Toyota Pick-ups, Land Cruiser, and 4 Runner 1997-00

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 gas must be carefully monitored. Too much at the wrong time causes extremely poor drivability; 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. Engines using a Vacuum Solenoid Valve (VSV) have that valve 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.

The 2UZ-FE V8 engine does not use an EGR system.

SYSTEM TESTING



2RZ-FE and 3RZ-FE Engines
  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.  



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Fig. The EGR vacuum modulator filter is directly beneath the cap2RZ-FE and 3RZ-FE engines



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Fig. Install a vacuum gauge to the hose between the EGR valve and vacuum modulator2RZ-FE and 3RZ-FE engines

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

The engine coolant temperature should be below 122° F (50° C).

  1. Check that the vacuum gauge indicates zero at 3,000 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, and then reconnect the vacuum hoses to their proper locations.
  12.  
  13. Apply vacuum directly to the EGR valve with the engine at idle.
  14.  



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Fig. Apply vacuum directly to the EGR valve while the engine is idling2RZ-FE and 3RZ-FE engines

  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. Check that the engine starts and idles smoothly.
  4.  

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

  1. Accelerate the engine to 2,500 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 2,500 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 2,500 rpm. As vacuum builds up and 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.  

5VZ-FE Engine
  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 0984318020 or an equivalent jumper wire, connect terminals TE1 and E1 of the DLC1 under the hood.
  14.  



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Fig. The TE1 and E1 connections are located in the DLC1 connector5VZ-FE engine



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Fig. Connect the vacuum gauge as shown5VZ-FE engine

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

  1. Check that the vacuum gauge indicates zero at 2,800 rpm.
  2.  
  3. Check that the EGR pipe is not hot.
  4.  

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 2,800 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 3,500 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
  1. Disconnect the EGR pipe, discard the gasket.
  2.  
  3. Label and disconnect the vacuum hoses, EGR hose, water bypass hoses from the IAC valve and water bypass pipe.
  4.  
  5. Some models have an EGR sensor, remove the screws attaching this if applicable.
  6.  
  7. Remove the two nuts holding the valve to the engine. Discard the old gasket.
  8.  



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



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Fig. 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.  

 
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