2001 DODGE TOWN AND COUNTRY Engine

A pressure build up within the evaporative system
may cause pressure on the lower side of the LDP dia-
phragm. This will cause the LDP diaphragm to
remain in its9up9position (stuck in the up position).
This condition can occur even when the solenoid
valve is deenergized. This condition can be caused by
previous cycling (pumping) of the LDP by the techni-
cian (dealer test). Another way that this condition is
created is immediately following the running of the
vehicle evaporative system monitor. In this case, the
PCM has not yet opened the proportional purge sole-
noid in order to vent the pressure that has been built
up in the evaporative system to the engine combus-
tion system. The technician will need to vent the
evaporative system pressure via the vehicle fuel filler
cap and its fuel filler secondary seal (if so equipped
in the fuel filler neck). This will allow the technician
to cycle the LDP and to watch switch state changes.
After passing the leak detection phase of the test,
system pressure is maintained until the purge sys-
tem is activated, in effect creating a leak. If the dia-
phragm falls (as is expected), causing the reed switch
to change state, then the diagnostic test is completed.
When one of the evaporative system leak monitors
begins its various tests, a test is performed to deter-
mine that no part of the evaporative system is
blocked. In this test, the LDP is cycled (pumped) a
calibrated (few) number of times. Pressure should not
build up in the evaporative system. If pressure is
present, then LDP diaphragm is forced to stay in its
9up9position. The reed switch now stays open and
the PCM senses this open (incorrect) state. The evap-
orative system monitor will fail the test because of a
detected obstruction within the system.
Possible causes:
²Open or shorted LDP switch sense circuit
²Leak Detection Pump switch failure
²Open fused ignition switch output
²Restricted, disconnected, or blocked manifold
vacuum source
²Obstruction of hoses or lines
²PCM failure
REMOVAL
(1) Disconnect the negative battery cable.
(2) Raise and support the vehicle.
(3) Remove 3 hoses (Fig. 4).
(4) Remove the electrical connector (Fig. 5) .
(5) Remove the 3 screws and remove LDP pump.
INSTALLATION
(1) Install LDP.
(2) Install the 3 screws and tighten (Fig. 5).
(3) Install the electrical connector.
(4) Install the 3 hoses (Fig. 4).(5) Lower vehicle.
(6) Connect the negative battery cable.
Fig. 4 LDP LOCATION
Fig. 5 LDP REMOVAL/INSTALLATION
25 - 14 EVAPORATIVE EMISSIONSRS
LEAK DETECTION PUMP (Continued)
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ORVR
OPERATION
The emission control principle used in the ORVR sys-
tem is that the fuel flowing into the filler tube (appx. 1º
I.D.) creates an aspiration effect which draws air into
the fill tube (Fig. 6). During refueling, the fuel tank is
vented to the vapor canister to capture escaping vapors.
With air flowing into the filler tube, there are no fuel
vapors escaping to the atmosphere. Once the refueling
vapors are captured by the canister, the vehicle's com-
puter controlled purge system draws vapor out of the
canister for the engine to burn. The vapors flow is
metered by the purge solenoid so that there is no or
minimal impact on driveability or tailpipe emissions.
As fuel starts to flow through the fill tube, it opens
the normally closed check valve and enters the fuel
tank. Vapor or air is expelled from the tank through the
control valve to the vapor canister. Vapor is absorbed in
the canister until vapor flow in the lines stops, either
following shut-off or by having the fuel level in the tank
rise high enough to close the control valve. The controlvalve(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/
FUEL TANK - OPERATION) contains a float that rises
to seal the large diameter vent path to the canister. At
this point in the fueling of the vehicle, the tank pres-
sure increases, the check valve closes (preventing tank
fuel from spiting back at the operator), and fuel then
rises up the filler tube to shut-off the dispensing nozzle.
