Vacuum DODGE TOWN AND COUNTRY 2001 Service Manual

EXHAUST GAS RECIRCULATION
TABLE OF CONTENTS
page page
EXHAUST GAS RECIRCULATION
DESCRIPTION............................3
OPERATION.............................3
VA LV E
DESCRIPTION............................3
OPERATION.............................4REMOVAL...............................4
INSTALLATION............................4
VALVE COOLER
DESCRIPTION............................4
REMOVAL...............................4
INSTALLATION............................5
EXHAUST GAS
RECIRCULATION
DESCRIPTION
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.
OPERATION
The system consists of:
²An EGR valve assembly. The valve is located on
the rear of the engine above the exhaust manfiold.
²An EGR solenoid.The EGR solenoid controls the
ªon timeº of the EGR valve.
²The ECM operates the EGR solenoid. The ECM
is located inside the vehicle under the instrument
panel.
²An EGR tube connects a passage in the EGR
valve to the rear of the exhaust manifold.
²The vacuum pump supplies vacuum for the EGR
solenoid and the EGR valve. This pump also supplies
vacuum for operation of the power brake boosterb
and the heating and air conditioning system. The
pump is located internally in the front of the engine
block and is driven by the crankshaft gear.
²Vacuum lines and hoses connect the various
components.
When the ECM supplies a variable ground signal
to the EGR solenoid, EGR system operation starts to
occur. The ECM will monitor and determine when tosupply and remove this variable ground signal. This
will depend on inputs from the engine coolant tem-
perature, throttle position and engine speed sensors.
When the variable ground signal is supplied to the
EGR solenoid, vacuum from the vacuum pump will
be allowed to pass through the EGR solenoid and on
to the EGR valve with a connecting hose.
Exhaust gas recirculation will begin in this order
when:
²The ECM determines that EGR system opera-
tion is necessary.
²The engine is running to operate the vacuum
pump.
²A variable ground signal is supplied to the EGR
solenoid.
²Variable vacuum passes through the EGR sole-
noid to the EGR valve.
²The inlet seat (poppet valve) at the bottom of
the EGR valve opens to dilute and recirculate
exhaust gas back into the intake manifold.
The EGR system will be shut down by the ECM
after 60 seconds of continuous engine idling to
improve idle quality.
VA LV E
DESCRIPTION
The EGR system consists of (Fig. 1):
²EGR valve
²EGR tube
²Vacuum hoses
²EGR cooler
²EGR solenoid
RGEXHAUST GAS RECIRCULATION25a-3
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OPERATION
The engines use Exhaust Gas Recirculation (EGR)
systems. The EGR system reduces oxides of nitrogen
(NOx) in engine exhaust and helps prevent detona-
tion (engine knock). Under normal operating condi-tions, engine cylinder temperature can reach more
than 3000ÉF. Formation of NOx increases proportion-
ally 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 com-
bustion.
REMOVAL
(1) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(2) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL).
(3) Disconnect EGR valve vacuum line.
(4) Remove EGR cooler to EGR valve retaining
bolts (Fig. 1).
(5) Remove EGR valve retaining nuts (Fig. 1) and
EGR valve.
INSTALLATION
(1) Clean gasket mating surfaces.
(2) Install EGR valve (Fig. 1). Torque nuts to
32.4N´m.
(3) Connect EGR cooler to EGR valve (Fig. 1).
Torque bolts to 32.4N´m
(4) Install front wiper unit (Refer to 8 - ELECTRI-
CAL/WIPERS/WASHERS/WIPER MODULE -
INSTALLATION).
(5) Install engine cover (Refer to 9 - ENGINE -
INSTALLATION) .
VALVE COOLER
DESCRIPTION
The EGR valve on this engine uses a cooler to cool
the exhaust gases before the returned to the intake
manifold (Fig. 2). The EGR cooler attaches to the
EGR valve and is cooled with engine coolant.
REMOVAL
(1) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(2) Partially drain cooling system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(3) Remove front wiper unit (Refer to 8 - ELEC-
TRICAL/WIPERS/WASHERS/WIPER MODULE -
REMOVAL) .
(4) Disconnect coolant supply and return lines at
EGR cooler (Fig. 2).
(5) Remove EGR cooler to exhaust manifold retain-
ing bolt (Fig. 2).
Fig. 1 EGR COMPONENTS
1 - HOSE CLAMP
2 - COOLANT HOSE
3 - HOSE CLAMP
4 - EGR VALVE RETAINING NUT
5 - E G R VA LV E
6 - COOLANT HOSE
7 - EGR VALVE GASKET
8 - EGR VALVE RETAINING STUDS
9 - EGR COOLER RETAINING BOLT
10 - HOSE CLAMP
11 - HOSE CLAMP
12 - EGR COOLER
13 - EGR COOLER TO EGR VALVE RETAINING BOLT
14 - TURBOCHARGER BRACKET
15 - TURBOCHARGER BRACKET RETAINING BOLT
16 - TURBOCHARGER DOWNPIPE
17 - TURBOCHARGER DOWNPIPE RETAINING NUT
18 - DOWNPIPE GASKET
19 - DOWNPIPE STUD
25a - 4 EXHAUST GAS RECIRCULATIONRG
VALVE (Continued)
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