Chrysler Neon 1995-1999 Repair Guide

Exhaust Gas Recirculation System

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OPERATION



See Figures 1, 2 and 3

The Exhaust Gas Recirculation (EGR) system reduces oxides of Nitrogen (NOx) in the engine exhaust and helps prevent detonation (engine knock). Under normal operating conditions, engine cylinder temperature can reach over 3000°F. The formation of NOx increases proportionally with the combustion temperature. To reduce the emission of these oxides, the cylinder temperature must be lowered. The system allows a predetermined amount of hot exhaust gas to recirculate and dilute the incoming air/fuel mixture. The diluted mixture lowers temperatures during combustion. The EGR system consists of the following components:



EGR tube
 
EGR valve
 
Electronic EGR Transducer (EET)
 
Connecting hoses
 

The electronic EGR transducer container an electrically operated solenoid and a backpressure transducer. The Powertrain Control Module (PCM) operated the solenoid, determining when to energize the solenoid. Exhaust system backpressure controls the transducer.



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Fig. Fig. 1: Exhaust Gas Recirculation (EGR) system components-1995 vehicles shown



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Fig. Fig. 2: Location of the EGR valve-1999 vehicle shown

When the PCM energizes the solenoid, vacuum doesn't reach the transducer. Vacuum flows to the transducer when the PCM de-energizes the solenoid. When exhaust system backpressure becomes high enough, it fully closes a bleed valve in the transducer. When the PCM de-energizes the solenoid and back-pressure closes the transducer bleed valve, vacuum flows through the transducer to operate the EGR valve.



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Fig. Fig. 3: Electronic EGR Transducer (EET) vacuum hose connection identification

De-engergizing the solenoid, but not fully closing the transducer bleed hole (because of low back-pressure), 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. This system does not allow EGR at idle.

COMPONENT TESTING



EGR System On-Board Diagnostics

The PCM performs an on-board diagnostic check of the EGR system. The diagnostic system uses t he electronic EGR transducer for the system tests.

The check activates only during certain conditions. When the conditions are met, the PCM energizes the transducer solenoid to disable the EGR. The PCM checks for a change the heated oxygen sensor signal. If the air/fuel ratio goes lean, the PCM will try to enrich the mixture. The PCM records a Diagnostic Trouble Code (DTC) if the EGR system is not operating properly. After registering a DTC, then PCM turns on the Check Engine lamp (malfunction indicator) after 2 consecutive trips. There are 2 types of failures sensed by the PCM; a short or open in the circuit or a mechanical failure or loss of vacuum. The Malfunction Indicator Lamp (MIL) denotes the need for service.

If you find a problem indicated by the MIL and a DTC is set, first check for proper operation of the EGR system. If the system tests properly check the system using Chrysler's DRB® or equivalent scan tool. Make sure to follow all of the instructions included with the scan tool.

EGR System Test

CAUTION
ALWAYS block the drive wheels and apply the parking brake anytime you are performing a test or adjustment in which the engine must be running!

1995-96 VEHICLES

A failed or malfunctioning EGR system can cause engine spark knock, hesitation, rough idle, stalling and/or increased emissions. The make sure the EGR system is operating properly, all passages and moving parts must be clean of deposits that could cause plugging or sticking. Make sure the hoses don't leak and replace any components that do leak.

Check the hose connections between the intake manifold, EGR solenoid and transducer and the EGR valve. Replace any hardened, cracked or leaking hoses. Repair or replace faulty connectors.

  1. Check the EGR control system and EGR valve with the engine fully warmed up and running. With the transmission in Neutral and the throttle closed, allow the engine to idle for about 70 seconds.
  2.  
  3. Abruptly accelerate the engine to about 2,000 rpm, but NOT over 3,000 rpm. The EGR valve stem should move when accelerating the engine.
  4.  
  5. Repease the test a few times to confirm movement. If the valve stem moves, the EGR system is operating properly. If the stem doesn't move, then EGR system is not operating properly.
  6.  

