Description & Operation
The EGR system consists of:
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 back-pressure transducer Electric EGR Transducer The Powertrain Control Module (PCM) operates the solenoid. The PCM determines when to energize the solenoid. Exhaust system back-pressure 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 back-pressure 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.
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.
If the EGR system operates incorrectly, replace the entire EGR valve and transducer together. The EGR valve and electrical transducer are calibrated together.
Removal & Installation
- Remove the air cleaner lid, disconnect the inlet air temperature sensor and makeup air hose.
- Remove the negative battery cable.
- Loosen the bolts at the intake manifold.
- Remove EGR tube bolts at EGR Valve.
- Unclip EGR transducer bracket and remove.
- Disconnect the vacuum supply hose to EGR transducer solenoid.
- Unlock the connector then disconnect the electrical connector from solenoid.
- Remove the 2 bolts at EGR valve to cylinder head. Remove EGR valve and transducer.
- Clean gasket surfaces. Discard old gaskets. If necessary, clean EGR passages.
- Connect vacuum supply tube to solenoid.
- Attach electrical connector to solenoid.
- Install EGR transducer into the bracket and snap closed.
- Loosely install EGR valve with new gaskets.
- Finger-tighten EGR tube fasteners.
- Tighten EGR valve mounting screws to 22 Nm (195 inch lbs.) torque.
- Tighten EGR tube fasteners to 11 Nm (97 inch lbs.) torque.
- Be sure to route hoses and wiring away from hot-contact surfaces.
- Install the negative battery cable.
- Install the air cleaner lid; connect the inlet air temperature sensor and makeup air hose.