2002 JEEP LIBERTY Workshop Manual

Freeze Frame Data Storage
Once a failure occurs, the Task Manager records
several engine operating conditions and stores it in a
Freeze Frame. The Freeze Frame is considered one
frame of information taken by an on-board data
recorder. When a fault occurs, the PCM stores the
input data from various sensors so that technicians
can determine under what vehicle operating condi-
tions the failure occurred.
The data stored in Freeze Frame is usually
recorded when a system fails the first time for two
trip faults. Freeze Frame data will only be overwrit-
ten by a different fault with a higher priority.
CAUTION: Erasing DTCs, either with the DRB III or
by disconnecting the battery, also clears all Freeze
Frame data.
Similar Conditions Window
The Similar Conditions Window displays informa-
tion about engine operation during a monitor. Abso-
lute MAP (engine load) and Engine RPM are stored
in this window when a failure occurs. There are two
different Similar conditions Windows: Fuel System
and Misfire.
FUEL SYSTEM
²Fuel System Similar Conditions WindowÐ
An indicator that 'Absolute MAP When Fuel Sys Fail'
and 'RPM When Fuel Sys Failed' are all in the same
range when the failure occurred. Indicated by switch-
ing from 'NO' to 'YES'.
²Absolute MAP When Fuel Sys FailÐ The
stored MAP reading at the time of failure. Informs
the user at what engine load the failure occurred.
²Absolute MAPÐ A live reading of engine load
to aid the user in accessing the Similar Conditions
Window.
²RPM When Fuel Sys FailÐ The stored RPM
reading at the time of failure. Informs the user at
what engine RPM the failure occurred.
²Engine RPMÐ A live reading of engine RPM
to aid the user in accessing the Similar Conditions
Window.
²Adaptive Memory FactorÐ The PCM utilizes
both Short Term Compensation and Long Term Adap-
tive to calculate the Adaptive Memory Factor for
total fuel correction.
²Upstream O2S VoltsÐ A live reading of the
Oxygen Sensor to indicate its performance. For
example, stuck lean, stuck rich, etc.
²SCW Time in Window (Similar Conditions
Window Time in Window)Ð A timer used by thePCM that indicates that, after all Similar Conditions
have been met, if there has been enough good engine
running time in the SCW without failure detected.
This timer is used to increment a Good Trip.
²Fuel System Good Trip CounterÐATrip
Counter used to turn OFF the MIL for Fuel System
DTCs. To increment a Fuel System Good Trip, the
engine must be in the Similar Conditions Window,
Adaptive Memory Factor must be less than cali-
brated threshold and the Adaptive Memory Factor
must stay below that threshold for a calibrated
amount of time.
²Test Done This TripÐ Indicates that the
monitor has already been run and completed during
the current trip.
MISFIRE
²Same Misfire Warm-Up StateÐ Indicates if
the misfire occurred when the engine was warmed up
(above 160É F).
²In Similar Misfire WindowÐ An indicator
that 'Absolute MAP When Misfire Occurred' and
'RPM When Misfire Occurred' are all in the same
range when the failure occurred. Indicated by switch-
ing from 'NO' to 'YES'.
²Absolute MAP When Misfire OccurredÐ
The stored MAP reading at the time of failure.
Informs the user at what engine load the failure
occurred.
²Absolute MAPÐ A live reading of engine load
to aid the user in accessing the Similar Conditions
Window.
²RPM When Misfire OccurredÐ The stored
RPM reading at the time of failure. Informs the user
at what engine RPM the failure occurred.
²Engine RPMÐ A live reading of engine RPM
to aid the user in accessing the Similar Conditions
Window.
²Adaptive Memory FactorÐ The PCM utilizes
both Short Term Compensation and Long Term Adap-
tive to calculate the Adaptive Memory Factor for
total fuel correction.
²200 Rev CounterÐ Counts 0±100 720 degree
cycles.
²SCW Cat 200 Rev CounterÐ Counts when in
similar conditions.
²SCW FTP 1000 Rev CounterÐ Counts 0±4
when in similar conditions.