1997-99 VEHICLES

See Figures 4 and 5

  1. Check the condition of all EGR system hoses and tubes for leaks, blockage, cracks, kinks or hardening. Repair or replace as necessary before beginning the test.
  2.  
  3. Make sure the hoses at both the EGR valve and EGR valve control are connected properly and the electrical connector is firmly attached at the valve control.
  4.  



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Fig. Fig. 4: View of the EGR valve components fitting identification



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Fig. Fig. 5: View of the EGR valve fitting identification

  1. To check EGR system operation, connect the DRB® or equivalent scan tool to the 12-way data link connector. (The data link connector is located on the lower edge of the instrument panel near the steering column.) Make sure the follow all of the manufacturers instructions when connecting the scan tool and testing the EGR system.
  2.  
  3. After checking the system with the scan tool, proceed to the remaining EGR valve control tests.
  4.  

EGR Gas Flow Test

Use this test to see if exhaust gas is flowing through the EGR system

1995-96 VEHICLES
  1. Connect a suitable hand held vacuum pump to the EGR valve vacuum motor.
  2.  
  3. With the engine running at idle speed, slowly apply vacuum. Engine speed should begin to drop when the applied vacuum reaches 2.0-3.5 in. Hg. Engine speed may drop quickly or the engine may even stall. This indicates that EGR gas is flowing through the system.
  4.  
  5. If the engine speed doesn't drop when applying the vacuum, remove both the EGR valve and EGR tube and check for plugged passages and clean or replace, as necessary.
  6.  

1997-99 VEHICLES

See Figures 4 and 5

The engine must be started, running and at normal operation temperature for this test. This test is not to be used as a complete test of the EGR system, but in conjunction with the other system tests.

  1. All engines are equipped with 2 fittings located on the EGR valve, as shown in the accompanying figure. The upper fitting (located on the vacuum motor) supplies engine vacuum to a diaphragm within the EGR valve for valve operation. The lower fitting(located on the base of the EGR valve) is used to supply exhaust back-pressure to the EGR valve control.
  2.  
  3. Disconnect the rubber hose from the vacuum motor fitting on the top of the EGR valve vacuum motor.
  4.  
  5. Start the engine. Use a hand held vacuum gauge to apply about 5 in. of vacuum to the fitting on the EGR valve motor.
  6.  
  7. While applying vacuum, a minimum of 3 in. of vacuum , and with the engine running at idle speed, the idle speed should drop or the engine may even stall, if the vacuum is applied quickly. This indicates that exhaust gas is flowing through the EGR tube between the intake and exhaust manifolds.
  8.  
  9. If the engine speed did not change, the EGR valve may be defective or the EGR tube may be plugged with carbon, or the passages in the intake and exhaust manifold may be plugged with carbon. Perform the following to see if the components are plugged:
    1. Remove the EGR valve from the engine.
    2.  
    3. Applyg vacuum to the vacuum motor fitting and check the stem on the valve. If it's moving, then EGR valve is working properly and the problem is either a plugged EGR tube or plugged passages at the intake or exhaust manifolds (refer to the next step).
    4.  
    5. Remove the EGR tube between the intake and exhaust manifolds. Check and clean the EGR tube and its related openings on the manifolds.
    6.  

  10.  
  11. Do not try to clean the EGR valve. If the valve shows evidence of heavy carbon build-up near the base, replace it.
  12.  

EGR Valve Leakage Test

1997-99 VEHICLES

See Figures 4 and 5

If the engine will not idle, dies out on idle or the idle is rough or slow, the poppet valve, located at the base of the EGR valve, may be leaking in the closed position.

  1. The engine should be OFF for the following test.
  2.  
  3. Disconnect the rubber hose from the fitting at the top (vacuum motor) side of the EGR valve, and perform the following:
    1. Connect a hand-held vacuum pump to this fitting.
    2.  
    3. Apply 5 in. of vacuum to the pump, then observe the gauge reading on the pump.
    4.  
    5. If the vacuum falls off, the diaphragm in the EGR valve has ruptured.
    6.  
    7. Replace the EGR valve.
    8.  

  4.  

The EGR valve, valve control and attaching hoses are replaced as an assembly. back-pressure hose connects it to the back-pressure fitting on the EGR valve control. Disconnect this hose from the EGR valve fitting.

