Page 2124 of 2177

NATURAL VAC LEAK
DETECTION ASSY
REMOVAL
(1) Disconnect thew negative battery cable.
(2) Raise vehicle and support (Fig. 4).
(3) Unlock and disconnect the electrical connector.
(4) Remove the hoses from the NVLD valve.
(5) Remove the 2 fasteners.
(6) Remove the valve and bracket from vehicle
(Fig. 5).
(7) Remove valve from bracket (Fig. 6).
INSTALLATION
(1) Install NVLD valve to the bracket (Fig. 6).
(2) Install valve and bracket to the vehicle (Fig. 5).
(3) Install the 2 mounting bolts and tighten.
(4) Install the electrical connector and lock.
(5) Install the 2 hoses and lock the clamps.
(6) Lower vehicle.
LEAK DETECTION PUMP
REMOVAL
(1) Disconnect the negative battery cable.
(2) Raise and support the vehicle.
(3) Remove 3 hoses (Fig. 7).
(4) Remove the electrical connector (Fig. 8).
(5) Remove the 3 screws and remove LDP pump.
INSTALLATION
(1) Install LDP.
(2) Install the 3 screws and tighten (Fig. 8).
(3) Install the electrical connector.
(4) Install the 3 hoses (Fig. 7).
(5) Lower vehicle.
(6) Connect the negative battery cable.
Fig. 4 NVLD LOCATION
Fig. 5 NVLD REMOVAL/INSTALLATION
Fig. 6 NVLD VALVE AND BRACKET
RSEVAPORATIVE EMISSIONS25-13
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Page 2133 of 2177

VA LV E
DESCRIPTION
The EGR system consists of:
²EGR tube (connects a passage in the intake
manifold to the exhaust port in the cylinder head)
²EGR valve
²Electronic EGR Transducer
²Connecting hoses
OPERATION
Refer to Monitored Systems - EGR Monitor in this
group for more information.
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.
The electric EGR transducer contains an electri-
cally operated solenoid and a back-pressure trans-
ducer (Fig. 2). The Powertrain Control Module (PCM)
operates the solenoid. The PCM determines when toenergize the solenoid. Exhaust system back-pressure
controls the transducer.
When the PCM energizes the solenoid, vacuum
does not reach the transducer. Vacuum flows to the
transducer when the PCM de-energizes the solenoid.
When exhaust system back-pressure becomes high
enough, it fully closes a bleed valve in the trans-
ducer. When the PCM de-energizes the solenoid and
back-pressure closes the transducer bleed valve, vac-
uum flows through the transducer to operate the
EGR valve.
Fig. 1 EGR VALVE AND TUBE 2.4L
1 - EGR Tube
2 - EGR Valve
Fig. 2 EGR Valve and Transducer - Typical
1 - DIAPHRAGM
2 - PISTON
3 - SPRING
4 - EGR VALVE ASSEMBLY
5 - VACUUM MOTOR
6 - VACUUM MOTOR FITTING
7 - VACUUM OUTLET FITTING TO EGR VALVE
8 - EGR VALVE CONTROL ASSEMBLY
9 - ELECTRIC SOLENOID PORTION OF VALVE CONTROL
10 - VACUUM INLET FITTING FROM ENGINE
11 - BACK-PRESSURE HOSE
12 - TRANSDUCER PORTION OF VALVE CONTROL
13 - ELECTRICAL CONNECTION POINT
14 - EGR VALVE BACK-PRESSURE FITTING
15 - EXHAUST GAS INLET
16 - STEM PROTECTOR AND BUSHING
17 - BASE
18 - MOVEMENT INDICATOR
19 - POPPET VALVE
20 - SEAT
21 - EXHAUST GAS OUTLET
25 - 22 EXHAUST GAS RECIRCULATIONRS
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Page 2134 of 2177

De-energizing the solenoid, but not fully closing the
transducer bleed hole (because of low back-pressure),
varies the strength of vacuum applied to the EGR
valve. Varying the strength of the vacuum changes
the amount of EGR supplied to the engine. This pro-
vides the correct amount of exhaust gas recirculation
for different operating conditions.
This system does not allow EGR at idle.
A failed or malfunctioning EGR system can cause
engine spark knock, sags or hesitation, rough idle,
engine stalling and increased emissions.
REMOVAL - 2.4L
The EGR valve and Electrical EGR Transducer are
serviced as an assembly (Fig. 1).
(1) Disconnect vacuum tube from electric EGR
transducer. Inspect vacuum tube for damage.
(2) Remove electrical connector from solenoid.
(3) Remove EGR tube bolts from EGR valve.
(4) Remove EGR valve from cylinder head adaptor.
(5) Clean gasket surface and discard old gasket.
Check for any signs of leakage or cracked surfaces.
Repair or replace as necessary.
INSTALLATION - 2.4L
The EGR valve and Electrical EGR Transducer are
serviced as an assembly (Fig. 1).
(1) Assemble EGR valve with new gasket onto the
cylinder head adaptor.
(2) Loose assemble the bolts from EGR valve to
EGR tube.
(3) Loose assemble the bolts from EGR valve to
cylinder head.
(4) Tighten bolts from EGR valve to cylinder head
to 22.8 N´m (200 25 in. lbs.) torque.
(5) Tighten bolts from EGR valve to EGR tube to
11.9 N´m (105 20 in. lbs.) torque.
(6) Reconnect vacuum hose and electrical connec-
tor to electrical EGR transducer.
RSEXHAUST GAS RECIRCULATION25-23
VALVE (Continued)
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