EMISSION CONTROL SYSTEM


  1. FUNCTION OF MAIN COMPONENTS


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

      Destination Package for South Korea
      Component Function
      Canister Contains activated charcoal to absorb the fuel vapor that is created in the fuel tank assembly.
      Fresh Air Line Fresh air goes into the canister and the cleaned drain air goes out into the atmosphere.
      Canister Pump Module Vent Valve Opens and closes the fresh air line in accordance with signals from the ECM.
      Leak Detection Pump and Pump Motor Applies vacuum to the evaporative emission system in accordance with signals from the ECM.
      Canister Pressure Sensor Detects the pressure in the evaporative emission system and sends the signals to the ECM.
      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 canister into the intake manifold. In system monitoring mode, this valve controls the introduction of vacuum into the fuel tank assembly.
      Canister Filter Prevents dust and debris in fresh air from entering the system.
      ECM Controls the canister pump module and the purge VSV, in accordance with the signals from various sensors, in order to achieve a purge volume that suits the driving conditions. In addition, the ECM monitors the system for any leak and stores a DTC if a malfunction is found.
      Except Destination Package for South Korea
      Component Function
      Canister Contains activated charcoal to absorb the fuel vapor that is created in the fuel tank assembly.
      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 canister into the intake manifold.
      ECM Controls the purge VSV in accordance with the signals from various sensors in order to achieve a purge volume that suits the driving conditions.

  2. OPERATING CONDITION


    1. Destination Package for South Korea


      1. The following are the typical conditions necessary to enable an evaporative emission leak check:

        Typical Enabling Conditions

        • 5 hours have elapsed after the engine has been turned off*.

        • Altitude: Below 2400 m (8000 ft.)

        • Battery Voltage: 10.5 V or more

        • Engine Switch: off

        • Engine Coolant Temperature: 4.4 to 35°C (40 to 95°F)

        • Intake Air Temperature: 4.4 to 35°C (40 to 95°F)

        • *: If engine coolant temperature does not drop below 35°C (95°F), this time is extended to 7 hours. Even after that, if the temperature is not less than 35°C (95°F), the time is extended to 9.5 hours.

          Tech Tips

          The canister pump module performs a fuel evaporative emission leak check. This check is done approximately 5 hours after the engine is turned off. A sound may be heard coming from underneath the luggage compartment for several minutes. This does not indicate a malfunction. The pinpoint pressure test procedure is adopted by pressurizing the fresh air line that runs from the canister pump module to the canister filter neck. For details, refer to the Repair Manual.

  3. SYSTEM CONTROL


    1. Destination Package for South Korea


      1. Purge Flow Control


        1. When the engine has reached a predetermined state [closed loop, engine coolant temperature above 80°C (176°F), etc.], stored fuel vapor is purged from the canister whenever the purge VSV is opened by the ECM.

        2. The ECM will change the duty ratio cycle of the purge VSV, thus controlling purge flow volume. Purge flow volume is determined by intake manifold pressure and the duty ratio cycle of the purge VSV. Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained whenever purge vacuum is applied to the canister.

          A01MR12E02
          *1 to Intake Manifold
          *2 Atmosphere
          *3 Canister
          *4 Purge VSV (Open)

      2. Onboard Refueling Vapor Recovery (ORVR)


        1. When the internal pressure of the fuel tank assembly increases during refueling, the fuel vapor enters the canister. The air that has had the fuel vapor removed from it will be discharged through the fresh air line. The vent valve is used to open and close the fresh air line. The valve is always open (even when the engine is stopped) except when the vehicle is in monitoring mode (the valve will remain open as long as the vehicle is not in monitoring mode). If the vehicle is refueled in system monitoring mode, the ECM will recognize the refueling by way of the canister pressure sensor, which will detect the sudden pressure increase in the fuel tank assembly, and the ECM will open the vent valve.

          A01MQTVE02
          *1 Canister
          *2 Purge VSV (Closed)
          *3 Vent Valve

      3. EVAP Leak Check


        1. The EVAP leak check operates in accordance with the following timing chart:

          A01MQZJE07
          Order Operation Description Time
          1) Atmospheric Pressure Measurement The ECM turns the vent valve off (vent) and measures EVAP system pressure to determine the atmospheric pressure. 60 sec.
          2) First Reference Pressure Measurement The leak detection pump creates negative pressure (vacuum), limited by a reference orifice and the pressure is measured. The ECM determines this as the reference pressure. 360 sec.
          3) EVAP Leak Check The leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized pressure is larger than the reference pressure, ECM determines that the EVAP system has a leak. If the EVAP pressure does not stabilize within 15 minutes, the ECM cancels the EVAP monitor. Within 15 min.
          4) Purge VSV Monitor The ECM opens the purge VSV and measures the EVAP pressure increase. If the increase is large, the ECM interprets this as normal. 10 sec.
          5) Second Reference Pressure Measurement The leak detection pump creates negative pressure (vacuum) limited by a reference orifice and the pressure is measured. The ECM determines this as the reference pressure. 60 sec.
          6) Final Check The ECM measures the atmospheric pressure and records the monitor result. -

    2. Except Destination Package for South Korea


      1. Purge Flow Control


        1. When the engine has reached a predetermined state [closed loop, engine coolant temperature above 80°C (176°F), etc.], stored fuel vapor is purged from the canister whenever the purge VSV is opened by the ECM.

