AutoZone 2012 Hyundai Truck Tucson GL 2WD 2.0L MFI DOHC 4cyl | Repair Guides | Driveability & Emissions Controls | Emission Controls | Exhaust Gas Recirculation (egr) System | AutoZone.com

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    Nissan Maxima 1993-1998 Repair Guide

    Exhaust Gas Recirculation (EGR) System

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    OPERATION



    See Figure 1



    Click image to see an enlarged view

    Fig. Fig. 1: Typical EGR function

    The Exhaust Gas Recirculation (EGR) system routes some of the engine exhaust gas back into the engine intake system to reduce emissions. Nissan Maximas use a system that cuts and controls vacuum applied to the EGR valve with an electric solenoid to suit engine operating conditions. This "cut and control" operation is accomplished through the Electronic Control Module (ECM), in conjunction with an EGR and canister control solenoid valve. When the ECM detects any of the following conditions, current flows through the solenoid valve:



    Low engine coolant temperature
     
    Engine starting
     
    High speed engine operation
     
    Engine idling
     
    Excessively high engine coolant temperature
     
    Mass air flow sensor malfunction
     

    Such current flow through the solenoid valve causes port vacuum to be discharged into the atmosphere. The EGR valve and canister remain closed.

    The EGR valve controls the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to throttle valve opening. The vacuum controls the movement of a taper valve connected to the vacuum diaphragm of the EGR valve.

    The EGR and canister control solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the coil in the solenoid valve is energized. A plunger will then move to cut the vacuum signal (from the throttle body to the EGR valve and canister purge valve). When the ECM sends an OFF signal, the vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve and canister.

    The EGR Backpressure Transducer (EGRC-BPT) valve monitors exhaust pressure to activate the diaphragm, controlling throttle body vacuum applied to the EGR valve. In this way, the recirculated exhaust gas is controlled in response to positioning of the EGR valve or to engine operation.

    A negative temperature coefficient EGR temperature sensor is used to control EGR operation timing during warm-up and under conditions when the engine temperature is out of normal range.

    SYSTEM TESTING



    1. Start the engine and allow it to reach operating temperature.
    2.  
    3. Check for EGR valve movement while racing the engine from 2000-4000 rpm under no load.
    4.  
    5. The EGR valve diaphragm should lift up and down without restriction.
    6.  
    7. If the EGR valve does not respond as specified, perform component testing.
    8.  

    COMPONENT TESTING



    EGR Valve

    See Figures 2 and 3



    Click image to see an enlarged view

    Fig. Fig. 2: To test the EGR valve, apply vacuum to the valve diaphragm ...



    Click image to see an enlarged view

    Fig. Fig. 3: ... then quickly pull it away and listen for the valve closing

    1. Disconnect the EGR valve vacuum hose.
    2.  
    3. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.
    4.  
    5. The EGR valve diaphragm should lift up. Release the vacuum and the EGR valve diaphragm should lower without restriction.
    6.  
    7. If the EGR valve does not respond as specified, remove the valve and check for obstructions. If no obstructions are found, the EGR valve may be faulty.
    8.  

    EGR Backpressure Transducer (EGRC-BPT) Valve

    See Figure 4



    Click image to see an enlarged view

    Fig. Fig. 4: Cutaway view of the EGRC-BPT valve and operation detail

    1. Label and disconnect the transducer valve's vacuum lines.
    2.  
    3. Plug one of the ports on top of the valve.
    4.  
    5. Blow into the bottom port gently while applying vacuum to the second port on top of the valve. Vacuum should hold steady and not leak.
    6.  
    7. Stop blowing into the bottom port and vacuum should leak out.
    8.  
    9. If the valve does not respond as specified, it may be faulty.
    10.  

    EGR Control Solenoid Valve

    See Figures 5 and 6



    Click image to see an enlarged view

    Fig. Fig. 5: Example of a EGRC control solenoid valve

    1. Label and disconnect the solenoid valve electrical harness and vacuum lines.
    2.  
    3. Apply battery voltage as shown in the illustration (12v DC) to the solenoid terminals.
    4.  