If the engine is shut-off while the On-Board diagnos-
tics test is running, low level tank pressure can be
trapped in the fuel tank and fuel can not be added to
the tank until the pressure is relieved. This is due to
the leak detection pump closing the vapor outlet from
the top of the tank and the one-way check valve not
allowing the tank to vent through the fill tube to atmo-
sphere. Therefore, when fuel is added, it will back-up in
the fill tube and shut off the dispensing nozzle. The
pressure can be eliminated in two ways: 1. Vehicle
purge must be activated and for a long enough period to
eliminate the pressure. 2. Removing the fuel cap and
allowing enough time for the system to vent thru the
recirulation tube.
Fig. 6 ORVR System Schematic
1 - FUEL CAP
2 - RECIRCULATION TUBE
3 - LIQUID SEPARATOR
4 - PURGE
5 - W/LDP
6 - BREATHER ELEMENT
7 - W/O LDP8 - CANISTER
9 - ROLLOVER VALVE
10 - FUEL TANK
11 - CHECK VALVE
12 - CONTROL VALVE
RSEVAPORATIVE EMISSIONS25-15
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DIAGNOSIS AND TESTING - VEHICLE DOES
NOT FILL
CONDITION POSSIBLE CAUSES CORRECTION
Pre-Mature Nozzle Shut-Off Defective fuel tank assembly
components.Fill tube improperly installed
(sump)
Fill tube hose pinched.
Check valve stuck shut.
Control valve stuck shut.
Defective vapor/vent components. Vent line from control valve to
canister pinched.
Vent line from canister to vent
filter pinched.
Canister vent valve failure
(requires double failure,
plugged to LDP and
atmosphere).
Leak detection pump failed
closed.
Leak detection pump filter
plugged.
On-Board diagnostics evaporative
system leak test just conducted.Canister vent valve vent
plugged to atmosphere.
engine still running when
attempting to fill (System
designed not to fill).
Defective fill nozzle. Try another nozzle.
Fuel Spits Out Of Filler
Tube.During fill. See Pre-Mature Shut-Off.
At conclusion of fill. Defective fuel handling
component. (Check valve stuck
open).
Defective vapor/vent handling
component.
Defective fill nozzle.
25 - 16 EVAPORATIVE EMISSIONSRS
ORVR (Continued)
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PCV VALVE
DESCRIPTION
The PCV valve contains a spring loaded plunger.
The plunger meters the amount of crankcase vapors
routed into the combustion chamber based on intake
manifold vacuum.
OPERATION
When the engine is not operating or during an
engine backfire, the spring forces the plunger back
against the seat. This prevents vapors from flowing
through the valve (Fig. 8).
When the engine is at idle or cruising, high mani-
fold vacuum is present. At these times manifold vac-
uum is able to completely compress the spring and
pull the plunger to the top of the valve (Fig. 9). In
this position there is minimal vapor flow through the
valve.During periods of moderate intake manifold vac-
uum the plunger is only pulled part way back from
the inlet. This results in maximum vapor flow
through the valve (Fig. 10).
DIAGNOSIS AND TESTING - PCV SYSTEM
INSPECTION
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE PERFORMING ANY TEST
OR ADJUSTMENT WITH THE ENGINE OPERATING.
(1) With engine idling, remove the hose from the
PCV valve. If the valve is not plugged, a hissing
noise will be heard as air passes through the valve. A
strong vacuum should also be felt when a finger is
placed over the valve inlet.
(2) Install hose on PCV valve. Remove the
make-up air hose from the air plenum at the rear of
the engine. Hold a piece of stiff paper (parts tag)
loosely over the end of the make-up air hose.
(3)
After allowing approximately one minute for
crankcase pressure to reduce, the paper should draw up
against the hose with noticeable force. If the engine
does not draw the paper against the grommet after
installing a new valve, replace the PCV valve hose.
(4)Turn the engine off. Remove the PCV valve from
intake manifold. The valve should rattle when shaken.
(5) Replace the PCV valve and retest the system if
it does not operate as described in the preceding
tests.Do not attempt to clean the old PCV valve.
If the valve rattles, apply a light coating of Loctitet
Pipe Sealant With Teflon to the threads. Thread the
PCV valve into the manifold plenum and tighten to 7
N´m (60 in. lbs.) torque.
