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    Mercury Villager Nissan Quest 1997-2000

    Exhaust Gas Recirculation System

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    OPERATION

    The exhaust gas recirculation (EGR) system is designed to reintroduce exhaust gas into the combustion chambers, thereby lowering combustion temperatures and reducing the formation of oxides of nitrogen (NO x ). Ported vacuum, applied through the EGR control solenoid and the EGR back pressure transducer (EGR-BPT) valve, opens the EGR valve. A portion of the exhaust gases recirculate from the exhaust system, through the EGR valve, into the intake manifold.

    The EGR control solenoid is controlled by the PCM. Input from various sensors is sent to the PCM, which determines if the EGR valve should be open or closed. The PCM then sends a signal to the EGR control solenoid to open or close the EGR valve. The EGR-BPT valve will not allow the EGR valve to open if there is not sufficient exhaust system back pressure.

    The PCM monitors EGR system flow by monitoring signals from the EGR temperature sensor. If the temperature sensor does not indicate proper EGR system operation, a diagnostic trouble code is stored by the PCM.



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    Fig. Location of the EGR valve and related components-1993-98 vehicles



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    Fig. Location of the EGR valve and related components-1999-00 vehicles

    COMPONENT TESTING
    EGR Control Solenoid

    NOTE
    Two jumper wires are required for the following tests. An in-line fuse holder with a 30 amp fuse should be spliced in the jumper wire that will be connected to the positive battery terminal to prevent possible damage to the battery, wiring, and components of the circuit being tested.

    1993-98 vehicles (except for 1998 california emissions)

    On 1996-98 vehicles (except for 1998 California emissions), the EGR control solenoid also controls vacuum to the evaporative emission system.

    1. Remove the EGR control solenoid from the vehicle.
    2.  
    3. Connect the fused jumper wire between the positive battery terminal and one terminal of the control solenoid.
    4.  
    5. Connect the other jumper wire between the negative battery terminal and the other control solenoid terminal.
    6.  
    7. Blow air into port A . There should be free airflow out of port B .
    8.  
    9. Plug port B and blow air into port A . There should be no airflow out of port C .
    10.  
    11. Disconnect the jumper wires.
    12.  
    13. Plug port C and blow air into port A . There should be no airflow out of port B .
    14.  
    15. Blow air into port A . There should be free airflow out of port C .
    16.  
    17. If the solenoid fails any of the preceding tests, replace the solenoid.
    18.  



    Click image to see an enlarged view

    Fig. EGR control solenoid location-1993-98 vehicles



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    Fig. EGR control solenoid port designations-1993-98 vehicles

    1998 california emissions and 1999-00 vehicles
    1. Remove the EGR control solenoid from the vehicle.
    2.  
    3. Connect the fused jumper wire between the positive battery terminal and one terminal of the control solenoid.
    4.  
    5. Connect the other jumper wire between the negative battery terminal and the other control solenoid terminal.
    6.  
    7. Blow air into port A . There should be free airflow out of port B .
    8.  
    9. Plug port B and blow air into port A . There should be no airflow out of port C .
    10.  
    11. Disconnect the jumper wires.
    12.  
    13. Plug port C and blow air into port A . There should be no airflow out of port B .
    14.  
    15. Blow air into port A . There should be free airflow out of port C .
    16.  
    17. If the solenoid fails any of the preceding tests, replace the solenoid.
    18.  



    Click image to see an enlarged view

    Fig. Jumper wire connections for EGR control solenoid testing-1998 California emissions and 1999-00 vehicles

    EGR-BPT Valve
    1. Disconnect the hoses from the EGR-BPT valve.
    2.  
    3. Connect a hand vacuum pump to the intake manifold vacuum port ( B ).
    4.  
    5. Apply vacuum to the port. If vacuum holds, the valve is not venting and must be replaced.
    6.  
    7. Connect a vacuum gauge to the EGR valve port ( C ).
    8.  
    9. While applying vacuum to the intake manifold vacuum port ( B ), blow air into the exhaust pressure port ( A ). The vacuum gauge should indicate vacuum. If not, replace the valve.
    10.  



    Click image to see an enlarged view

    Fig. EGR-BPT valve location



    Click image to see an enlarged view

    Fig. EGR-BPT valve port designations

    EGR Valve
    1. Start and run the engine until it is at normal operating temperature.
    2.  
    3. Turn the engine OFF .
    4.  
    5. Disconnect and plug the EGR valve vacuum hose.
    6.  
    7. Connect a hand vacuum pump to the EGR valve.
    8.  
    9. Start the engine and allow it to idle.
    10.  
    11. Apply 4.72 in. Hg (120mm Hg) of vacuum to the EGR valve. The engine idle should be unaffected.
    12.  
    13. Apply 4.8-5.0 in. Hg (121.9-127.0mm Hg) of vacuum. The engine should begin to idle roughly.
    14.  
    15. Increase the vacuum further and the engine should stall.
    16.  
    17. If the engine idle is unaffected by applying vacuum over 4.72 in. Hg (120mm Hg), continue by checking the EGR valve diaphragm as follows:
    18.  
      1. Turn the engine OFF and allow it to cool.
      2.  



