Mitsubishi Car 1999-05

Exhaust Gas Recirculation (EGR) System Repair Guide

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Description & Operation





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Fig. Typical EGR system schematic-2.4L engine shown, others similar

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 ).

The amount of exhaust gas that is reintroduced into the combustion cycle is determined by several factors, such as: engine speed, engine vacuum, exhaust system backpressure, coolant temperature, throttle position. All EGR valves are vacuum operated. The EGR vacuum diagram for your particular vehicle is displayed on the Vehicle Emission Control Information (VECI) label.

Removal & Installation



EGR Solenoid


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Fig. Location of the EGR solenoid-2.4L Galant shown



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Fig. Release the retaining tab and remove the solenoid from the retaining bracket



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Fig. Matchmark the hoses on the solenoid . . .



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Fig. . . . then disconnect the hoses from the solenoid



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Fig. Detach the electrical connector and remove the solenoid from the vehicle

  1. Disconnect the negative battery cable.
  2.  
  3. Label and disconnect the vacuum hoses from the EGR solenoid.
  4.  
  5. Disconnect the electrical harness from the solenoid.
  6.  
  7. Remove the solenoid from the mounting bracket and replace as required.
  8.  

To install:

  1. Install the solenoid to the mounting bracket and secure in position.
  2.  
  3. Attach the electrical connector.
  4.  
  5. Connect the vacuum hoses to the solenoid making sure they are installed in their original location.
  6.  
  7. Connect the negative battery cable.
  8.  

EGR Temperature Sensor
  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the sensor.
  4.  
  5. Remove the sensor from the engine.
  6.  

To install:

  1. Install the sensor to the engine and tighten to 8 ft. lbs. (12 Nm).
  2.  
  3. Attach the electrical connector to the sensor.
  4.  
  5. Connect the negative battery cable.
  6.  

EGR Valve


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Fig. The EGR valve is retained to the intake manifold with two bolts-2.4L engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner and intake hoses as required.
  4.  
  5. If necessary, detach the EGR temperature sensor connector.
  6.  
  7. Tag and disconnect the vacuum hose from the EGR valve.
  8.  
  9. Remove the mounting bolts and the EGR valve from the engine.
  10.  
  11. Clean the mating surfaces on the valve and the engine. Make sure to remove all gasket material.
  12.  
  13. Inspect the valve for a sticking plunger, caused by excess carbon deposits. If such a condition exists, clean with appropriate solvent so valve seats correctly.
  14.  

To install:

  1. Install EGR valve with a new gasket in place.
  2.  
  3. Install the mounting bolts and tighten as follows:
  4.  


    1.5L, 1.6L, and 1.8L engines-7-10 ft. lbs. (10-15 Nm)
     
    2.0L engines-10-15 ft. lbs. (15-22 Nm)
     
    2.4L and 3.5L engines-16 ft. lbs. (22 Nm)
     
    3.0L engines-8 ft. lbs. (11 Nm)
     

  5. Connect the vacuum hose to the EGR valve.
  6.  
  7. If detached, attach the EGR temperature sensor.
  8.  
  9. Install the air cleaner and air intake hoses as required.
  10.  
  11. Connect the negative battery cable.
  12.  

Thermal Vacuum Valve (TVV)
  1. Disconnect the negative battery cable.
  2.  
  3. Detach the vacuum line from the thermo valve.
  4.  
  5. Using a wrench, remove the valve from the engine.
  6.  


NOTE
When removing or installing the valve, do not allow wrenches or other tool to contact the resin part of the valve. Damage to the valve may occur.

  1. Inspect the vacuum hose for cracks and replace as required.
  2.  

To install:

  1. Apply sealant to the threads of the thermo valve and install into the engine.
  2.  
  3. Tighten the valve to 15-30 ft. lbs. (20-40 Nm). When installing the valve, do not allow the wrench to come in contact with the resin part of the valve.
  4.  
  5. Attach the vacuum hose to the valve.
  6.  
  7. Connect the negative battery cable.
  8.  

Testing



EGR Port Vacuum Check
  1. Disconnect the vacuum hose from the throttle body EGR vacuum nipple. Connect a hand-held vacuum pump to the nipple.
  2.  