²Misfire Good Trip CounterÐ Counts up to
three to turn OFF the MIL.
²Misfire DataÐ Data collected during test.
²Test Done This TripÐ Indicates YES when the
test is done.
KJEMISSIONS CONTROL 25 - 23
EMISSIONS CONTROL (Continued)

EVAPORATIVE EMISSIONS
TABLE OF CONTENTS
page page
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAPORATION CONTROL
SYSTEM............................24
SPECIFICATIONS
TORQUE............................26
EVAP/PURGE SOLENOID
DESCRIPTION.........................27
OPERATION...........................27
REMOVAL.............................27
INSTALLATION.........................27
FUEL FILLER CAP
DESCRIPTION.........................27
OPERATION...........................27
LEAK DETECTION PUMP
DESCRIPTION.........................27
OPERATION...........................28
REMOVAL.............................28INSTALLATION.........................28
ORVR
DESCRIPTION.........................29
OPERATION...........................29
P C V VA LV E
DESCRIPTION.........................29
OPERATION...........................31
DIAGNOSIS AND TESTING - PCV VALVE.....31
REMOVAL.............................32
INSTALLATION.........................32
VACUUM LINES
DESCRIPTION.........................33
VAPOR CANISTER
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
EVAPORATIVE EMISSIONS
DESCRIPTION - EVAPORATION CONTROL
SYSTEM
The evaporation control system prevents the emis-
sion of fuel tank vapors into the atmosphere. When
fuel evaporates in the fuel tank, the vapors pass
through the control valve located in the top section of
the fuel pump module, through the fuel management
valve, and through vent hoses and tubes to a char-
coal filled evaporative canister. The canister tempo-
rarily holds the vapors. The Powertrain Control
Module (PCM) allows intake manifold vacuum to
draw vapors into the combustion chambers during
certain operating conditions.
Gas powered engines use a duty cycle purge sys-
tem. The PCM controls vapor flow by operating theduty cycle EVAP purge solenoid. Refer to Duty Cycle
EVAP Canister Purge Solenoid.
When equipped with certain emissions packages, a
Leak Detection Pump (LDP) will be used as part of
the evaporative system for OBD II requirements.
Also refer to Leak Detection Pump.
Vehicles powered with gasoline engines are also
equipped with ORVR (On-Board Refueling Vapor
Recovery). Refer to ORVR for additional information.
NOTE: The evaporative system uses specially man-
ufactured lines/hoses. If replacement becomes nec-
essary, only use fuel resistant, low permeation
hose.
Certain components can be found in (Fig. 1).
25 - 24 EVAPORATIVE EMISSIONSKJ

Fig. 1 FUEL DELIVERY COMPONENTS
1 - FUEL TANK 10 - EVAP CANISTER
2 - FUEL TANK STRAPS 11 - FLOW MANAGEMENT VALVE
3 - FUEL PUMP MODULE LOCK RING 12 - FRESH AIR TUBE
4 - CHECK (CONTROL) VALVE 13 - HOSE SLEEVE
5 - FUEL PUMP MODULE FLANGE 14 - FUEL FILTER
6 - FUEL FILL HOSE 15 - LEAK DETECTION PUMP
7 - FRESH AIR FILTER 16 - HEAT SHIELD
8 - FUEL FILL CAP/BEZEL 17 - SKID PLATE
9 - FUEL FILL TUBE
KJEVAPORATIVE EMISSIONS 25 - 25
EVAPORATIVE EMISSIONS (Continued)

SPECIFICATIONS
TORQUE
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Accelerator Pedal Bracket
Mounting Nuts12 - 105
Crankshaft Position Sensor - 2.4L 28 21 -
Crankshaft Position Sensor - 3.7L 28 21 -
Camshaft Position Sensor - 2.4L 12 - 106
Camshaft Position Sensor - 3.7L 12 - 106
Engine Coolant Temperature
Sensor11 - 9 6
EVAP Canister-to-Body Bolts 48 35 -
EVAP Canister-to-Canis. Bracket
Bolt/Nut11 - 100
