Toyota Pick-ups/Land Cruiser/4Runner 1989-1996

Exhaust Gas Recirculation (EGR) System

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OPERATION



Oxides of nitrogen can be formed under conditions of high pressure and very high temperature. Reduction of one of these conditions reduces the production of NOx. A reduction of peak combustion temperature is accomplished by recirculating a small amount of exhaust gases into the combustion chamber.

This metering of exhaust gasses must be carefully monitored. Too much at the wrong time causes extremely poor driveability; too little and the emissions can increase dramatically. EGR function is overseen by an EGR modulator which controls the flow of vacuum (and therefore the flow of exhaust gasses), limiting it to times when the presence of exhaust gas will not adversely effect the running of the engine. The 22R and 22R-E use a Bimetal Vacuum Switching Valve (BVSV) to sense the coolant temperature; in this way, EGR function is limited to warm engine operation. All other engines use a Vacuum Solenoid Valve (VSV) connected to the Engine Control Module (ECM). The computer receives many inputs regarding engine status and temperature; when conditions are favorable, the VSV is activated, allowing EGR function.

Additionally, EGR function is controlled by manifold vacuum so that the valve only operates during periods of high-load or high rpm driving. A binding EGR valve (either open or closed) can cause stalling, missing or reduced fuel economy.

SYSTEM TESTING



2RZ-FE and 3RZ-FE Engines

See Figures 1, 2 and 3



Click image to see an enlarged view

Fig. Fig. 1: The filter is directly beneath the cap

  1. Remove the EGR vacuum modulator cap and filter.
  2.  
  3. Check the filter for damage or contamination.
  4.  
  5. With compressed air, clean the filter.
  6.  
  7. Reinstall the filter and cap. Install the filter with the coarser surface facing the atmospheric side (outwards).
  8.  
  9. Using a 3-way connector, attach a vacuum gauge to the hose between the EGR valve and the EGR vacuum modulator.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: Install a vacuum gauge to the hose between the EGR valve and vacuum modulator

  1. Start the engine and check that the engine starts and runs at idle.
  2.  

The engine coolant temperature should be below 122°F (20°C).

  1. Check that the vacuum gauge indicates zero at 3000 rpm.
  2.  
  3. Check that the EGR pipe is not hot.
  4.  
  5. Remove the 3-way connector with the vacuum hose.
  6.  
  7. Connect the vacuum hose from port Q of the EGR modulator to the EGR valve.
  8.  
  9. Plug the hose from the VSV to the EGR.
  10.  
  11. Remove the vacuum gauge, then reconnect the vacuum hoses to their proper locations.
  12.  
  13. Apply vacuum directly to the EGR valve with the engine at idle.
  14.  



Click image to see an enlarged view

Fig. Fig. 3: Apply vacuum directly to the EGR valve while the engine is idling

  1. Check that the engine now idles rough or stalls.
  2.  
  3. Reconnect the vacuum hoses to their proper locations.
  4.  

1FZ-FE Engines

  1. Check the filter in the EGR modulator for contamination and clean using compressed air.
  2.  
  3. Using a 3-way connector, connect a vacuum gauge inline between the valve and vacuum pipe.
  4.  

Check that the engine starts and idles smoothly.

For accurate system testing, the coolant temperature should be below 117°F (47°C).

  1. Accelerate the engine to 2500 rpm and verify that the vacuum gauge reads 0 in. Hg.
  2.  
  3. Check that the EGR pipe is not hot.
  4.  

For accurate test results, the engine coolant temperature must now be above 127°F (53°C)

  1. Check that the vacuum gauge reads low vacuum at 2500 rpm.
  2.  
  3. Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold.
  4.  
  5. Check that the vacuum reading is high at 2500 rpm. As large amounts of vacuum enters the engine, the engine idle quality may be adversely affected.
  6.  
  7. Remove the vacuum gauge and reconnect the vacuum hoses in their original locations.
  8.  
  9. Apply vacuum directly to the EGR valve with the engine at idle.
  10.  
  11. If the EGR valve is operating properly, the engine should misfire, run rough and possibly stall. Reconnect the vacuum hoses in their proper locations.
  12.  

22R-E and 3VZ-E Engines

  1. Check the filter in the EGR modulator for contamination and clean using compressed air.
  2.  
  3. Using a 3-way connector, connect a vacuum gauge inline between the valve and vacuum pipe.
  4.  
  5. Check that the engine starts and idles smoothly.
  6.  

For accurate system testing, the coolant temperature should be below 118°F (48°C) on 3VZ-E engines or below 93°F (34°C) on 22R-E engines.

