Log In
Search suggestions

    My Vehicles

    1995 Mazda Truck MPV 4WD 3.0L MFI 6cyl

    My Store

    1720 S RIDGEWOOD A
    (386) 427-1210

    OPEN 'til 9:00 PM today

    Save 20% On Orders Over $100

    Use Code: HOLIDAY20

    See Details

    Get A $25 AutoZone Gift Card

    Use Code: HOLIDAY25

    See Details

    Mitsubishi Galant/Mirage/Diamante 1990-2000

    Evaporative Emission Controls

    Print

    OPERATION





    Click image to see an enlarged view

    Fig. Typical evaporative emission control system schematic



    Click image to see an enlarged view

    Fig. Evaporative emission canister commonly used on most models

    Changes in atmospheric temperature cause fuel tanks to breathe, that is, the air within the tank expands and contracts with outside temperature changes. If an unsealed system was used, when the temperature rises, air would escape through the tank vent tube or the vent in the tank cap. The air which escapes contains gasoline vapors.

    The Evaporative Emission Control System provides a sealed fuel system with the capability to store and condense fuel vapors. When the fuel evaporates in the fuel tank, the vapor passes through the EVAP emission valve, through vent hoses or tubes to a carbon filled evaporative canister. When the engine is operating the vapors are drawn into the intake manifold and burned during combustion.

    A sealed, maintenance free evaporative canister is used. The canister is filled with granules of an activated carbon mixture. Fuel vapors entering the canister are absorbed by the charcoal granules. A vent cap is located on the top of the canister to provide fresh air to the canister when it is being purged. The vent cap opens to provide fresh air into the canister, which circulates through the charcoal, releasing trapped vapors and carrying them to the engine to be burned.

    Fuel tank pressure vents fuel vapors into the canister. They are held in the canister until they can be drawn into the intake manifold. The canister purge valve allows the canister to be purged at a pre-determined time and engine operating conditions.

    Vacuum to the canister is controlled by the canister purge valve. The valve is operated by the PCM. The PCM regulates the valve by switching the ground circuit on and off based on engine operating conditions. When energized, the valve prevents vacuum from reaching the canister. When not energized the valve allows vacuum to purge the vapors from the canister.

    During warm up and for a specified time after hot starts, the PCM energizes (grounds) the valve preventing vacuum from reaching the canister. When the engine temperature reaches the operating level of about 120°F (49°C), the PCM removes the ground from the valve allowing vacuum to flow through the canister and purges vapors through the throttle body. During certain idle conditions, the purge valve may be grounded to control fuel mixture calibrations.

    The fuel tank is sealed with a pressure-vacuum relief filler cap. The relief valve in the cap is a safety feature, preventing excessive pressure or vacuum in the fuel tank. If the cap is malfunctioning, and needs to be replaced, ensure that the replacement is the identical cap to ensure correct system operation.

    OBD-II EVAP System Monitor

    Some models have added system components due to the EVAP system monitor incorporated in the OBD-II engine control system. A pressure sensor is mounted on the fuel tank which measures pressure inside the tank, and a purge flow sensor measures the flow of the gases from the canister into the engine.

    The PCM can store trouble codes for EVAP system performance, a list of the codes is provided later in this section. Normal testing procedures can be used, see EVAP System Component Testing in this Section.

    COMPONENT TESTING



    Purge Control System Check
    1990-93 VEHICLES EXCEPT 1990-92 2.0L DOHC TURBO


    Click image to see an enlarged view

    Fig. To test the purge control operation, connect the vacuum hose from the throttle body to a vacuum pump

    1. Disconnect the red striped vacuum hose from the throttle body and connect it to a hand held vacuum pump.
    2.  
    3. Plug the open nipple on the throttle body.
    4.  
    5. Using the hand pump, apply vacuum while the engine is idling. Check that vacuum is maintained or released as outlined below:
    6.  

    1. With the engine coolant at 140°F (60°C) or less-14.8 in. Hg of vacuum is maintained.
    2.  
    3. With the coolant at 158°F (70°C) or higher-14.8 in. Hg of vacuum is maintained.
    4.  

