Chrysler Concorde/Intrepid/LHS/New Yorker/Vision 1993-1997

Exhaust Gas Recirculation System

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OPERATION



This system reduces the amount of oxides of nitrogen (NO x ) in the exhaust by allowing a predetermined amount of exhaust gases to recirculate and dilute the incoming fuel/air mixture. The diluted air/fuel mixture reduces peak flame temperature during combustion, which in turn inhibits the production of Nitrogen oxides.

The principal components of the system are:



EGR tube (connects a passage in the intake manifold to the exhaust manifold)
 
EGR valve
 
Electronic EGR Transducer
 
Vacuum hoses
 

The electronic EGR transducer contains an electrically operated solenoid and a back-pressure transducer. The Powertrain Control Module (PCM) operates the solenoid. The PCM determines when to energize the solenoid. Exhaust system backpressure controls the transducer.

When the PCM grounds the solenoid, which causes it to energize, vacuum does not reach the transducer. Vacuum flows to the transducer when the PCM de-energizes the solenoid.

When the exhaust system backpressure becomes high enough, it fully closes a bleed valve in the transducer. When the PCM de-energizes the solenoid and backpressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve.

De-energizing the solenoid, but not fully closing the transducer bleed hole (because of low backpressure), varies the strength of vacuum applied to the EGR valve. Varying the strength of the vacuum changes the amount of EGR supplied to the engine. This provides the correct amount of exhaust gas recirculation for different operating conditions.

These systems do not allow EGR at idle. The system does not operate when the engine coolant temperature is below 40°F (5°C) at start-up. These systems activate when the coolant temperature reaches 170°F (77°C).

COMPONENT AND SYSTEM TESTING



EGR System
  1. Check the condition of all of the EGR system hoses and tubes for leaks, hardening or kinks on the rubber hoses. Repair and correct these conditions before proceeding any testing.
  2.  
  3. Be sure that the hoses at both of the EGR valve and EGR valve control are connected to the proper fittings.
  4.  
  5. Be sure the electrical connector is firmly attached at the valve control.
  6.  
  7. To check the EGR system operation, connect the DRB III scan tool or equivalent to the 16-way data link connector. The data link connector is located on the lower edge of the instrument panel near the steering column. Follow the scan tool instructions.
  8.  
  9. After checking the system with the DRB III scan tool, proceed to the EGR valve leak and control tests, then repair as necessary.
  10.  

Gas Flow

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Components used in the EGR system

Use the following test to determine if the exhaust gas is flowing through the EGR valve. It can also be used to determine if the EGR tube is clogged, or if the system passages in the intake or exhaust manifolds are clogged. This test is not to be used as a completer test of the EGR system.

  1. Start the engine, and run to complete operating temperature.
  2.  

The engines are equipped with two fittings located on the EGR valve. The upper fitting supplies the engine vacuum to a diaphragm within the EGR valve for valve operation. The lower fitting is used to supply exhaust backpressure to the EGR valve control.

  1. Disconnect the hose at the fitting, located at the top of the EGR valve vacuum motor.
  2.  
  3. Connect a hand held vacuum pump to this fitting.
  4.  
  5. Start the engine.
  6.  
  7. Slowly apply 5 in Hg (1.2 kPa) to the fitting open the EGR valve motor.
  8.  
  9. While applying the vacuum, and with the engine running at idle speed, the idle speed should drop or the engine may even stall.
  10.  
  11. If the engine speed does not change, the EGR valve may be defective, the EGR tube may be clogged, or the intake and exhaust manifolds may be plugged with carbon.
    1. Remove the EGR valve from the engine.
    2.  
    3. Apply vacuum to the vacuum motor fitting and observe the stem on the EGR valve. If the stem is moving, it can be assumed that the EGR is functioning . The problem is in the clogged EGR tube or passages at the intake or exhaust manifolds (proceed to the next step if this is the problem.) If the stem will not move, replace the EGR valve.
    4.  
    5. Remove the EGR tube between the intake and exhaust manifolds. Check and clean the tube and it's related openings on the manifolds.
    6.  

  12.  
  13. Do not attempt to clean the EGR valve. If the valve shows evidence of heavy carbon build-up near the base, replace the EGR valve.
  14.  

EGR Valve Leak Test

See Figure 2



Click image to see an enlarged view

Fig. Fig. 2: Some EGR valves may be tested using a vacuum pump by watching for diaphragm movement

If the engine will not idle, dies out on an idle, or the idle is rough or slow, the poppet valve at the base of the EGR valve may be leaking in the closed position. The engine must be OFF for the following test.