  1. Accelerate the engine to 3500 rpm and verify that the vacuum gauge reads 0.
  2.  

For accurate test results, the engine coolant temperature must be above 126°F (52°C) on 3VZ-E engines or above 104°F (40°C) on 22R-E engines.

  1. Check that the vacuum gauge reads low vacuum at 3500 rpm.
  2.  
  3. Disconnect the vacuum hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold.
  4.  
  5. Check that the vacuum reading is high at 3000 rpm. As large amounts of vacuum enters the engine, the engine idle quality may be adversely affected.
  6.  
  7. Remove the vacuum gauge and reconnect the vacuum hoses in their original locations.
  8.  
  9. Apply vacuum directly to the EGR valve with the engine at idle. If the EGR valve is operating properly, the engine should run rough or possibly stall.
  10.  
  11. Reconnect the vacuum hoses in their proper locations.
  12.  

5VZ-FE Engine

See Figures 4 and 5

  1. Remove the EGR vacuum modulator cap and filter.
  2.  
  3. Check the filter for damage or contamination.
  4.  
  5. With compressed air, clean the filter.
  6.  
  7. Reinstall the filter and cap. Install the filter with the coarser surface facing the atmospheric side (outwards).
  8.  
  9. Using a 3-way connector, attach a vacuum gauge to the hose between the EGR valve and the VSV.
  10.  
  11. Start the engine and check that the engine starts and runs at idle.
  12.  
  13. Using the SST 09843-18020 or an equivalent jumper wire, connect terminals TE1 and E1 of the DLC1 under the hood.
  14.  



Click image to see an enlarged view

Fig. Fig. 4: The TE1 and E1 connections are located in the DLC1

The engine coolant temperature should be below 113°F (45°C).

  1. Check that the vacuum gauge indicates zero at 2800 rpm.
  2.  
  3. Check that the EGR pipe is not hot.
  4.  



Click image to see an enlarged view

Fig. Fig. 5: Connect the vacuum gauge as shown

Allow the engine to run until the coolant temperature is above 176°F (80°C).

  1. Check that the vacuum hose gauge reads low vacuum at 2800 rpm.
  2.  
  3. Disconnect the hose from port R of the EGR vacuum modulator and connect port R directly to the intake manifold with another hose.
  4.  
  5. Check the vacuum gauge, it should read high vacuum at 3500 rpm.
  6.  
  7. Disconnect terminals TE1 and E1 by removing the jumper wire.
  8.  
  9. Remove the vacuum gauge, and reconnect the vacuum hoses to their proper locations.
  10.  
  11. Apply vacuum directly to the EGR valve with the engine at idle.
  12.  
  13. Check that the engine idles rough or stalls.
  14.  

REMOVAL & INSTALLATION



EGR Valve

See Figures 6 and 7

  1. Disconnect the EGR pipe, discard of the gasket.
  2.  



Click image to see an enlarged view

Fig. Fig. 6: Detach the EGR pipe from the valve and mounting points on the engine

  1. Label and disconnect the vacuum hoses, EGR hose, water bypass hoses from the IAC valve and water bypass pipe.
  2.  
  3. Some models have an EGR sensor, remove the screws attaching this if applicable.
  4.  
  5. Remove the 2 nuts holding the valve to the engine. Discard the old gasket.
  6.  



Click image to see an enlarged view

Fig. Fig. 7: Remove the two mounting nuts retaining the valve to the engine

  1. Inspect the valve for sticking and heavy carbon deposits.
  2.  

To install:
  1. With a new gasket, mount the valve to the engine. Tighten the mounting nuts to 14 ft. lbs. (19 Nm).
  2.  
  3. Install the EGR sensor if removed.
  4.  
  5. Attach the EGR pipe with a new gasket.
  6.  
  7. Attach the labeled hoses to their proper locations.
  8.  
  9. Start the vehicle and check for any leaks.
  10.  

EGR Vacuum Modulator

  1. Label and disconnect the hoses attached to the modulator.
  2.  
  3. Loosen and remove the nut holding the tube from the modulator to the EGR valve.
  4.  
  5. Remove the modulator.
  6.  
  7. Check the hoses for signs of deterioration and replace as necessary.
  8.  

To install:
  1. Install the modulator and tighten the nut securely.
  2.  
  3. Connect the vacuum hoses.
  4.  

Vacuum Switching Valve (VSV)EXCEPT 1FZ-FE ENGINE

  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the VSV electrical connector.
  4.  
  5. Label and remove the vacuum hoses.
  6.  
  7. Remove the VSV. Installation is the reverse of the removal procedure. During installation, check the vacuum hoses for deterioration and replace as necessary.
  8.  

