Pacifica, 2003-2005

Exhaust Gas Recirculation System

Print

Description & Operation



EGR Valve

The engines use Exhaust Gas Recirculation (EGR) systems. The EGR system reduces oxides of nitrogen (NOx) in engine exhaust and helps prevent detonation (engine knock). Under normal operating conditions, engine cylinder temperature can reach more than 3000F. Formation of NOx increases proportionally with 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 air/fuel mixture reduces peak flame temperature during combustion.

The electric EGR transducer contains an electrically operated solenoid and a backpressure 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 energizes the solenoid, vacuum does not 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 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 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. A failed or malfunctioning EGR system can cause engine spark knock, sags or hesitation, rough idle, engine stalling and increased emissions.

Removal & Installation



EGR Valve
3.5L
  1. Disconnect the negative and then the positive battery cable.
  2.  
  3. Remove battery.
  4.  
  5. Unlock and disconnect the electrical connector from the EGR valve.
  6.  
  7. Remove the 2 EGR tube bolts.
  8.  
  9. Remove the 2 mounting bolts for the EGR valve and gasket.
  10.  

To Install:

  1. Install the 2 mounting bolts into the EGR valve and gasket.
  2.  
  3. Loose install the EGR valve to cylinder head.
  4.  
  5. Loose install the EGR tube to EGR valve.
  6.  
  7. Tighten the EGR upper tube to EGR valve bolts to 11.3 Nm (100 inch lbs.) torque.
  8.  
  9. Connect and lock the electrical connector for the EGR valve.
  10.  
  11. Install the battery. Connect the positive then the negative battery cable.

    Click image to see an enlarged view

    Fig.

  12.  

3.8L Engine
  1. Disconnect negative battery cable.
  2.  
  3. Unlock and disconnect the electrical connector from the EGR valve.
  4.  
  5. Remove EGR tube bracket bolt. Remove the 2 EGR tube bolts.
  6.  
  7. Remove the 2 mounting bolts for the EGR valve and gasket.

    Click image to see an enlarged view

    Fig.

  8.  

To Install:

  1. Install the 2 mounting bolts into the EGR valve and gasket.
  2.  
  3. Loose install the EGR valve to cylinder head.
  4.  
  5. Loose install the EGR tube to EGR valve.
  6.  
  7. Install and tighten EGR tube bracket bolt.
  8.  
  9. Tighten the EGR tube to EGR valve bolts to 11.3 Nm (100 inch lbs.) torque.
  10.  
  11. Connect and lock the electrical connector for the EGR valve.
  12.  
  13. Install the battery. Connect the positive then the negative battery cable.
  14.  

 
label.common.footer.alt.autozoneLogo