1999 DODGE NEON Service Repair Manual

The label contains the vehicle's emission specifica-
tions and vacuum hose routings. All hoses must be
connected and routed according to the label.
DIAGNOSIS AND TESTING
LEAK DETECTION PUMP
Refer to the appropriate Powertrain Diagnostic
Procedures Manual for testing procedures.
PCV VALVE TEST
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE PERFORMING ANY TEST
OR ADJUSTMENT WITH THE ENGINE OPERATING.
With the engine idling, remove the PCV valve from
its attaching point. If the valve is operating properly,
a hissing noise will be heard and a strong vacuum
felt when placing a finger over the valve inlet (Fig.
9). With the engine off, shake the valve. The valve
should rattle when shaken. Replace the valve if it
does not operate properly.Do not attempt to clean
the PCV valve.
VACUUM SCHEMATIC
If any difference exists between the diagram on the
Vehicle Emission Control Information (VECI) label
and this illustration, refer to the label on the vehicle.
Fig. 9 PCV Test ÐTypical
25 - 14 EMISSION CONTROL SYSTEMSPL
DESCRIPTION AND OPERATION (Continued)

ENGINE VACUUM SCHEMATICÐSOHC
PLEMISSION CONTROL SYSTEMS 25 - 15
DIAGNOSIS AND TESTING (Continued)

ENGINE VACUUM SCHEMATICÐDOHC
25 - 16 EMISSION CONTROL SYSTEMSPL
DIAGNOSIS AND TESTING (Continued)

REMOVAL AND INSTALLATION
LEAK DETECTION PUMP REPLACEMENT
REMOVAL
(1) Raise and support vehicle on a hoist.
(2) Remove right front wheel.
(3) Remove splash shield.
(4) Disconnect vacuum lines from EVAP canister.
(5) Push locking tab on electrical connector to
unlock and remove connector.
(6) Remove 3 nuts from EVAP canister and remove
canister.
(7) Remove pump and bracket as an assembly.
(8) Remove pump from bracket.
INSTALLATION
(1) Install pump to bracket and tighten bolts to 1.2
N´m (10.6 in. lbs.).(2) Install pump and bracket assembly to body and
tighten bolts to 10 N´m (90 in. lbs.).
(3) Install EVAP canister to bracket and tighten
nutts to 5.6 N´m (50 in. lbs.).
(4) Install electrical connetor to pump and push
locking tab to lock.
(5)Before installing hoses to LDP, make sure
they are not cracked or split. If a hose leaks, it
will cause the Check Engine Lamp to illumu-
nate.Connect lines to EVAP canister and LDP.
(6) Use the DRB scan tool, verify proper operation
of LDP.
(7) Install splash shield.
(8) Install wheel.
(9) Lower vehicle
PLEMISSION CONTROL SYSTEMS 25 - 17

EXHAUST GAS RECIRCULATION (EGR) SYSTEM
INDEX
page page
DESCRIPTION AND OPERATION
EXHAUST GAS RECIRCULATION (EGR)
SYSTEM............................. 18
DIAGNOSIS AND TESTING
EGR GAS FLOW TEST................... 19
EGR SYSTEM ON-BOARD DIAGNOSTICS..... 19
EGR SYSTEM TEST..................... 19EGR VALVE CONTROL (TRANSDUCER) TEST . 20
EGR VALVE LEAKAGE TEST............... 20
REMOVAL AND INSTALLATION
EGR TUBE............................. 22
EGRVALVE ............................ 21
SPECIFICATIONS
TORQUE.............................. 22
DESCRIPTION AND OPERATION
EXHAUST GAS RECIRCULATION (EGR) SYSTEM
Refer to Monitored Systems - EGR Monitor in this
group for more information.
The EGR system reduces oxides of nitrogen (NOx)
in engine exhaust and helps prevent detonation
(engine knock). Under normal operating conditions,
engine cylinder temperature can reach more than
3000ÉF. Formation of NOx increases proportionally
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 mix-
ture reduces peak flame temperature during combus-
tion.
The EGR system consists of (Fig. 1):
²EGR tube
²EGR valve
²Electronic EGR Transducer (EET)
²Connecting hoses.The electronic 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 to
energize 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.
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.
Fig. 1 EGR System
Fig. 2 Electronic EGR Transducer
25 - 18 EMISSION CONTROL SYSTEMSPL

