Chrysler Front Wheel Drive Cars 6-CYL 1988-1995 Repair Information

Exhaust Gas Recirculation System

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OPERATION



Except Early Premier and Monaco

See Figures 1, 2 and 3

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 (EET)
 
Vacuum hoses
 

The EET 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.



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Fig. Fig. 1: EGR system-3.0L engines, except Premier and Monaco



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Fig. Fig. 2: EGR system-3.3L and 3.8L engines



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Fig. Fig. 3: EGR tube to the exhaust manifold connection-Premier and Monaco

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 (4.5°C) at start-up. These systems activate when the coolant temperature reaches 170°F (77°C).

Early Premier and Monaco

See Figures 3 through 8

If you are not sure whether your Premier or Monaco is designated as an early or late model, please refer to the model differentiation portion of this section.

The EGR system consists of an EGR valve solenoid, backpressure modulated vacuum transducer, and the EGR valve.

The vacuum supply for the transducer and EGR valve is controlled by the EGR valve solenoid. The solenoid is controlled by the vehicle's engine Electronic Control Unit (ECU). The ECU monitors the engine coolant temperature and other operating conditions to determine when EGR operation is desired.

If the electrical connector to the EGR solenoid is unplugged, the EGR valve will operate at all times. This results in poor engine performance and reduced driveability during certain operating conditions.



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Fig. Fig. 4: EGR valve solenoid-Premier and Monaco (1988-90 and early 1991 models)



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Fig. Fig. 5: EGR valve and transducer-Premier and Monaco (1988-90 and early 1991 models)

Engine vacuum flows through the EGR valve solenoid to the vacuum transducer through a connecting hose. Vacuum flows only when the solenoid is not energized (no voltage applied). The transducer is connected to the EGR valve by a vacuum hose and a backpressure hose. The transducer is controlled by exhaust backpressure and is ported to the exhaust manifold through a hose connecting it to the bottom of the EGR valve.



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Fig. Fig. 6: EGR system operation-Premier and Monaco (1988-90 and early 1991 models)



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Fig. Fig. 7: EGR system testing-Premier and Monaco (1988-90 and early 1991 models)

When the EGR solenoid is not energized and the engine backpressure entering the EGR valve inlet is strong enough to close the transducer bleed valve, vacuum will be supplied to the valve and EGR operation will begin. If backpressure is not strong enough to close the transducer bleed valve, the transducer will bleed off the vacuum preventing EGR operation.



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Fig. Fig. 8: Electric EGR Transducer (EET)-Premier and Monaco (late 1991 and all 1992 models)

When the EGR solenoid is de-energized by the ECU, vacuum flows to the transducer. The transducer is connected to the engine exhaust system by a small hose that connects to the base of the EGR valve.

TESTING



Except Premier and Monaco

See Figures 1 and 2

The symptoms of possible EGR system failure include: spark knock, engine hesitation on acceleration, or rough idle or stalling. Check the following items:

  1. Inspect all vacuum hose connections between the carburetor/throttle body, intake manifold, and vacuum transducer. All connections and hoses must be leak-free. Replace hoses that are hardened, melted or cracked. Inspect the vacuum passage in the throttle body. If necessary, remove the assembly from the engine and clean it.
  2.  
  3. Start the engine and allow it to warm-up to the point when the engine coolant is at least 150°F (65°C). Idle the engine in Neutral with the throttle closed, for over 70 seconds. Abruptly accelerate the engine to 2000-3000 rpm as you watch the groove in the EGR valve stem. Repeat the test several times to confirm that the system is operating normally. The stem should move visibly. If not, proceed with the tests that follow.
  4.  
  5. Connect a hand-operated vacuum pump or other confirmed source of vacuum that can be connected to the EGR valve vacuum motor, via rubber hose connections. If you are not using a pump equipped with a vacuum gauge, insert a "T'' junction with a vacuum gauge attached into the line, . Have the engine running at normal operating temperature and normal idle speed. Apply vacuum as you read the vacuum gauge. Listen to the engine as you gradually increase vacuum. The engine speed should begin to drop as vacuum reaches 2.0-3.5 in. Hg (6.75-13.18 kPa). Engine speed may drop quickly or even stall. This indicates exhaust gas is flowing through the system the way it is supposed to.
  6.  
  7. If both the acceleration of the vehicle and the externally applied vacuum show satisfactory results, the EGR system is functioning properly.
  8.  
  9. If engine speed does not drop off when applying external vacuum, remove both the EGR valve and EGR tube and check for plugged passages. Also check the intake manifold inlet passage. Clean or replace these components for restoration of proper flow.
  10.  