    1. With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm within 3 minutes of starting vehicle. Try to apply vacuum using the hand held pump. Vacuum should leak.
    2.  
    3. With the engine coolant at 158°F (70°C) or higher, run the engine at 3000 rpm after 3 minutes have elapsed after starting vehicle. Apply 14.8 in. Hg of vacuum. The vacuum should be maintained momentarily, after which it should leak.
    4.  


    NOTE
    The vacuum will leak continuously if the altitude is 7,200 ft. or higher, or the intake air temperature is 122°F (50°C) or higher.

    1. If the test results differ from the desired results, the purge control system is not operating properly.
    2.  

    1990-92 2.0L DOHC TURBO ENGINES
    1. Disconnect the purge air hose from the intake hose and plug the air intake hose.
    2.  
    3. Connect a hand vacuum pump to the purge air hose.
    4.  
    5. Under various engine conditions, inspect the system operation:
    6.  

    1. Allow the engine to cool to a temperature of 140°F (60°C) or below.
    2.  
    3. Start the engine and run at idle.
    4.  
    5. Using the hand pump, apply 14.8 in. Hg of vacuum. In this condition, the vacuum should be maintained.
    6.  
    7. Raise the engine speed to 3000 rpm.
    8.  
    9. Using the hand pump, apply 14.8 in. Hg of vacuum. In this condition, the vacuum should be maintained.
    10.  

    1. Run the engine until the coolant temperature reaches 158°F (70°C). Inspect system operations as follows:
    2.  

    1. Using the hand pump, apply 14.8 in. Hg of vacuum with the engine at idle. In this condition, vacuum should be maintained.
    2.  
    3. Increase the engine speed to 3000 rpm within 3 minutes of starting the engine. Try applying vacuum. The vacuum should leak.
    4.  
    5. After 3 minutes have elapsed after starting engine, raise the engine speed to 3000 rpm. Apply 14.8 in. Hg of vacuum. Vacuum should be maintained momentarily, after which it will leak.
    6.  


    NOTE
    The vacuum will leak continuously if the altitude is 7200 ft. or higher or the air temperature is 122°F (50°C) or higher.

    1. If the results of either test differs from specifications, the system is not functioning properly and will require further diagnosis.
    2.  

    1994-00 VEHICLES

    NOTE
    This test requires the use of a special purge flow indicator tool, MB991700, or equivalent.

    1. Disconnect the purge hose from the EVAP canister, then connect Purge Flow Indicator MB991700, or equivalent between the canister and the purge hose.
    2.  
    3. The engine should be warmed up to operating temperature, 170-203°F. (80-95°C), with all lights, fans and accessories off. The transaxle should be in Park for automatics or Neutral for manuals.
    4.  



    Click image to see an enlarged view

    Fig. Purge control system check-2.4L engine

    1. Run the engine at idle for at least 3-4 minutes.
    2.  
    3. Check the purge flow volume when the brake is depressed suddenly a few times. The reading should be 2.5 SCFH (20cm/sec.)
    4.  
    5. If the volume is less than the standard value, check it again with the vacuum hose disconnected from the canister. If the purge flow volume is less than the standard, check for blockages in the vacuum port and vacuum hose, and also inspect the evaporative emission purge solenoid and purge control valve.
    6.  
    7. If the purge flow volume is at the standard value, replace the EVAP canister.
    8.  

    Purge Control Valve
    1990-93 2.0L TURBO ENGINE
    1. The purge control valve is located to the right side of the battery. Remove the purge control valve from the engine compartment.
    2.  
    3. Connect a hand vacuum pump to the vacuum nipple of the purge control valve.
    4.  



    Click image to see an enlarged view

    Fig. Attach a hand vacuum pump to the nipple on the purge control valve

    1. Apply 15.7 in. Hg of vacuum and check air tightness. Blow in air lightly from the evaporative emission canister side nipple and check conditions as follows:
    2.  
    3. If there is no vacuum applied to the valve-air will not pass.
    4.  
    5. When 8.0 in. Hg of vacuum is applied to the valve-air will pass through.
    6.  
    7. Connect a hand vacuum pump to the positive pressure nipple of the purge control valve.
    8.  
    9. Apply a vacuum of 15.7 in. Hg and check for air tightness. The valve should be air tight.
    10.  
    11. If the results differ from the desired outcomes, replace the purge control valve.
    12.  