    Click image to see an enlarged view

    Fig. Fig. 6: Checking the EGR control solenoid valve by applying voltage. Be sure to apply voltage as shown

    1. Air should pass through Ports A and B freely.
    2.  
    3. Disconnect the power supply from the solenoid.
    4.  
    5. Air should not pass through Ports A and B freely.
    6.  
    7. If the valve does not respond as specified, it may be faulty.
    8.  
    9. If the valve responds as specified, check and repair the power and ground circuits.
    10.  

    EGR Temperature Sensor

    See Figures 7 and 8



    Click image to see an enlarged view

    Fig. Fig. 7: An example of an EGR temperature sensor

    1. Disconnect the temperature sensor electrical harness and measure the resistance between the sensor terminals.
    2.  
    3. Resistance should be high when the sensor is cold and low when the sensor is hot.
    4.  
    5. Compare the cold and hot EGR temperature sensor resistance measurements with the accompanying chart.
    6.  
    7. If resistance is not within specifications or does not respond smoothly as temperature rises and falls, the sensor may be faulty.
    8.  
    9. If the sensor responds as specified, check and repair the power and ground circuits.
    10.  



    Click image to see an enlarged view

    Fig. Fig. 8: Compare the sensor resistance readings with these values

    REMOVAL & INSTALLATION



    EGR Valve

    See Figures 9, 10 and 11

    The EGR valve is located on the intake manifold.

    1. Disconnect the EGR vacuum lines.
    2.  



    Click image to see an enlarged view

    Fig. Fig. 9: Loosen the exhaust inlet pipe (arrow) before removing the mounting bolts

    1. Loosen the EGR valve attaching nuts, then separate the valve from the intake manifold.
    2.  



    Click image to see an enlarged view

    Fig. Fig. 10: Loosen the nuts securing the EGR valve ...



    Click image to see an enlarged view

    Fig. Fig. 11: ... then remove the EGR from the mounting studs on the intake manifold

    1. Remove and discard the EGR valve gasket.
    2.  

    To install:
    1. Thoroughly clean the gasket mating surfaces on the valve and the intake manifold.
    2.  
    3. Install the EGR valve, along with a new gasket, and tighten the mounting nuts to 12-14 ft. lbs. (16-19 Nm).
    4.  
    5. Connect the EGR vacuum lines.
    6.  

    EGR Backpressure Transducer (EGRC-BPT) Valve

    The EGR backpressure transducer valve is located on the intake manifold.

    1. Label and disconnect the valve's vacuum lines.
    2.  
    3. Loosen the valve attaching bolts, then remove the valve from the mounting bracket.
    4.  

    To install:
    1. Position the valve and tighten the mounting bolts to 12-14 ft. lbs. (16-19 Nm).
    2.  
    3. Connect the valve's vacuum lines.
    4.  

    EGR Control Solenoid Valve

    The EGR and canister control solenoid valve is located on the intake manifold.

    1. Label and disconnect the solenoid valve vacuum lines.
    2.  
    3. Loosen the solenoid valve attaching nut, then separate the valve from the intake manifold.
    4.  

    To install:
    1. Install the solenoid valve and tighten the mounting nut to 12-14 ft. lbs. (16-19 Nm).
    2.  
    3. Connect the solenoid valve vacuum lines.
    4.  

    EGR Temperature Sensor
    1. Partially drain the engine cooling system until the coolant level is below the EGR temperature sensor mounting hole.
    2.  
    3. Disconnect the EGR temperature sensor electrical harness.
    4.  
    5. Remove the sensor from the intake manifold.
    6.  

    To install:
    1. Coat the sensor threads with Teflon® sealant.
    2.  
    3. Thread the sensor into the intake manifold and tighten to 11-18 ft. lbs. (15-25 Nm).
    4.  
    5. Connect the negative battery cable.
    6.  
    7. Refill the engine cooling system.
    8.  
    9. Start the engine and check for coolant leaks. Top off the cooling system as necessary.
    10.  

     
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