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Fig. Location of the throttle body EGR valve vacuum nipple-2.4L engine shown

  1. Start the engine, then slowly raise the speed and compare with the following specifications.
  2.  

  1. For 1990-93 vehicles, check to be sure the vacuum raised proportionally with the rise in engine speed.
  2.  
  3. For 1994-00 vehicles, the vacuum reading on the pump should remain constant.
  4.  

EGR Solenoid

NOTE
Before disconnecting the vacuum hoses, tag them to assure proper connection during installation

  1. Tag and disconnect the vacuum hose (2.0L turbo engine: yellow stripe, white and green stripe, 2.4L engine: yellow stripe and white stripe) from the solenoid valve.
  2.  
  3. Detach the harness connector.
  4.  
  5. Connect a hand-held vacuum pump to the A nipple.
  6.  
  7. Check air tightness by applying vacuum with voltage applied directly from the battery to the EGR control solenoid valve and without applying voltage.
  8.  



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Fig. EGR solenoid check connections-2.4L engine

  1. For the 2.4L engines, compare with the following:
  2.  

  1. With battery voltage not applied, vacuum should be maintained.
  2.  
  3. With battery voltage applied, vacuum should leak.
  4.  

  1. Using an ohmmeter, measure the resistance between the solenoid valve terminals. The resistance should fall between 36-44 ohms when the engine temperature is 68°F (20°C).
  2.  

EGR Temperature Sensor

The EGR temperature sensor is used on California vehicles only. The EGR temperature sensor detects the temperature of the gas passing through the EGR control valve. It converts the detected temperature into an electrical voltage signal which is sent the vehicle's Powertrain Control Module (PCM). If the circuit of the EGR temperature sensor is broken, the warning light will come on.

  1. Remove the EGR temperature sensor from the engine.
  2.  



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Fig. Put the EGR temperature sensor in a container of water, then measure resistance as the water temperature is increased

  1. Place the EGR sensor into water. While increasing the temperature of the water, measure the sensor resistance. Compare the values to following specifications:
  2.  

  1. 122°F (50°C)-60-83 kohms resistance
  2.  
  3. 212°F (100°C)-11-14 kohms resistance
  4.  

  1. If the resistance obtained varies significantly from specifications, replace the sensor.
  2.  

EGR Valve
  1. Remove the EGR valve from the vehicle. Check for sticking of plunger caused by excess carbon deposits. If such a condition exists, clean with appropriate solvent so the valve seats correctly.
  2.  
  3. Connect a vacuum pump to the valve and apply 20 in. Hg (67 kPa) of vacuum.
  4.  
  5. Check for air tightness. If the valve has 2 vacuum ports; pick one and plug the other. The vacuum must be retained.
  6.  
  7. For 1990-93 vehicles, blow air from 1 passage of the EGR to check condition as follows:
  8.  
    1. With 1.8 in. Hg (6 kPa) of vacuum or less applied to the valve, air should not pass through the valve.
    2.  
    3. With 8.5 in. Hg (28.7 kPa) of vacuum or more applied to the valve, air should pass through the valve.
    4.  


  1. With 1.8 in. Hg (6 kPa) of vacuum or less applied to the valve, air should not pass through the valve.
  2.  
  3. With 8.5 in. Hg (28.7 kPa) of vacuum or more applied to the valve, air should pass through the valve.
  4.  



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Fig. Use a vacuum pump to test the EGR

  1. For 1994-00 vehicles, apply vacuum (specified below) and check the passage of air by blowing through either side of the EGR passages, as follows:
  2.  

  1. With 1.6 in. Hg or less of vacuum applied to the valve, air should blow out of the opposite passage.
  2.  
  3. With 8.7 in. Hg or more of vacuum applies to the valve, air should not blow out of the opposite passage.
  4.  

  1. If the results are not as described, replace the EGR valve.
  2.  

Thermal Vacuum Valve (TVV)
  1. Label and disconnect the vacuum hose at the thermo valve.
  2.  
  3. Connect a hand held vacuum pump to the vacuum hose on the thermo valve.
  4.  



Click image to see an enlarged view

Fig. Testing the thermal vacuum valve-2.0L engine (Federal) shown, others similar

  1. Apply vacuum and check the air passage through the thermo valve. Compare results to the following specifications:
  2.  

  1. Engine coolant temperature of 122°F (50°C) or less-vacuum leaks
  2.  
  3. Engine coolant temperature of 176°F (80°C) or more-vacuum is maintained
  4.  

  1. If the results differ from the desired specifications, replace the valve.
  2.  

 
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