        2. The ECM will change the duty ratio cycle of the purge VSV, thus controlling purge flow volume. Purge flow volume is determined by intake manifold pressure and the duty ratio cycle of the purge VSV. Atmospheric pressure is allowed into the canister to ensure that purge flow is constantly maintained whenever purge vacuum is applied to the canister.

          A01MQTIC01
          *1 Throttle Valve *2 Intake Air Surge Tank Assembly
          *3 Purge Port *4 Purge VSV
          *5 ECM *6 Canister
          *7 Fuel Tank Assembly - -
          *a Intake Air *b Duty Signal
          *c Atmosphere Release/Intake - -

  4. OPERATION


    1. Atmospheric Pressure Measurement (Destination Package for South Korea)


      1. When the engine switch is turned off, the purge VSV and the vent valve are turned off. Therefore, atmospheric pressure is introduced into the canister.

      2. The ECM measures the atmospheric pressure using the canister pressure sensor.

      3. If the measured atmospheric pressure is out of range, the ECM actuates the leak detection pump in order to monitor changes in the pressure.

        A01MQW4E01

    2. Reference Pressure Measurement (Destination Package for South Korea)


      1. The purpose of this measurement is to confirm leak detection pump operation, and to provide a baseline measurement value that will be used for comparison in subsequent leak test steps.

      2. The vent valve remains off, atmospheric pressure is introduced into the canister and the ECM actuates the leak detection pump, creating a vacuum in the piping close to the canister pressure sensor.

      3. At this time, the pressure will not decrease below what is referred to as the reference pressure due to the atmospheric pressure that enters the piping close to the pump and sensor through the reference orifice.

      4. The ECM compares its standard and this pressure. If the pressure is within the acceptable range, the ECM stores this pressure as the reference leak pressure.

      5. If the pressure is below the standard, the ECM will determine that the reference orifice is clogged and store DTC P043E in its memory.

      6. If the pressure is above the standard, the ECM will determine that a high flow rate pressure is passing through the reference orifice and store DTCs P043F, P2401 and P2402 in its memory.

        A01MR30E01

    3. EVAP Leak Check (Destination Package for South Korea)


      1. While actuating the leak detection pump, the ECM turns the vent valve on in order to introduce a vacuum into the canister.

      2. When the pressure in the system stabilizes, the ECM compares this pressure and the reference pressure in order to determine if a leak is present.

      3. If the detected pressure is below the reference pressure, the ECM determines that there is no leak.

      4. If the detected pressure is above the reference pressure and near atmospheric pressure, the ECM determines that there is a gross leak (large hole) and stores DTC P0455 in its memory.

      5. If the detected pressure is above the reference pressure, the ECM determines that there is a small leak (minor leak) and stores DTC P0456 in its memory.

        A01MQQ0E01

    4. Purge VSV Monitor (Destination Package for South Korea)


      1. After completing an EVAP leak check, the ECM turns the purge VSV on (open) with the leak detection pump actuated, and introduces the atmospheric pressure from the intake manifold to the canister.

      2. If the pressure change at this time is within the normal range (a pressure change occurs), the ECM determines the condition to be normal.

      3. If the pressure change is out of the normal range (insufficient pressure change occurs), the ECM will stop the purge VSV monitor (purge monitor) and store DTC P0441 in its memory.

        A01MQQFE01

    5. Second Reference Pressure Measurement (Destination Packages for South Korea)


      1. While the ECM operates the leak detection pump, the purge VSV and vent valve are turned off and a second reference pressure measurement is performed.

      2. The ECM compares the measured pressure with the pressure during the EVAP leak check.

      3. If the pressure during the EVAP leak check is less than the second reference pressure measurement, the ECM determines that there is no leak.

      4. If the pressure during the EVAP leak check is above the reference pressure and near atmospheric pressure, the ECM determines that there is a gross leakage (large hole) and stores DTC P0455 in its memory.

      5. If the pressure during the EVAP leak check is above the reference pressure measurement, the ECM determines that there is a small leak and stores DTC P0456 in its memory.

        A01MR05E01