  1. Disconnect the hose from the top fitting of the EGR valve.
  2.  
  3. Connect a hand held vacuum pump to the fitting.
  4.  
  5. Apply 15 in Hg (3.7 kPa) to the pump.
  6.  
  7. Observe the gauge reading on the pump.
  8.  
  9. If the vacuum falls off, the diaphragm in the valve is ruptured. Replace the EGR valve.
  10.  
  11. A small metal fitting (backpressure fitting) is located at the base of the EGR valve. A hose connects it to the backpressure fitting on the EGR valve control. Disconnect the hose at the EGR valve fitting.
  12.  
  13. Remove the air cleaner housing from the throttle body.
  14.  
  15. Using compressed air, and an air nozzle with a rubber tip, apply approximately 50 psi (12 kPa) of regulated air to the metal backpressure fitting on the EGR valve.
  16.  
  17. By hand, open the throttle to the wide open position. The air should not be heard emitting from the intake manifold while applying air pressure at the backpressure fitting.
  18.  
  19. If air can be heard emitting from the intake manifold, the poppet valve is leaking at the bottom of the EGR valve. Replace the EGR valve.
  20.  

EGR Transducer

The first part of the test will determine if the transducer diaphragm at the backpressure side of the valve is ruptured or leaking. The second part of the test will determine if the engine vacuum is flowing from the inlet to the outlet side of the valve. Do not use this as a complete test of the EGR system.

  1. Disconnect the hose from the bottom fitting of the EGR valve.
  2.  
  3. Connect a hand held vacuum pump to the fitting.
  4.  
  5. Apply 10 in Hg (2.4 kPa) to the fitting.
  6.  
  7. If the vacuum falls off, the valve diaphragm is leaking.
  8.  
  9. Replace the EGR valve.
  10.  
  11. Remove the hose at the vacuum inlet fitting on the EGR valve.
  12.  
  13. Connect the vacuum gauge to this disconnected hose.
  14.  
  15. Start the engine and bring to operating temperature. Hold the idle speed to approximately 1500 rpm.
  16.  
  17. Check for steady engine vacuum at this hose.
  18.  
  19. If the engine vacuum is not present, check the vacuum line to the engine and repair if necessary before proceeding.
  20.  
  21. Reconnect the hose to the vacuum inlet fitting on the EGR valve.
  22.  
  23. Disconnect the hose to the outlet fitting on the valve.
  24.  
  25. Connect the vacuum gauge to the outlet fitting.
  26.  
  27. Disconnect the wiring at the valve control. This will simulate a pin circuit at the valve.
  28.  
  29. Start the engine and bring to operating temperature.
  30.  
  31. Hold the idle speed to approximately 2000 rpm while checking the engine vacuum at the outlet fitting.
  32.  
  33. Have a helper monetarily (one or two seconds) hold a rag over the tailpipe opening to build up some backpressure while you observe the gauge.
  34.  


WARNING
Do not cover the tailpipe for long periods of time, this will cause damage to components or overheating may result.

  1. As temporary backpressure is built, full vacuum should be observed at the outlet fitting. Without backpressure, and the engine at 2000 rpm, the gauge reading will be low. This low reading is normal. At idle speed, the reading should be erratic. This is also normal.
  2.  
  3. If full vacuum is not present at the outlet fitting, but was at the inlet fitting, replace the EGR valve.
  4.  

REMOVAL & INSTALLATION



EGR Valve and Transducer
3.3L ENGINE

See Figures 3, 4 and 5

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Fig. Fig. 3: EGR valve and transducer-3.3L engine



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Fig. Fig. 4: If the manifold is off the vehicle, it will be easier to remove the valve-3.3L engine



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Fig. Fig. 5: Always discard the old and install a new gasket for the EGR valve-3.3L engine

  1. Disconnect the transducer solenoid from the vacuum lines on the manifold.
  2.  
  3. Disconnect the wiring from the solenoid.
  4.  
  5. Remove the EGR valve mounting screws.
  6.  
  7. Remove the valve and transducer.
  8.  
  9. Clean both gasket surfaces and check for any signs of leakage or cracks. Replace the components if any such damage is found or if the valve fails the tests.
  10.  