    CAUTION
    Do not touch the EGR valve while the engine is hot.

    1. While applying vacuum, feel the EGR valve diaphragm. If the diaphragm does not move, replace the EGR valve.
    2.  

    1. If the EGR valve diaphragm is moving properly, but the engine idle is not affected by the preceding tests, remove the EGR valve. Inspect the EGR valve, EGR valve-to-exhaust manifold tube, and intake manifold EGR passages for blockage and clean them, as needed.
    2.  



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    Fig. Disconnecting the EGR valve vacuum hose



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    Fig. The EGR valve may be tested by using a vacuum pump and observing diaphragm movement



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    Fig. Check for EGR valve diaphragm movement while applying vacuum

    EGR Temperature Sensor
    1. With the ignition switch OFF , disconnect the EGR temperature sensor electrical connector.
    2.  
    3. Start and run the engine until it is at normal operating temperature.
    4.  
    5. Turn the engine OFF .
    6.  
    7. Connect ohmmeter leads between the temperature sensor connector terminals. Verify that the meter is set to display megohms.
    8.  
    9. As the engine cools, observe the resistance of the sensor. Compare the resistances with those listed in the chart. If the resistances are outside of specifications, replace the sensor.
    10.  



    Click image to see an enlarged view

    Fig. Check the EGR temperature sensor resistance as the engine cools

    REMOVAL & INSTALLATION
    EGR Control Solenoid
    1. Disconnect the negative battery cable.
    2.  
    3. Disconnect the solenoid electrical connector.
    4.  
    5. Label and remove the vacuum hoses from the solenoid.
    6.  
    7. Remove the nut that attaches the solenoid to the bracket and remove the solenoid.
    8.  
    9. The installation is the reverse of removal.
    10.  

    EGR-BPT Valve
    1993-98 vehicles
    1. Disconnect the EGR-BPT valve vacuum hoses.
    2.  
    3. Remove the EGR-BPT bracket bolts.
    4.  
    5. Remove the EGR-BPT valve and bracket assembly from the vehicle.
    6.  
    7. Remove the two EGR-BPT valve-to-bracket bolts and remove the bracket from the valve.
    8.  
    9. The installation is the reverse of removal.
    10.  

    1999-00 vehicles
    1. Disconnect the three EGR-BPT valve vacuum hoses.
    2.  
    3. Remove the two EGR-BPT valve-to-bracket bolts and remove the valve.
    4.  
    5. The installation is the reverse of removal.
    6.  

    EGR Valve
    1. Disconnect the negative battery cable.
    2.  
    3. Disconnect the vacuum hose from the EGR valve.
    4.  
    5. On 1993-98 vehicles, disconnect the EGR temperature sensor electrical connector.
    6.  
    7. Disconnect the EGR valve-to-exhaust manifold tube from the back of the EGR valve.
    8.  
    9. Disconnect the EGR-BPT valve tube from the EGR valve.
    10.  
    11. Remove the two EGR valve nuts.
    12.  
    13. Remove the EGR valve and discard the gasket.
    14.  

    To install:

    1. Clean the intake manifold mating surface, and the EGR valve mating surface if the old EGR valve is to be reinstalled. A gasket scraper and solvent may be used, however, be careful not to nick or gouge either surface.
    2.  
    3. Install a new gasket and position the EGR valve on the intake manifold.
    4.  
    5. Install the two EGR valve nuts and tighten them to 9-12 ft. lbs. (13-16 Nm).
    6.  
    7. Install the EGR-BPT valve tube and tighten the flare nut to 80 inch lbs. (9 Nm).
    8.  
    9. Install the EGR valve-to-exhaust manifold tube and tighten the flare nut to 25-33 ft. lbs. (34-44 Nm).
    10.  
    11. On 1993-98 vehicles, connect the EGR temperature sensor electrical connector.
    12.  
    13. Install the EGR valve vacuum hose.
    14.  
    15. Connect the negative battery cable.
    16.  

    EGR Temperature Sensor
    1. Disconnect the negative battery cable.
    2.  
    3. Disconnect the EGR temperature sensor electrical connector.
    4.  
    5. Remove the EGR temperature sensor from the intake manifold.
    6.  
    7. The installation is the reverse of removal.
    8.  

     
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