Early Premier and Monaco

If you are not sure whether your Premier or Monaco is designated as an early or late model, please refer to the model differentiation portion of this section.

EGR SOLENOID
  1. Bring the engine to normal operating temperature. Operate at idle speed.
  2.  
  3. Check the vacuum at the EGR solenoid vacuum source. Disconnect the hose and attach a vacuum gauge to it.
  4.  
  5. The vacuum should be a minimum of 15 in. Hg (56.5 kPa).
    1. If the vacuum is low, check the line for kinks, twists or a loose connection at the vacuum connector or intake manifold.
    2.  
    3. If the vacuum is OK, remove the vacuum gauge and reconnect the line and proceed to the next step.
    4.  

  6.  
  7. Check the vacuum at the solenoid output port.
  8.  
  9. Disconnect the line and attach a vacuum gauge to the output port. The vacuum reading should be zero (no vacuum) at this side of the solenoid.
    1. If the vacuum reading is zero, leave the gauge connected and proceed to the next step. However, if vacuum is present, have the solenoid/ECU operation checked by a qualified Chrysler dealership.
    2.  

  10.  
  11. Disconnect the electrical plug at the solenoid and note the vacuum at the output port. Vacuum should now be present at the output port.
    1. If vacuum is present, proceed to the EGR valve test.
    2.  
    3. If no vacuum is present, replace the solenoid with a new one.
    4.  

  12.  

EGR VALVE
  1. Unplug the solenoid electrical connector. Bypass the vacuum transducer and connect the EGR valve solenoid output hose directly to the nipple on the EGR valve and note the engine idle speed or quality.
    1. The engine should now idle roughly or stall. If this occurs, the valve is OK. Proceed to the vacuum transducer test.
    2.  
    3. If this does not occur, proceed to the next step.
    4.  

  2.  
  3. Disconnect the hose from the EGR valve and connect a hand vacuum pump to the EGR valve nipple.
  4.  
  5. Apply a minimum of 12 in. Hg (40.5 kPa) to the valve and note the engine idle. If the engine now idles roughly, inspect the vacuum lines between the vacuum connector on the intake manifold and the EGR valve, and the backpressure hose from the EGR valve base to the transducer for leaks. If no leaks are found, proceed to the vacuum transducer test.
  6.  
  7. If the idle did not change, remove the EGR valve, then inspect the valve and the exhaust passage in the manifold for blockage as necessary. If no blockage is present, replace the EGR valve with a new one.
  8.  

VACUUM TRANSDUCER
  1. Disconnect the transducer vacuum lines and backpressure line. Remove the transducer from its mounting position.
  2.  
  3. Plug the transducer output port with a vacuum cap.
  4.  
  5. Apply 1-2 psi (6.89-13.78 kPa) of air pressure the the transducer backpressure port. Air pressure can be supplied with a hand-operated air pump or compressed air (regulated to the correct psi).
  6.  
  7. Apply a minimum of 12 in. Hg (40.5 kPa) vacuum to the input port.
    1. If the transducer will not hold vacuum, replace it with a new one.
    2.  

  8.  

Late Premier and Monaco

If you are not sure whether your Premier or Monaco is designated as an early or late model, please refer to the model differentiation portion of this section.

ELECTRIC EGR TRANSDUCER-SOLENOID PORTION
  1. Bring the engine to normal operating temperature. Operate the vehicle at idle.
  2.  
  3. Check the vacuum at the Electric EGR Transducer (EET) vacuum source. Disconnect the hose and attach a vacuum gauge to it.
  4.  
  5. The vacuum should be a minimum of 15 in. Hg (50.65 kPa).
    1. If the vacuum is low, check the line for kinks, twists or a loose connection at the vacuum connector or intake manifold.
    2.  
    3. If the vacuum is OK, remove the gauge, reconnect the line and proceed to the next step.
    4.  

  6.  
  7. Have the EET operation checked by a qualified automotive technician.
  8.  