    1. Go on to the next step.
    2.  


  1. A small metal fitting (back-pressure fitting) is located at the base of the EGR valve. A rubber back-pressure hose connects it to the back-pressure fitting on the EGR valve control. Disconnect this hose from the EGR valve fitting.
  2.  

  1. Remove the air cleaner housing from the throttle body.
  2.  
  3. Using compressed air with an air nozzle with a rubber tip, apply about 50 psi of regulated air to the metal back-pressure fitting on the EGR valve.
  4.  
  5. By hand, open the throttle to the wide open position. Air should NOT be heard coming from the intake manifold while apply air pressure to the fitting.
  6.  
  7. If air CAN be heard coming from the intake manifold, the poppet valve is leaking at the bottom of the EGR valve. Replace the EGR valve.
  8.  

REMOVAL & INSTALLATION



EGR Valve and Electric Transducer

See Figures 1, 2, 6, 7, 8, 9, 10 and 11

If the EGR system is operating incorrectly and component replacement is necessary, keep in mind that because they are calibrated together, they must be replaced together.

On 1995 vehicles, the EGR valve and EET attach to the rear of the cylinder head. On 1996-99 vehicles,. the EGR valve is attaches to the rear of the cylinder head and the EGR transducer is attached to the air inlet duct.

  1. Disconnect the negative battery cable.
  2.  
  3. If necessary for access, disconnect the air inlet tube and unclip the fuse box.
  4.  
  5. For 1996-98 vehicles, remove the EGR transducer from the air inlet duct.
  6.  
  7. For 1996-99 vehicles, remove the air inlet duct.
  8.  
  9. Unfasten the EGR tube-to-EGR valve screws/bolts.
  10.  



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Fig. Fig. 6: Unfasten the EGR tube-to-valve mounting bolts

  1. Remove the EGR valve mounting screws.
  2.  



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Fig. Fig. 7: Remove the EGR valve mounting bolts

  1. Detach the vacuum supply tube from the EET solenoid.
  2.  



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Fig. Fig. 8: Disconnect the vacuum line from the solenoid

  1. Unplug the electrical connector from the solenoid.
  2.  



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Fig. Fig. 9: Unplug the solenoid electrical connector

  1. Remove the EGR valve and transducer.
  2.  
  3. Remove and discard the old gaskets. Thoroughly clean the gasket mating surfaces and/or passages.
  4.  



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Fig. Fig. 10: Remove and discard the bottom of the EGR valve



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Fig. Fig. 11: Don't forget to remove the EGR tube-to-valve gasket

To install:
  1. Using new gaskets, loosely install the EGR valve.
  2.  
  3. Finger-tighten the EGR tube fasteners.
  4.  
  5. Tighten the EGR tube fasteners to 95 inch lbs. (100 Nm).
  6.  
  7. Tighten the EGR valve mounting screws to 12 ft. lbs. (22 Nm).
  8.  
  9. If removed, install the air inlet duct.
  10.  
  11. Attach the vacuum supply tube and the electrical connector to the solenoid.
  12.  
  13. For 1996-99 vehicles, install the EGR transducer onto the air inlet duct.
  14.  
  15. If removed, fasten the fuse box in position and connect the air inlet tube.
  16.  
  17. Connect the negative battery cable.
  18.  

EGR Tube

See Figure 12

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

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the screws attaching the EGR tube to the intake manifold.
  4.  
  5. Unfasten the EGR tube-to-EGR valve screws.
  6.  
  7. Remove the EGR tube from the vehicle. Make sure to clean the gasket surface on the EGR valve and wipe the grommet on the intake manifold clean.
  8.  



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Fig. Fig. 12: Location of the EGR tube mounting screws

To install:

The rubber grommet that seals the EGR tube-to-intake manifold connection is reusable.

  1. Loosely install the EGR tube and fasteners.
  2.  
  3. Tighten the EGR tube-to-intake manifold plenum and EGR tube-to-EGR valve screws to 95 inch lbs.
  4.  
  5. Connect the negative battery cable.
  6.  

 
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