Fig. 7 PCV VALVE 2.4L
1 - PCV Valve
Fig. 8 Engine Off or Engine Backfire No Vapor Flow
Fig. 9 High Intake Manifold Vacuum Minimal Vapor
Flow
Fig. 10 Moderate Intake Manifold Vacuum Maximum
Vapor Flow
RSEVAPORATIVE EMISSIONS25-17
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VAPOR CANISTER
DESCRIPTION
There are 2 EVAP canisters on the vehicle. The vac-
uum and vapor tubes connect to the top of the canister.
It is a charcoal canister (Fig. 11) or (Fig. 12).
OPERATION
All vehicles use a, maintenance free, evaporative
(EVAP) canister. Fuel tank vapors vent into the can-
ister. The canister temporarily holds the fuel vapors
until intake manifold vacuum draws them into the
combustion chamber. The Powertrain Control Module
(PCM) purges the canister through the proportional
purge solenoid. The PCM purges the canister at pre-
determined intervals and engine conditions.
Purge Free Cells
Purge-free memory cells are used to identify the
fuel vapor content of the evaporative canister. Since
the evaporative canister is not purged 100% of thetime, the PCM stores information about the evapora-
tive canister's vapor content in a memory cell.
The purge-free cells are constructed similar to cer-
tain purge-normal cells. The purge-free cells can be
monitored by the DRB IIItScan Tool. The only dif-
ference between the purge-free cells and normal
adaptive cells is that in purge-free, the purge is com-
pletely turned off. This gives the PCM the ability to
compare purge and purge-free operation.
REMOVAL
(1) Raise and support the vehicle.
(2) Remove the 2 hoses (Fig. 11).
(3) Remove bolt.
(4) Pull canister rearward to remove.
REMOVAL - REAR EVAP CANISTER
(1) Raise and support the vehicle.
(2) Remove 3 hoses (Fig. 12).
(3) Remove the bolt.
(4) Pull rearward to remove canister.
Fig. 11 FRONT EVAP CANISTER
1 - Front EVAP Canister
2 - Vent Valve
Fig. 12 REAR EVAP CANISTER
1 - Rear EVAP Canister
2 - Front EVAP Canister
3 - Vent Valve
25 - 18 EVAPORATIVE EMISSIONSRS
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NOTE: If you have a striped bolt at the Intake man-
ifold (Refer to 9 - ENGINE - STANDARD PROCE-
DURE) for thread repair.
INSTALLATION - 3.8L
(1) Loose install EGR tube and gasket with attach-
ing bolts at intake manifold.
(2) Loose install EGR tube and gasket with attach-
ing bolts at EGR valve.
(3) Tighten bolts to EGR valve to 11.9 N´m (105
620 ins. lbs.).
(4) Tighten bolts to Intake manifold to 11.9 N´m
(105620 ins. lbs.).
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. 3). 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 VALVE AND TUBE 2.4L
Fig. 2 EGR VALVE AND TUBE 3.3/3.8L
RSEXHAUST GAS RECIRCULATION25-21
TUBE (Continued)
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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.
REMOVAL - 3.3/3.8L
The EGR valve and Electrical EGR Transducer are
serviced as an assembly (Fig. 2).
(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 (200625 in. lbs.) torque.
(5) Tighten bolts from EGR valve to EGR tube to
11.9 N´m (105620 in. lbs.) torque.
(6) Reconnect vacuum hose and electrical connec-
tor to electrical EGR transducer.
INSTALLATION - 3.3/3.8L
The EGR valve and Electrical EGR Transducer are
serviced as an assembly (Fig. 2).
(1) Loose assemble the bolts from EGR valve to
EGR tube.
(2) Loose assemble the bolts from EGR valve to
cylinder head adaptor.
(3) Tighten bolts from EGR valve to EGR tube to
11.9 N´m (105620 in. lbs.) torque.
(4) Tighten bolts from EGR valve to cylinder head
to 22.9 N´m (200625 in. lbs.) torque.
(5) Reconnect vacuum hose and electrical connec-
tor to electrical EGR transducer.