DIAGNOSIS AND TESTING
EGR SYSTEM ON-BOARD DIAGNOSTICS
The PCM performs an on-board diagnostic check of
the EGR system. The diagnostic system uses the
electronic EGR transducer for the system tests.
The diagnostic check activates only during selected
engine/driving conditions. When the conditions are
met, the PCM energizes the transducer solenoid to
disable the EGR. The PCM checks for a change in
the heated oxygen sensor signal. If the air-fuel mix-
ture goes lean, the PCM will attempt to enrichen the
mixture. The PCM registers a Diagnostic Trouble
Code (DTC) if the EGR system is not operating cor-
rectly. After registering a DTC, the PCM turns on the
malfunction indicator (Check Engine) lamp after 2
consecutive trips. There are 2 types of failures sensed
by the PCM. The first is a short or open in the elec-
trical solenoid circuit. the second is a mechhanical
failure or loss of vacuum. The Malfunction Indicator
Lamp (MIL) indicates the need for service.
If a problem is indicated by the MIL and a DTC for
the EGR system is set, check for proper operation of
the EGR system. Use the System Test, EGR Gas
Flow Test. If the EGR system tests properly, check
the system using the DRB scan tool. Refer to
On-Board Diagnosis sections in this Group. Also,
refer to the DRB scan tool and the appropriate Pow-
ertrain Diagnostics Procedure manual.
EGR SYSTEM TEST
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE TESTING THE EGR SYS-
TEM.
(1) Check the condition of all EGR system hoses
and tubes for leaks, blockages, cracks, kinks and
hardening of rubber hoses. Repair and correct these
conditions before performing any tests.
(2) Be sure the hoses at both the EGR valve and
EGR valve control are connected to the proper fit-
tings (Fig. 3).
(3) Be sure the electrical connector is firmly con-
nected at the valve control.
(4) To check EGR system operation, connect the
DRB scan tool to the 16±way data link connector.
The data link connector is located on the lower edge
of the instrument panel near the steering column.
Refer to the appropriate Powertrain Diagnostic Pro-
cedures service manual for operation of the DRB
scan tool when diagnosing the EGR system.
(5) After checking the system with the DRB scan
tool, proceed to the following EGR Valve Leakage and
EGR Valve Control Tests and repair as necessary.
EGR GAS FLOW TEST
Use the following test procedure to determine if
exhaust gas is flowing through the EGR valve. It can
also be used to determine if the EGR tube is plugged,
or the system passages in the intake or exhaust man-
ifolds are plugged.
This is not to be used as a complete test of the
EGR system.
The engine must be started, running and warmed
to operating temperature for this test.
(1) All engines are equipped with two fittings
located on the EGR valve (Fig. 4). The upper fitting
(located on the vacuum motor) supplies engine vac-
uum to a diaphragm within the EGR valve for valve
operation. The lower fitting (located on the base of
the EGR valve) is used to supply exhaust back-pres-
sure to the EGR valve control.
(2) Disconnect the rubber hose at the vacuum
motor fitting (Fig. 4) on the top of the EGR valve
vacuum motor.
(3) Connect a hand-held vacuum pump to this fit-
ting.
(4) Start the engine.
(5) Slowly apply 5 inches of vacuum to the fitting
on the EGR valve motor.
(6) While applying vacuum, a minimum of 3 inches
of vacuum, and with the engine running at idle
Fig. 3 EGR Value and EGR Value ÐTypical
PLEMISSION CONTROL SYSTEMS 25 - 19