    Evaporative Emission Purge Solenoid
    1990-93 VEVICLES EXCEPT 1990-92 2.0L DOHC TURBO
    1. Label and disconnect the 2 vacuum hoses from the purge control solenoid valve.
    2.  
    3. Detach the electrical harness connector from the solenoid.
    4.  
    5. Connect a hand vacuum pump to the nipple which the red striped vacuum hose was connected.
    6.  



    Click image to see an enlarged view

    Fig. Use a hand-held vacuum gauge to check for air-tightness-1990-93 2.0L non-turbo and 1993 2.0L turbo engines

    1. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. The desired results are as follows:
    2.  
    3. With battery voltage applied-vacuum should leak
    4.  
    5. With battery voltage not applied-vacuum should be maintained
    6.  
    7. Measure the resistance across the terminals of the solenoid. The desired reading is 36-44 ohms when at 68°F (20°C).
    8.  



    Click image to see an enlarged view

    Fig. Battery voltage applied to the terminals of the evaporative emission purge solenoid



    Click image to see an enlarged view

    Fig. Measuring the resistance between the terminals of the evaporative emission purge solenoid

    1. If any of the test results differ from the desired outcomes, replace the purge control solenoid.
    2.  

    1990-92 2.0L DOHC TURBO ENGINE
    1. Label and disconnect the 2 vacuum hoses from the purge control solenoid valve.
    2.  
    3. Detach the electrical harness connector from the solenoid.
    4.  
    5. Connect a hand vacuum pump to the nipple which the red striped vacuum hose was connected.
    6.  
    7. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. With battery voltage applied, vacuum should be maintained. Without voltage, vacuum should leak
    8.  
    9. Measure the resistance across the terminals of the solenoid. The desired reading is 36-44 ohms when at 68°F (20°C).
    10.  
    11. If any of the test results differ from the specifications, replace the emission purge control solenoid.
    12.  

    1994-00 VEHICLES
    1. Tag and disconnect the vacuum hoses from the solenoid valve.
    2.  
    3. Detach the harness connector.
    4.  
    5. Attach a hand-held vacuum pump to the nipple (A) of the solenoid valve, as shown in the accompanying figures.
    6.  



    Click image to see an enlarged view

    Fig. Test connections for the evaporative purge solenoid-2.4L engine

    1. Check air tightness by applying a vacuum with voltage applied directly from the battery to the evaporative emission purge solenoid and without applying voltage. The desired results are as follows:
    2.  
    3. With battery voltage applied-vacuum should be maintained
    4.  
    5. With battery voltage not applied-vacuum should leak
    6.  
    7. Measure the resistance across the terminals of the solenoid. The standard values are as follows:
    8.  



    Click image to see an enlarged view

    Fig. Measure the resistance across the terminal of the solenoid valve-2.4L engine shown, others similar

    1. 25-44 ohms when at 68°F (20°C).
    2.  

    1. If any of the test results differ from the specifications, replace the emission purge control solenoid.
    2.  

    REMOVAL & INSTALLATION



    EVAP Canister


    Click image to see an enlarged view

    Fig. Remove the canister retaining bolts and remove the canister

    1. Disconnect the negative battery cable.
    2.  
    3. If necessary, raise and safely support the vehicle, remove the front passenger side wheel, then remove the splash shield.
    4.  
    5. Tag and disconnect all necessary vacuum lines.
    6.  
    7. Unfasten and retaining bolts and/or straps, then remove the canister from the vehicle
    8.  
    9. Installation is the reverse of the removal procedure.
    10.  

    Solenoid Valves


    Click image to see an enlarged view

    Fig. Evaporative emission purge solenoid location-2.0L DOHC engine



    Click image to see an enlarged view

    Fig. Location of the evaporative emission purge solenoid-1990-93 2.0L DOHC turbo engine

    1. Disconnect the negative battery cable.
    2.  
    3. Label and remove the vacuum and electrical harness connections from the purge control solenoid.
    4.  
    5. Remove the solenoid and mounting bracket from the engine compartment.
    6.  
    7. Installation is the reverse of the removal procedure.
    8.  

     
    AutoZone Logo