EMISSION CONTROL
TSB Revision
ENGINE AND EMISSION CONTROL
17-91
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
GENERAL DESCRIPTION (EXHAUST GAS RECIRCULATION SYSTEM)
M1173005200305
The exhaust gas recirculation system (EGR) 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 (Stepper
Motor) for driveability quality.
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 (Stepper
Motor) is kept closed, achieving no EGR. After warm-
ing up of the engine, the EGR valve (Stepper Motor)
can be opened by the powertrain control module
(PCM).
The PCM monitors the EGR system and illuminates
the check engine/malfunction indicator lamp to indi-
cate that there is a malfunction.
SYSTEM DIAGRAM
<2.4L ENGINE>
AK300557 AD
MASS AIRFLOW SENSOR
ENGINE COOLANT
TEMPERATURE SENSOR
CRANKSHAFT POSITION
SENSOR
PCM
MFI RELAY
BATTERY
EGR VALVE
(STEPPER MOTOR)