speed, the idle speed should drop or the engine may
even stall, if the vacuum is applied quickly. This is
indicating that exhaust gas is flowing through the
EGR tube between the intake and exhaust manifolds.
(7) If the engine speed did not change, the EGR
valve may be defective, or EGR tube may be plugged
with carbon, or the passages in the intake and
exhaust manifolds may be plugged with carbon.
(a) Remove EGR valve from engine. Refer to
EGR Valve Removal in this group.
(b) Apply vacuum to the vacuum motor fitting
and observe the stem on the EGR valve. If the
stem is moving, it can be assumed that the EGR
valve is functioning correctly. The problem is in
either a plugged EGR tube or plugged passages at
the intake or exhaust manifolds, refer to step (c). If
the stem will not move, replace the EGR valve.
Note: The EGR valve, valve control and attaching
hoses are serviced as one unit. Refer to EGR Valve
Removal/Installation in this group.
(c) Remove the EGR tube between the intake
and exhaust manifolds. Check and clean the EGR
tube and its related openings on the manifolds.
Refer to EGR Tube in this group for procedures.
(8) Do not attempt to clean the EGR valve. If the
valve shows evidence of heavy carbon build-up near
the base, replace it.
EGR VALVE LEAKAGE TEST
This is not to be used as a complete test of the
EGR system.
If the engine will not idle, dies out on idle, or idle
is rough or slow, the poppet valve (Fig. 3) at the baseof the EGR valve may be leaking in the closed posi-
tion.
(1) The engine should be off for the following test.
(2) Disconnect the rubber hose from the fitting
(Fig. 3) at the top (vacuum motor) side of the EGR
valve.
(a) Connect a hand-held vacuum pump to this
fitting.
(b) Apply 15 inches of vacuum to the pump.
(c) Observe the gauge reading on the pump.
(d) If vacuum falls off, the diaphragm in the
EGR valve has ruptured.
(e) Replace the EGR valve. Note: The EGR
valve, valve control and attaching hoses are ser-
viced as one assembly. Refer to EGR Valve Remov-
al/Installation in this group.
(f) Proceed to the next step.
(3) A small metal fitting (back-pressure fitting) is
located at the base of the EGR valve (Fig. 3). A rub-
ber back-pressure hose connects it to the back-pres-
sure fitting on the EGR valve control. Disconnect this
rubber hose at the EGR valve fitting.
(4) Remove the air cleaner housing from the throt-
tle body.
(5) Using compressed air, and using an air nozzle
with a rubber tip, apply approximately 50 psi of reg-
ulated shop air to the metal back- pressure fitting on
the EGR valve.
(6) By hand, open the throttle to the wide open
position. AirSHOULD NOT BE HEARDemitting
from the intake manifold while applying air pressure
at the back-pressure fitting.
(7) If airCAN BE HEARDemitting from the
intake manifold, the poppet valve (Fig. 3) is leaking
at the bottom of the EGR valve. Replace the EGR
valve. Note: The EGR valve, valve control and
attaching hoses are serviced as one assembly. Refer
to EGR Valve Removal/Installation in this group. Do
not attempt clean the old EGR valve.
EGR VALVE CONTROL (TRANSDUCER) TEST
TESTING ELECTRICAL SOLENOID PORTION
OF VALVE
This is not to be used as a complete test of the
EGR system.
Electrical operation of the valve should be checked
with the DRB scan tool. Refer to the appropriate
Powertrain Diagnostic Procedures service manual for
operation of the DRB scan tool. Replace solenoid if
necessary, unit serviced only as an assembly.
TESTING VACUUM TRANSDUCER PORTION
OF VALVE
The first part of this test will determine if the
transducer diaphragm at the back-pressure side of
the valve has ruptured or is leaking. The second part
Fig. 4 Typical EGR Valve
25 - 20 EMISSION CONTROL SYSTEMSPL
DIAGNOSIS AND TESTING (Continued)