Fuel Filler Hose Clamp at Tank 3 - 30
Fuel Filler Housing-to-Body
Screws2-17
Fuel Filter Mounting Nut at Tank 5.5 - 49
Fuel Pump Module Access Plate
Nuts3-26
Fuel Rail Mounting Bolts - 3.7L 11 - 100
Fuel Rail Mounting Bolts - 2.4L 28 - 250
Fuel Tank Heat Sheild Nuts 5.5 - 49
Fuel Tank Mounting Strap Bolts 61 45 -
Fuel Tank Skid Plate and Trailer
Hitch88 65 -
IAC Motor Mounting Screws 7 - 60
Leak Detection Pump Mounting
Bracket-to-Fuel Tank Nuts5.5 - 49
Leak Detection Pump-to-Bracket
Nuts1.2 - 11
Map Sensor Mounting Screws 3 - 25
PCM-to-Mounting Bracket
Mounting Screws4-35
Power Steering Pressure Switch 14-22 - 124-195
TPS Mounting Screws 7 - 60
Throttle Body Mounting Bolts 11 - 100
Oxygen Sensors 30 22 -
25 - 26 EVAPORATIVE EMISSIONSKJ
EVAPORATIVE EMISSIONS (Continued)

EVAP/PURGE SOLENOID
DESCRIPTION
The duty cycle EVAP canister purge solenoid (DCP)
is located in the engine compartment. It is attached
to a bracket located between the battery and the
Power Distribution Center (PDC). The EVAP system
test port is located near the solenoid.
OPERATION
The duty cycle EVAP canister purge solenoid (DCP)
regulates the rate of vapor flow from the EVAP can-
ister to the intake manifold. The Powertrain Control
Module (PCM) operates the solenoid.
During the cold start warm-up period and the hot
start time delay, the PCM does not energize the sole-
noid. When de-energized, no vapors are purged. The
PCM de-energizes the solenoid during open loop oper-
ation.
The engine enters closed loop operation after it
reaches a specified temperature and the time delay
ends. During closed loop operation, the PCM cycles
(energizes and de-energizes) the solenoid 5 or 10
times per second, depending upon operating condi-
tions. The PCM varies the vapor flow rate by chang-
ing solenoid pulse width. Pulse width is the amount
of time that the solenoid is energized. The PCM
adjusts solenoid pulse width based on engine operat-
ing condition.
REMOVAL
The duty cycle EVAP canister purge solenoid (DCP)
is located in the engine compartment (Fig. 2). It is
attached to a bracket located between the battery
and the Power Distribution Center (PDC). The EVAP
system test port is located near the solenoid (Fig. 2).
(1) Disconnect electrical wiring connector at sole-
noid.
(2) Disconnect vacuum harness at solenoid.
(3) Remove solenoid and its support bracket (pull
straight up).
INSTALLATION
(1) Slip EVAP canister purge solenoid onto its
mounting bracket.
(2) Connect vacuum harness to solenoid.
(3) Connect electrical connector to solenoid.
FUEL FILLER CAP
DESCRIPTION
The plastic fuel tank filler tube cap is threaded
onto the end of the fuel fill tube. All models are
equipped with a 1/4 turn cap.
OPERATION
The loss of any fuel or vapor out of fuel filler tube
is prevented by the use of a pressure-vacuum fuel fill
cap. Relief valves inside the cap will release fuel tank
pressure at predetermined pressures. Fuel tank vac-
uum will also be released at predetermined values.
This cap must be replaced by a similar unit if
replacement is necessary. This is in order for the sys-
tem to remain effective.
CAUTION: Remove fill cap before servicing any fuel
system component to relieve tank pressure. If
equipped with an ORVR system and a Leak Detec-
tion Pump (LDP), the cap must be tightened
securely. If cap is left loose, a Diagnostic Trouble
Code (DTC) may be set.
LEAK DETECTION PUMP
DESCRIPTION
The Leak Detection Pump (LDP) is bolted to the
front of the fuel tank (Fig. 1).
The Leak Detection Pump (LDP) is used only with
certain emission packages.
