EMISSION CONTROL
TSB Revision
ENGINE AND EMISSION CONTROL
17-111
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
GENERAL DESCRIPTION (EXHAUST GAS RECIRCULATION SYSTEM)
M1173005200338
The exhaust gas recirculation (EGR) system lowers
the nitrogen oxides (NOx) emission level. When the
air/fuel mixture combustion temperature is high, a
large quantity of NOx is generated in the combustion
chamber. Therefore, this system recirculates part of
exhaust gas from the exhaust port of the cylinder
head to the combustion chamber through the intake
manifold to decrease the air/fuel mixture combustion
temperature, resulting in reduction of NOx. The EGR
flow rate is controlled by the EGR valve so as not to
decrease the driveability.
OPERATION
When the engine coolant temperature is low, when
the engine is at idle or when a wide open throttle
operation is performed, the EGR valve is kept
closed, achieving no EGR. After warming up of the
engine, the EGR valve can be opened by the power-
train control module (PCM).
The PCM monitors the EGR system and illuminates
the Malfunction Indicator Lamp (SERVICE ENGINE
SOON or Check Engine Lamp) to indicate that there
is a malfunction.
SYSTEM DIAGRAM
AKX00353
VACUUM CONTROL VALVE
ON
OFF
MFI RELAY
BATTERY
PCM
VOLUME AIRFLOW
SENSOR
ENGINE COOLANT
TEMPERATURE SENSOR
CRANKSHAFT POSITION
SENSOR
EGR VALVE
AE
EGR VACUUM REGULATOR
SOLENOID VALVE