of the test will determine if engine vacuum (full-man-
ifold) is flowing from the inlet to the outlet side of
the valve. This is not to be used as a complete test of
the EGR system.
(1) Disconnect the rubber back-pressure hose from
the fitting at the bottom of EGR valve (Fig. 3).
(2) Connect a hand-held vacuum pump to this fit-
ting.
(3) Apply 10 inches of vacuum to this fitting.
(4) If vacuum falls off, the valve diaphragm is
leaking.
(5) Replace the Complete EGR valve assembly.
Proceed to next step for further testing.
(6) Reconnect hose to EGR valve.
(7) Remove the vacuum supply hose at the vacuum
inletfitting (Fig. 3) on the EGR solenoid.
(8) Connect a vacuum gauge to this disconnected
vacuum line.
(9) Start the engine and bring to operating tem-
perature. Hold engine speed at approximately 1500
rpm.
(10) Check for steady engine vacuum (full-mani-
fold) at this hose.
(11) If engine vacuum (full-manifold) is not
present, check vacuum line to engine and repair as
necessary before proceeding to next step.
(12) Reconnect the rubber hose to the vacuum
inletfitting (Fig. 3) on the EGR valve.
(13) Disconnect the rubber hose at the vacuum
outletfitting (Fig. 3) on the EGR valve.
(14) Connect a vacuum gauge to this fitting.
(15) Disconnect the electrical connector (Fig. 3) at
the valve control. This will simulate an open circuit
(no ground from the PCM) at the valve, activating
the valve. A DTC will be set in the PCM that must
be erased after testing is complete.
(16) Start the engine and bring to operating tem-
perature.
(17) Hold the engine speed to approximately 2000
rpm while checking for engine vacuum (full-manifold)
at this fitting.To allow full manifold vacuum to
flow through the valve, exhaust back-pressure
must be present at valve. It must be high
enough to hold the bleed valve in the trans-
ducer portion of the valve closed.Have a helper
momentarily (a second or two) hold a rag over the
tailpipe opening to build some exhaust back-pressure
while observing the vacuum gauge. Heavy gloves
should be worn.Do not cover the tailpipe open-
ing for an extended period of time as damage to
components or overheating may result.(18) As temporary back-pressure is built, full man-
ifold vacuum should be observed at the vacuum out-
let fitting. Without back-pressure, and engine at
approximately 2000 rpm, the gauge reading will be
low. This low reading is normal. At idle speed, the
gauge reading may be erratic. This is also normal.
(19) If full manifold vacuum is not present at the
outlet fitting, but was present at the inlet fitting,
replace the valve. Note: The EGR valve, valve control
and attaching hoses are serviced as one assembly.
Refer to EGR Valve Removal/Installation in this
group.
REMOVAL AND INSTALLATION
EGR VALVE
If the EGR system operates incorrectly, replace the
entire EGR valve and transducer together. The EGR
valve and electrical transducer are calibrated
together.
REMOVAL
The EGR valve attaches to the rear of the cylinder
head (Fig. 5). EGR transducer is attached to the air
inlet duct.
(1) Remove EGR transducer from air inlet duct.
(2) Disconnect vacuum supply tube from EGR
transducer solenoid.
(3) Disconnect electrical connector from solenoid.
(4) Remove air inlet duct.
(5) Remove EGR tube to EGR valve screws.
(6) Remove EGR valve mounting screws. Remove
EGR valve and transducer.
(7) Clean gasket surfaces. Discard old gaskets. If
necessary, clean EGR passages.
INSTALLATION
(1) Loosely install EGR valve with new gaskets.
(2) Finger tighten EGR tube fasteners.
(3) Tighten EGR tube fasteners to 11 N´m (95 in.
lbs.) torque.
(4) Tightening EGR valve mounting screws to 22
N´m (200 in. lbs.) torque.
(5) Install air inlet duct.
(6) Connect vacuum supply tube to solenoid.
(7) Attach electrical connector to solenoid.
(8) Install EGR transducer onto air inlet duct.
PLEMISSION CONTROL SYSTEMS 25 - 21
DIAGNOSIS AND TESTING (Continued)