the engine, in order to comply with the LEVIII*1 and Tier3*2 evaporative emissions regulations.

        *1: California Air Resources Board (CARB)

        *2: Environmental Protection Agency (EPA)

      3. The evaporative emission control system on the hybrid vehicle consists of a fuel vapor-containment system (to prevent fuel vapors from escaping into the atmosphere), purge flow control (to purge fuel vapors), and the EVAP leak check (to check for leaks from the evaporative emission control system).

      4. A canister filter is provided on the fresh air line. This air filter is maintenance-free.

        Function Outline
        Fuel Vapor-containment System

        • When the vehicle is parked (with engine stopped), the system closes the fuel vapor-containment valve (fuel tank solenoid main valve assembly) to seal the fuel tank assembly.

        • For refueling, the system opens the fuel vapor-containment valve (fuel tank solenoid main valve assembly), allowing the fuel vapors to be absorbed by the canister and reducing the pressure in the fuel tank assembly.

        • When the engine is operating, the system controls the fuel vapor-containment valve (fuel tank solenoid main valve assembly) to release the fuel vapors and perform purge flow control.
        Purge Flow Control

        • Opens the purge VSV when the engine is running, allowing the engine vacuum to draw the fuel vapors absorbed by the canister and burn them in the engine.

        • The ECM opens the fuel vapor-containment valve (fuel tank solenoid main valve assembly) when the purge VSV is open and the internal pressure of the fuel tank assembly is high. Thus, the fuel vapors in the fuel tank assembly and the fuel vapors absorbed by the canister are drawn into the engine to be burned.
        EVAP Leak Check

        • When the engine is stopped, the ECM operates the canister pump module to perform a leak check in the evaporative emission control system and check the functions of the parts.

        • Depending on the internal pressure of the fuel tank assembly, the ECM performs 2 types of leak check operations:


          • When the internal pressure of the fuel tank assembly is equal to the atmospheric pressure.

          • When the internal pressure of the fuel tank assembly is higher [3 kPa (0.03 kgf/cm2, 0.44 psi) minimum] or lower [-2 kPa (-0.02 kgf/cm2, -0.29 psi) maximum] than the atmospheric pressure.