EXHAUST EMISSION CONTROLSÐ2.5L DIESEL ENGINE
INDEX
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DESCRIPTION AND OPERATION
EXHAUST GAS RECIRCULATION (EGR)
SYSTEM............................. 5
VACUUM HOSE ROUTING SCHEMATIC...... 5
DIAGNOSIS AND TESTING
EGR GAS FLOW TEST................... 6
ELECTRIC VACUUM MODULATOR (EVM)
TEST............................... 7REMOVAL AND INSTALLATION
EGR TUBE............................. 7
EGRVALVE ............................ 7
ELECTRIC VACUUM MODULATOR (EVM)..... 7
SPECIFICATIONS
TORQUE CHARTÐ2.5L DIESEL............ 8
DESCRIPTION AND OPERATION
VACUUM HOSE ROUTING SCHEMATIC
Vacuum for the EGR system is supplied by the
internal engine mounted vacuum pump. Refer to
EGR System Operation for vacuum pump informa-
tion. Vacuum harness routing for emission related
components is displayed in (Fig. 1).
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
GENERAL INFORMATION
The EGR system reduces oxides of nitrogen (NOx)
in the engine exhaust. This is accomplished by allow-
ing a predetermined amount of hot exhaust gas to
recirculate and dilute the incoming fuel/air mixture.
A malfunctioning EGR system can cause engine
stumble, sags or hesitation, rough idle, engine stall-
ing and poor driveability.
EGR SYSTEM OPERATION
The system consists of:
²An EGR valve assembly. The valve is located
behind the intake manifold (Fig. 2).
Fig. 1 Typical Hose Routing
Fig. 2 EGR Valve and Tube Location
NS/GSEMISSION CONTROL SYSTEM 25 - 5