EGR VALVE
  1. Disconnect the hose from the EGR valve and connect a hand vacuum pump to the EGR valve nipple. Apply a minimum of 12 in. Hg (40.5 kPa) vacuum to the valve.
  2.  
  3. The engine should now idle roughly or stall. If this occurs, the valve is OK. Proceed to the vacuum transducer test.
  4.  
  5. If the idle did not change, remove the EGR valve and inspect the valve and the exhaust passage in the manifold for blockage. Remove any such blockage, if present. If no blockage was present, replace the EGR valve with a new one.
  6.  

ELECTRIC EGR TRANSDUCER-TRANSDUCER PORTION
  1. Disconnect the transducer vacuum lines, backpressure line and any electrical connectors. Remove the transducer from the vehicle.
  2.  
  3. Plug the Electric EGR Transducer (EET)-to-EGR valve port.
  4.  
  5. Apply 1-2 psi (6.89-13.78 kPa) of air pressure the the transducer backpressure port. Air pressure can be supplied with a hand-operated air pump or compressed air (regulated to the correct psi).
  6.  
  7. Apply a minimum of 12 in. Hg (40.5 kPa) vacuum to the input port.
    1. If the transducer will not hold vacuum, replace it with a new one. REMOVAL & INSTALLATION
    2.  

  8.  

EGR Valve

3.0L ENGINES

See Figure 1a

  1. On newer vehicles, unplug the electrical connectors from the Electric EGR Transducer (EET).
  2.  
  3. Remove the vacuum connectors from the EET. Inspect the vacuum lines for cracking, poor sealing due to hardness, or other damage. Replace the vacuum hoses, if necessary.
  4.  
  5. Remove the bolts attaching the EGR valve to the intake manifold. Remove the EGR valve.
  6.  
  7. 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.
  8.  



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Fig. Fig. 9: EGR system-3.0L engines, except Premier and Monaco

To install:
  1. Install a new gasket and the EGR valve onto the manifold. Install the two attaching bolts and torque to 16 ft. lbs. (22 Nm) for non-Premier or Monaco engines, and to 20 ft. lbs. (27 Nm) for Premier and Monaco engines.
  2.  
  3. Reconnect the vacuum lines and electrical wires to the electrical EGR transducer.
  4.  

3.3L AND 3.8L ENGINES

See Figures 2a and 11

  1. Remove the vacuum hose from the electric EGR transducer. 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 EET.
  4.  
  5. Remove the bolts attaching the EGR valve to the intake manifold.
  6.  
  7. Open the EGR transducer clip and remove the electric transducer.
  8.  
  9. Remove the EGR valve from the intake manifold.
  10.  
  11. 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.
  12.  



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Fig. Fig. 10: EGR system-3.3L and 3.8L engines



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Fig. Fig. 11: EGR mounting positions-3.3L and 3.8L engines

To install:
  1. Install a new gasket and the EGR valve onto the manifold. Install the two attaching bolts and torque to 16 ft. lbs. (22 Nm).
  2.  
  3. Install the electric transducer into the clip with the orientation tab in the slot and snap it closed.
  4.  
  5. Reconnect the vacuum lines and electrical wires to the electrical EGR transducer.
  6.  

EGR Tube

EXCEPT PREMIER AND MONACO
  1. Remove the EGR tube attaching bolts from the intake and exhaust manifolds.
  2.  
  3. Remove the EGR tube from the engine.
  4.  
  5. Clean all gasket surfaces. Inspect gasket surfaces for signs of cracking and replace the EGR tube or manifolds if cracking is found. Discard old gaskets and supply new ones.
  6.  

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

PREMIER AND MONACO
  1. The EGR tube is connected to the throttle body adapter and the right side exhaust manifold.
  2.  
  3. Unscrew the EGR tube line nut from the throttle body adapter.
  4.  
  5. Remove the EGR flange bolts from the right side exhaust manifold.
  6.  
  7. Remove the EGR tube.
  8.  
  9. Remove any old gasket material from the exhaust manifold.
  10.  

To install:
  1. Start the EGR tube into the throttle body adapter, but do not tighten the line nut at this time.
  2.  
  3. Install the EGR tube flange and new gasket on the exhaust manifold.
  4.  
  5. Tighten the flange mounting bolts to 14 ft. lbs. (19 Nm).
  6.  
  7. Tighten the line nut to 30 ft. lbs. (40 Nm).
  8.  

 
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