The LDP is a device used to detect a leak in the
evaporative system.
Fig. 2 EVAP / PURGE SOLENOID LOCATION
1 - BATTERY
2 - EVAP/PURGE SOLENOID LOCATION
3 - MOUNTING BRACKET
4 - POWER DISTRIBUTION CENTER (PDC)
5 - SOLENOID ELECTRICAL CONNECTOR
6 - EVAP SYSTEM TEST PORT
KJEVAPORATIVE EMISSIONS 25 - 27

The pump contains a 3 port solenoid, a pump that
contains a switch, a spring loaded canister vent valve
seal, 2 check valves and a spring/diaphragm.
OPERATION
Immediately after a cold start, engine temperature
between 40ÉF and 86ÉF, the 3 port solenoid is briefly
energized. This initializes the pump by drawing air
into the pump cavity and also closes the vent seal.
During non-test test conditions, the vent seal is held
open by the pump diaphragm assembly which pushes
it open at the full travel position. The vent seal will
remain closed while the pump is cycling. This is due
to the operation of the 3 port solenoid which prevents
the diaphragm assembly from reaching full travel.
After the brief initialization period, the solenoid is
de-energized, allowing atmospheric pressure to enter
the pump cavity. This permits the spring to drive the
diaphragm which forces air out of the pump cavity
and into the vent system. When the solenoid is ener-
gized and de-energized, the cycle is repeated creating
flow in typical diaphragm pump fashion. The pump
is controlled in 2 modes:
PUMP MODE:The pump is cycled at a fixed rate
to achieve a rapid pressure build in order to shorten
the overall test time.
TEST MODE:The solenoid is energized with a
fixed duration pulse. Subsequent fixed pulses occur
when the diaphragm reaches the switch closure
point.
The spring in the pump is set so that the system
will achieve an equalized pressure of about 7.5 inches
of water.
When the pump starts, the cycle rate is quite high.
As the system becomes pressurized pump rate drops.
If there is no leak the pump will quit. If there is a
leak, the test is terminated at the end of the test
mode.
If there is no leak, the purge monitor is run. If the
cycle rate increases due to the flow through the
purge system, the test is passed and the diagnostic is
complete.
The canister vent valve will unseal the system
after completion of the test sequence as the pump
diaphragm assembly moves to the full travel position.
REMOVAL
The Leak Detection Pump (LDP) is attached (bolt-
ed) to the front of the fuel tank (Fig. 3). The LDP
fresh air filter is located on the end of a hose. This
hose is attached to the fuel fill tube assembly below
and near the fuel fill opening (Fig. 1). The LDP and
LDP filter are typically replaced (serviced) as one
unit.
(1) Raise vehicle.(2) Carefully remove two 3/4º vent hoses at sides
of LDP.
(3) Carefully remove other vapor/vacuum hoses
from LDP.
(4) Place a hydraulic jack under fuel tank.
(5) Loosen 2 fuel tank strap mounting bolts at
front of tank about 10 turns.
(6) Lower front of fuel tank about 1/2º.
(7) Remove 2 LDP mounting nuts (Fig. 3) and
lower LDP slightly to gain access to electrical connec-
tor (Fig. 4).
(8) Disconnect electrical connector at LDP. To dis-
connect: Slide red colored tab upward. Push on black
colored tab while removing connector.
(9) Remove LDP from vehicle.
INSTALLATION
The Leak Detection Pump (LDP) is attached (bolt-
ed) to the front of the fuel tank. The LDP filter is
located on the end of a hose. This hose is attached to
the fuel fill tube assembly below and near the fuel
fill opening. The LDP and LDP filter are replaced
(serviced) as one unit.
(1) Install electrical connector to LDP. Push red
colored tab downward to lock connector to LDP.
(2) Position LDP and LDP bracket to fuel tank
mounting studs and install 2 nuts. Tighten nuts to 1
N´m (11 in. lbs.) torque.
(3) Raise fuel tank to body and tighten 2 strap
bolts to 61 N´m (45 ft. lbs.) torque.