1FZ-FE ENGINE
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air intake chamber as follows:
    1. Drain the engine coolant. Disconnect the cruise control cable, accelerator cable and the throttle cable at the throttle body.
    2.  
    3. Disconnect the vacuum hoses and the EGR gas temperature sensor connector at the EGR valve.
    4.  
    5. Loosen the EGR pipe union nut. Remove the 2 nuts holding the EGR valve and air intake chamber.
    6.  
    7. Remove the 2 stud bolts, EGR valve and vacuum modulator assembly.
    8.  
    9. Remove the bolt holding the heater pipe and the air intake chamber. Disconnect the air cleaner hose, if still attached.
    10.  

  4.  
  5. Label and disconnect the PCV hoses. Label and disconnect the remaining vacuum hoses. Disconnect the brake booster hose.
  6.  
  7. Disconnect the water bypass hose and the EVAP hose. Unsecure the connector from the emission control valve set assembly, throttle position sensor and the Idle Air Control (IAC) valve.
  8.  
  9. Remove the power steering reservoir tank mounting bolts and position tank aside. Disconnect the fluid lines should not be necessary.
  10.  
  11. Remove the engine oil dipstick and guide. Remove the O-ring from the end of the dipstick guide.
  12.  
  13. Disconnect the engine ground strap.
  14.  
  15. Remove the air intake chamber nuts and bolts and 2 gaskets.
  16.  
  17. Disconnect the vacuum hoses from the the air intake chamber.
  18.  
  19. Remove the 4 mounting bolts and the emission control valve set assembly.
  20.  
  21. Disconnect the harness and 2 vacuum hoses. Remove the screws securing the VSV.
  22.  

To install:
  1. Install the VSV with the mounting screws.
  2.  
  3. Connect the 2 vacuum hoses and the harness connector to the VSV.
  4.  
  5. Install the emission control valve set with the 4 mounting bolts and tighten to 14 ft. lbs. (20 Nm).
  6.  
  7. Connect the vacuum hoses to the air intake chamber.
  8.  
  9. Reinstall the air intake chamber as follows:
    1. Clean the old gasket material from all mating surfaces. Install 2 new gaskets and the air intake chamber with the mounting nuts and bolts. Torque fasteners to 14 ft. lbs. (21 Nm).
    2.  

  10.  
  11. Connect the heater bypass hoses. Connect the engine ground strap.
  12.  
  13. Install new O-ring to the bottom of the oil dipstick guide and lubricate lightly with clean engine oil. Install the guide into the hole in the oil pan and tighten the retainer bolts to 14 ft. lbs. (20 Nm).
  14.  
  15. Install the power steering reservoir in position and secure in place. Tighten the mounting bolts to 13 ft. lbs. (18 Nm).
  16.  
  17. Connect the harness connectors to the emission control valve set assembly, throttle position sensor and IAC valve.
  18.  
  19. Connect the vacuum hoses and the water bypass hoses. Install the air cleaner hose.
  20.  
  21. Install the bolt holding the heater inlet and intake chamber, tightening to 14 ft. lbs. (20 Nm).
  22.  
  23. Install a new gasket, EGR valve and vacuum modulator assembly with the mounting bolts. Tighten bolts to 8 ft. lbs. (10 Nm). Install the 2 nuts holding the EGR valve and air intake chamber and tighten to 14 ft. lbs. (19 Nm).
  24.  
  25. Tighten the union nut of the EGR pipe to 47 ft. lbs. (64 Nm). Connect the EGR gas temperature sensor connector a 3 vacuum hoses to the EGR valve.
  26.  
  27. Connect the throttle cable, accelerator cable and cruise control actuator cable to the throttle body.
  28.  
  29. Fill the cooling system and inspect for leaks.
  30.  
  31. Connect the negative battery cable.
  32.  

EGR Gas Temperature Sensor

  1. Disconnect the negative battery cable. Remove the vacuum modulator.
  2.  
  3. Disconnect the sensor electrical harness.
  4.  
  5. Unscrew the sensor to the EGR valve.
  6.  

To install:
  1. When installing the sensor, coat the threads with anti-seize compound.
  2.  
  3. Tighten the unit to 14 ft. lbs. (20 Nm).
  4.  
  5. Engage the electrical connections.
  6.  

Bimetal Vacuum Switching Valve (BVSV)

  1. Drain the engine cooling system.
  2.  
  3. Unplug and label the vacuum hoses from the valve.
  4.  
  5. Remove the valve using an appropriate sized wrench.
  6.  

To install:
  1. Apply liquid sealer to the bottom threads and install the valve. Tighten the valve to 18 ft. lbs. (25 Nm).
  2.  
  3. Connect the vacuum hoses and refill the engine cooling system.
  4.  

 
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