GM Cavalier/Sunfire 1995-2000 Repair Guide

Exhaust Gas Recirculation (EGR) System

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OPERATION



See Figure 1



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Fig. Fig. 1: Exhaust Gas Recirculation (EGR) system flow

The 2.3L engine does not use an EGR valve.

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. There are two types of EGR valves used on the 1995-00 GM J-body vehicles. The EGR vacuum diagram for your particular vehicle is displayed on the Vehicle Emission Control Information (VECI) label.

Negative Backpressure EGR Valve

See Figure 2

The negative backpressure EGR valve, used on the 1995 2.2L engine, varies the amount of exhaust gas flow into the intake manifold depending on manifold vacuum and variations in exhaust backpressure. An air bleed valve, located inside the EGR valve assembly acts as a vacuum regulator. The bleed valve controls the amount of vacuum in the vacuum chamber by bleeding vacuum to outside air during the open phase of the cycle. The diaphragm on the valve has an internal air bleed hole which is held closed by a small spring when there is no exhaust backpressure. Engine vacuum opens the EGR valve against the pressure of a spring. When manifold vacuum combines with negative exhaust backpressure, the vacuum bleed hole opens and the EGR valve closes. This valve will open if vacuum is applied with the engine not running.



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Fig. Fig. 2: The negative backpressure EGR valve is used on the 1995 2.2L engine

Linear EGR Valve (199600 2.2L And 2.4L Engines)

See Figure 3



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Fig. Fig. 3: The linear EGR valve equipped on the 2.2L and 2.4L engines

The linear EGR valve, used on the 1996-00 2.2L and 2.4L engines, is designed to accurately apply EGR to an engine, independent of intake manifold vacuum. The valve controls EGR flow from the exhaust to the intake manifold through an orifice with a PCM controlled pintle. During operation, the PCM controls pintle position by monitoring the pintle position feedback signal. The PCM uses information from the Engine Coolant Temperature (ECT) sensor, Throttle Position (TP) sensor and the Mass Air Flow (MAF) sensor to determine the appropriate rate of flow for a particular engine operating condition.

TESTING



Negative Backpressure EGR Valve (1995 Vehicles With 2.2L Engine Only)

See Figures 4 and 5



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Fig. Fig. 4: Negative backpressure EGR system check (1 of 2)-95 2.2L engines



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Fig. Fig. 5: Negative backpressure EGR system check (2 of 2)-95 2.2L engines

Linear EGR Valve (199600 2.2L And 2.4L Engines)

See Figures 6 and 7



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Fig. Fig. 6: Linear EGR valve diagnostic chart (1 of 2)



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Fig. Fig. 7: Linear EGR valve diagnostic chart (2 of 2)

REMOVAL & INSTALLATION



EGR Valve

See Figures 8, 9, 10, 11, 12 and 13



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Fig. Fig. 8: EGR valve mounting-1995 2.2L engine



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Fig. Fig. 9: Detach the connector on the EGR valve



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Fig. Fig. 10: Remove the two EGR valve retaining bolts and ...



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Fig. Fig. 11: ... remove the EGR valve from the engine



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Fig. Fig. 12: The EGR valve has a gasket, always replace the gasket even if you are using the old EGR valve



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Fig. Fig. 13: Thoroughly clean the EGR valve mounting surface

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner outlet tube.
  4.  
  5. Detach the EGR valve connector.
  6.  
  7. Remove the two bolts and remove the EGR valve.
  8.  
  9. Thoroughly clean the EGR mounting surface.
  10.  

To install:
  1. Install a new gasket and position the EGR valve onto the engine.
  2.  
  3. Tighten the two EGR valve retaining bolts to 16-22 ft. lbs. (22-30 Nm).
  4.  
  5. Attach the EGR valve connector.
  6.  
  7. Install the air cleaner outlet tube.
  8.  
  9. Connect the negative battery cable.
  10.  

EGR Control Solenoid (1995 Vehicles With 2.2L Engine Only)

See Figure 14

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the MAP sensor, as outlined in this section.
  4.  
  5. Detach the electrical connector from the solenoid.
  6.  
  7. Tag and disconnect the vacuum hoses.
  8.  
  9. Unfasten the retaining screw, then remove the EGR solenoid.
  10.  



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Fig. Fig. 14: EGR control valve relay solenoid mounting- 1995 2.2L engine

To install:
  1. Install the solenoid and bracket and tighten the screw to 17 ft. lbs. (24 Nm) for 1992 vehicles or to 2 ft. lbs. (30 Nm) for 1993-95 vehicles. Do NOT overtighten the retainers.
  2.  
  3. Connect the vacuum hoses, as tagged during removal.
  4.  
  5. Attach the electrical connector to the solenoid.
  6.  
  7. Install the seal on the MAP sensor, then install the MAP sensor and tighten the screws to 27 inch lbs. (3 Nm).
  8.  
  9. Connect the negative battery cable.
  10.  

 
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