Mitsubishi Eclipse 1990 Service Manual page 820

EXHAUST GAS RECIRCULATION
GENERAL INFORMATION
The exhaust gas recirculation (EG
the nitrogen oxide
air/fuel mixture combustion temperature is high,
a large quantity of nitrogen oxides
ated in the combustion
system recirculates part of emission gas from the
exhaust port of the cylinder head to the combustion
OPERATION
When the engine coolant
the engine is at idle or when a wide open throttle
operation is performed, the EGR valve is kept
closed, achieving no EGR.
The manifold differential pressure sensor is located
in the intake manifold plenum. This sensor detects
variations in the manifold
the EGR solenoid is momentarily operated. If the
manifold negative pressure
tem is normal.
SYSTEM DIAGRAM
Engine (Turbo)>
system lowers
emission level. When the
is gener-
Therefore, this
is low, when
pressure when
the EGR sys-
EGR valve
TSB Revision
(Turbo)
(EGR) SYSTEM
chamber through the intake manifold to decrease
the mixture combustion temperature, result-
ing in reduction of
The EGR flow rate is controlled by the EGR valve
so as not to decrease the
In normal vehicle operation performed after warm-
ing up of the engine, the EGR valve is opened
to carry out EGR.
The ECM uses this to check the operation of the,
EGR system. If a problem is found, the check en-'
indicator light illuminates to warn
the driver that a problem has occurred.
solenoid
EGR
Engine control
module
I
relay
Engine>
and
17300520205
sensor
Engine coolant
temperature sensor
sensor
Manifold differential
pressure sensor,