Fig. 3 LDP LOCATION / MOUNTING
1 - LDP
2 - FLOW MANAGEMENT VALVE
3 - MOUNTING NUTS
4 - FRONT OF FUEL TANK
25 - 28 EVAPORATIVE EMISSIONSKJ
LEAK DETECTION PUMP (Continued)

(4) Carefully install vapor/vacuum lines to LDP,
and install hose to LDP filter.The vapor/vacuum
lines and hoses must be firmly connected.
Check the vapor/vacuum lines at the LDP, LDP
filter and EVAP canister duty cycle purge sole-
noid for damage or leaks. If a leak is present, a
Diagnostic Trouble Code (DTC) may be set.
ORVR
DESCRIPTION
The ORVR (On-Board Refueling Vapor Recovery)
system consists of a unique fuel tank, flow manage-
ment valve, fluid control valve, one-way check valve
and vapor canister (Fig. 1).
OPERATION
The ORVR (On-Board Refueling Vapor Recovery)
system is used to remove excess fuel tank vapors.
This is done while the vehicle is being refueled. Cer-
tain ORVR components can be found in (Fig. 1).
Fuel flowing into the fuel filler tube (approx. 1º
I.D.) creates an aspiration effect drawing air into the
fuel fill tube. During refueling, the fuel tank is
vented to the EVAP 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 EVAP canister,the vehicle's computer controlled purge system draws
vapor out of the canister for the engine to burn. The
vapor 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 fuel 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 and on to the vapor canis-
ter. Vapor is absorbed in the EVAP canister until
vapor flow in the lines stops. This stoppage occurs
following fuel shut-off, or by having the fuel level in
the tank rise high enough to close the control valve.
This control valve contains a float that rises to seal
the large diameter vent path to the EVAP canister.
At this point in the refueling process, fuel tank pres-
sure increases, the check valve closes (preventing liq-
uid fuel from spiting back at the operator), and fuel
then rises up the fuel filler tube to shut off the dis-
pensing nozzle.
PCV VALVE
DESCRIPTION
2.4L
The 2.4L 4-cylinder engine is equipped with a
closed crankcase ventilation system and a Positive
Crankcase Ventilation (PCV) valve.
This system consists of:
²a PCV valve attached to the left/front side of the
valve cover (Fig. 5). It is secured with 1 bolt. An
o-ring is used to seal valve to valve cover (Fig. 6).
²the air cleaner housing
²tubes and hoses to connect the system compo-
nents.
3.7L
The 3.7L V-6 engine is equipped with a closed
crankcase ventilation system and a Positive Crank-
case Ventilation (PCV) valve.
This system consists of:
²a PCV valve mounted to the oil filler housing
(Fig. 7). The PCV valve is sealed to the oil filler
housing with an o-ring.
²the air cleaner housing
²two interconnected breathers threaded into the
rear of each cylinder head (Fig. 8).
²tubes and hoses to connect the system compo-
nents.
Fig. 4 LDP ELECTRICAL CONNECTOR
1 - LEAK DETECTION PUMP (LDP)
2 - ELECTRICAL CONNECTOR
3 - FUEL FILTER
KJEVAPORATIVE EMISSIONS 25 - 29
LEAK DETECTION PUMP (Continued)

Fig. 5 PCV VALVE LOCATION - 2.4L
1 - P C V VA LV E
2 - HOSE
3 - MOUNTING BOLT
4 - VALVE COVER (LEFT SIDE)
Fig. 6 PCV VALVE AND O-RING - 2.4L
1 - P C V VA LV E
2 - O-RING
3 - MOUNTING BOLT
Fig. 7 PCV VALVE - 3.7L
1 - O-RING
2 - LOCATING TABS
3 - CAM LOCK
4 - OIL FILLER TUBE
5 - PCV LINE/HOSE
6 - P C V VA LV E
Fig. 8 CRANKCASE BREATHERS (2) - 3.7L
1 - CRANKCASE BREATHERS (2)
2 - REAR OF ENGINE
25 - 30 EVAPORATIVE EMISSIONSKJ
PCV VALVE (Continued)