Fig. 3 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
VALVE (Continued)
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The Task Manager Screen shows both a Requested
MIL state and an Actual MIL state. When the MIL is
illuminated upon completion of a test for a third trip,
the Requested MIL state changes to OFF. However,
the MIL remains illuminated until the next key
cycle. (On some vehicles, the MIL will actually turn
OFF during the third key cycle) During the key cycle
for the third good trip, the Requested MIL state is
OFF, while the Actual MILL state is ON. After the
next key cycle, the MIL is not illuminated and both
MIL states read OFF.
Diagnostic Trouble Codes (DTCs)
With OBD II, different DTC faults have different
priorities according to regulations. As a result, the
priorities determine MIL illumination and DTC era-
sure. DTCs are entered according to individual prior-
ity. DTCs with a higher priority overwrite lower
priority DTCs.
Priorities
²Priority 0 ÐNon-emissions related trouble codes
²Priority 1 Ð One trip failure of a two trip fault
for non-fuel system and non-misfire.
²Priority 2 Ð One trip failure of a two trip fault
for fuel system (rich/lean) or misfire.
²Priority3ÐTwotrip failure for a non-fuel sys-
tem and non-misfire or matured one trip comprehen-
sive component fault.
²Priority4ÐTwotrip failure or matured fault
for fuel system (rich/lean) and misfire or one trip cat-
alyst damaging misfire.
Non-emissions related failures have no priority.
One trip failures of two trip faults have low priority.
Two trip failures or matured faults have higher pri-
ority. One and two trip failures of fuel system and
misfire monitor take precedence over non-fuel system
and non-misfire failures.
DTC Self Erasure
With one trip components or systems, the MIL is
illuminated upon test failure and DTCs are stored.
Two trip monitors are components requiring failure
in two consecutive trips for MIL illumination. Upon
failure of the first test, the Task Manager enters a
maturing code. If the component fails the test for a
second time the code matures and a DTC is set.
After three good trips the MIL is extinguished and
the Task Manager automatically switches the trip
counter to a warm-up cycle counter. DTCs are auto-
matically erased following 40 warm-up cycles if the
component does not fail again.
For misfire and fuel system monitors, the compo-
nent must pass the test under a Similar Conditions
Window in order to record a good trip. A Similar Con-
ditions Window is when engine RPM is within6375RPM and load is within610% of when the fault
occurred.
NOTE: It is important to understand that a compo-
nent does not have to fail under a similar window of
operation to mature. It must pass the test under a
Similar Conditions Window when it failed to record
a Good Trip for DTC erasure for misfire and fuel
system monitors.
DTCs can be erased anytime with a DRBIIIt.
Erasing the DTC with the DRBIIIterases all OBD II
information. The DRBIIItautomatically displays a
warning that erasing the DTC will also erase all
OBD II monitor data. This includes all counter infor-
mation for warm-up cycles, trips and Freeze Frame.
Trip Indicator
TheTripis essential for running monitors and
extinguishing the MIL. In OBD II terms, a trip is a
set of vehicle operating conditions that must be met
for a specific monitor to run. All trips begin with a
key cycle.
Good Trip
The Good Trip counters are as follows:
²Global Good Trip
²Fuel System Good Trip
²Misfire Good Trip
²Alternate Good Trip (appears as a Global Good
Trip on DRBIIIt)
²Comprehensive Components
²Major Monitor
²Warm-Up Cycles
Global Good Trip
To increment a Global Good Trip, the Oxygen sen-
sor and Catalyst efficiency monitors must have run
and passed.
Fuel System Good Trip
To count a good trip (three required) and turn off
the MIL, the following conditions must occur:
²Engine in closed loop
²Operating in Similar Conditions Window
²Short Term multiplied by Long Term less than
threshold
²Less than threshold for a predetermined time
If all of the previous criteria are met, the PCM will
count a good trip (three required) and turn off the
MIL.
Misfire Good Trip
If the following conditions are met the PCM will
count one good trip (three required) in order to turn
off the MIL:
²Operating in Similar Condition Window
²1000 engine revolutions with no misfire
Alternate Good Trip
Alternate Good Trips are used in place of Global
Good Trips for Comprehensive Components and
25 - 24 ON-BOARD DIAGNOSTICSRS
TASK MANAGER (Continued)
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