To install:
  1. Install a new gasket and the EGR valve onto the manifold. Install the two attaching bolts and tighten to 16 ft. lbs. (22 Nm).
  2.  
  3. Reconnect the vacuum lines and electrical wires to the electrical EGR transducer.
  4.  

3.5L ENGINE

See Figures 6, 7 and 8

Click image to see an enlarged view

Fig. Fig. 6: EGR valve and transducer assembly-3.5 engine



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Fig. Fig. 7: The EGR valve attaches to the back of the cylinder head-3.5L engine



Click image to see an enlarged view

Fig. Fig. 8: Loosen, but do not remove, the EGR tube to intake manifold screws

The EGR valve attaches to the rear of the right cylinder head.

  1. Remove the vacuum tube from the electric EGR transducer solenoid. Inspect the vacuum lines for cracking, poor seal due to hardness, or other problems. Replace with new hoses if necessary.
  2.  
  3. Remove the electrical connector from the solenoid.
  4.  
  5. Slide the transducer up and out of the mounting bracket.
  6.  
  7. Loosen, but do not remove, the EGR tube to the intake manifold screws.
  8.  
  9. Remove the EGR tube lower screws at the valve.
  10.  
  11. Remove the EGR valve and transducer.
  12.  
  13. Clean both gasket surfaces and check for any signs of leakage or cracks. Replace the components if any such damage is found or if the valve fails the tests.
  14.  

To install:
  1. Loosely install the EGR valve and a new gasket onto the cylinder head.
  2.  
  3. Using a new gasket, attach the EGR tube to the valve and tighten the screws to 95 inch lbs. (11 Nm).
  4.  
  5. Tighten the EGR tube to the intake manifold plenum screws to 16 ft. lbs. (22 Nm).
  6.  
  7. Tighten the EGR valve to the cylinder head screws to 16 ft. lbs. (22 Nm).
  8.  
  9. Reconnect the transducer solenoid to the vacuum fitting on the manifold.
  10.  
  11. Slide the transducer into the bracket.
  12.  
  13. Reconnect the vacuum lines and electrical wires to the EGR transducer.
  14.  

EGR Tube

3.3L ENGINE

See Figures 9 and 10

Click image to see an enlarged view

Fig. Fig. 9: The EGR tube attaches to the intake manifold plenum below the throttle body and the right exhaust manifold-3.3L engine shown



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Fig. Fig. 10: Remove the EGR mounting screws at the intake manifold plenum-3.3L engine

The EGR tube attaches to the intake manifold plenum below the throttle body and the right exhaust manifold.

  1. Remove the EGR tube attaching screws from the intake manifold plenum.
  2.  
  3. Remove the EGR tube mounting screws at the exhaust manifold.
  4.  
  5. Remove the EGR tube.
  6.  
  7. Clean all gasket surfaces. Inspect gasket surfaces for signs of cracking and replace the EGR tube, plenum or manifold if cracking is found. Discard the old gaskets and supply new ones.
  8.  

To install:
  1. Assemble the tube and new gaskets into place, installing the attaching bolts only loosely.
  2.  
  3. Tighten the attaching screws at the intake manifold plenum to 16 ft. lbs. (22 Nm).
  4.  
  5. Tighten the EGR tube to the exhaust manifold screws to 16 ft. lbs. (22 Nm).
  6.  

3.5L ENGINE

See Figures 11 and 12

Click image to see an enlarged view

Fig. Fig. 11: EGR tube used on the 3.5L engine



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Fig. Fig. 12: Be sure to have the insulation snug against the back of the wiring harness when installing the EGR tube-3.5L engine

The EGR tube attaches to both sides of the intake manifold plenum and the EGR valve.

  1. Remove the air cleaner plenum from the rear of the engine.
  2.  
  3. Remove the EGR tube and valve screws.
  4.  
  5. Remove the tube-to-intake plenum screws.
  6.  
  7. Remove the EGR tube. Discard the old gaskets.
  8.  
  9. Clean the gaskets surfaces.
  10.  

To install:
  1. Loosely install the EGR tube to the EGR valve screws. Finger-tighten the EGR tube mounting screws.
  2.  
  3. Tighten the EGR tube to the EGR valve screws to 95 inch lbs. (11 Nm).
  4.  
  5. Tighten the EGR tube to the intake manifold plenum screws to 16 ft. lbs. (22 Nm).
  6.  
  7. Ensure that the insulation on the EGR tube aligns with and contacts the insulation on the vacuum harness at the rear of the engine.
  8.  

 
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