3.7 v6 JEEP LIBERTY 2002 KJ / 1.G Workshop Manual

INSTALLATION
2.4L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the rear of the intake manifold. An
o-ring is used to seal the sensor to the intake mani-
fold (Fig. 19).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Install MAP sensor mounting screws. Tighten
screw to 3 N´m (25 in. lbs.) torque.
(5) Connect electrical connector.
3.7L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold (Fig.
18). An o-ring is used to seal the sensor to the intake
manifold (Fig. 19).
(1) Clean MAP sensor mounting hole at intake
manifold.
(2) Check MAP sensor o-ring seal for cuts or tears.
(3) Position sensor into manifold.
(4) Install MAP sensor mounting bolts (screws).
Tighten screws to 3 N´m (25 in. lbs.) torque.
(5) Connect electrical connector.
OXYGEN SENSOR
DESCRIPTION
The Oxygen Sensors (O2S) are attached to, and
protrude into the vehicle exhaust system. Depending
on the engine or emission package, the vehicle may
use a total of either 2 or 4 sensors.
2.4L Engine:Two sensors are used: upstream
(referred to as 1/1) and downstream (referred to as
1/2). With this emission package, the upstream sen-
sor (1/1) is located just before the main catalytic con-
vertor. The downstream sensor (1/2) is located just
after the main catalytic convertor.
3.7L V-6 Engine:On this emissions package, 4
sensors are used: 2 upstream (referred to as 1/1 and
2/1) and 2 downstream (referred to as 1/2 and 2/2).
With this emission package, the right upstream sen-
sor (2/1) is located in the right exhaust downpipe just
before the mini-catalytic convertor. The left upstream
sensor (1/1) is located in the left exhaust downpipe
just before the mini-catalytic convertor. The right
downstream sensor (2/2) is located in the right
exhaust downpipe just after the mini-catalytic con-
vertor, and before the main catalytic convertor. The
left downstream sensor (1/2) is located in the left
exhaust downpipe just after the mini-catalytic con-
vertor, and before the main catalytic convertor.
OPERATION
An O2 sensor is a galvanic battery that provides
the PCM with a voltage signal (0-1 volt) inversely
proportional to the amount of oxygen in the exhaust.
In other words, if the oxygen content is low, the volt-
age output is high; if the oxygen content is high the
output voltage is low. The PCM uses this information
to adjust injector pulse-width to achieve the
14.7±to±1 air/fuel ratio necessary for proper engine
operation and to control emissions.
The O2 sensor must have a source of oxygen from
outside of the exhaust stream for comparison. Cur-
rent O2 sensors receive their fresh oxygen (outside
air) supply through the O2 sensor case housing.
Four wires (circuits) are used on each O2 sensor: a
12±volt feed circuit for the sensor heating element; a
ground circuit for the heater element; a low-noise
sensor return circuit to the PCM, and an input cir-
cuit from the sensor back to the PCM to detect sen-
sor operation.
Oxygen Sensor Heater Relay - 3.7L Engine:On
the 3.7L engine, 4 heated oxygen sensors are used. A
separate oxygen sensor relay is used to supply volt-
age to the sensors heating elements for only the 1/2
and 2/2 downstream sensors. Voltage for the other 2
sensor heating elements is supplied directly from the
Powertrain Control Module (PCM) through a Pulse
Width Module (PWM) method.
Pulse Width Module (PWM):Voltage to the O2
sensor heating elements is supplied directly from the
Powertrain Control Module (PCM) through two sepa-
rate Pulse Width Module (PWM) low side drivers.
PWM is used on both the upstream and downstream
O2 sensors on the 2.4L engine, and only on the 2
upstream sensors (1/1 and 2/1) on the 3.7L engine.
The main objective for a PWM driver is to avoid over-
heating of the O2 sensor heater element. With
exhaust temperatures increasing with time and
engine speed, it's not required to have a full-voltage
duty-cycle on the O2 heater elements.
To avoid the large simultaneous current surge
needed to operate all 4 sensors, power is delayed to
the 2 downstream heater elements by the PCM for
approximately 2 seconds.
Oxygen Sensor Heater Elements:
The O2 sensor uses a Positive Thermal Co-efficient
(PTC) heater element. As temperature increases,
resistance increases. At ambient temperatures
around 70ÉF, the resistance of the heating element is
approximately 4.5 ohms. As the sensor's temperature
increases, resistance in the heater element increases.
This allows the heater to maintain the optimum
operating temperature of approximately 930É-1100ÉF
(500É-600É C). Although the sensors operate the
same, there are physical differences, due to the envi-
14 - 40 FUEL INJECTIONKJ
MAP SENSOR (Continued)

ronment that they operate in, that keep them from
being interchangeable.
Maintaining correct sensor temperature at all
times allows the system to enter into closed loop
operation sooner. Also, it allows the system to remain
in closed loop operation during periods of extended
idle.
In Closed Loop operation, the PCM monitors cer-
tain O2 sensor input(s) along with other inputs, and
adjusts the injector pulse width accordingly. During
Open Loop operation, the PCM ignores the O2 sensor
input. The PCM adjusts injector pulse width based
on preprogrammed (fixed) values and inputs from
other sensors.
Upstream Sensor - 2.4L Engine:The upstream
sensor (1/1) provides an input voltage to the PCM.
The input tells the PCM the oxygen content of the
exhaust gas. The PCM uses this information to fine
tune fuel delivery to maintain the correct oxygen con-
tent at the downstream oxygen sensor. The PCM will
change the air/fuel ratio until the upstream sensor
inputs a voltage that the PCM has determined will
make the downstream sensor output (oxygen content)
correct.
The upstream oxygen sensor also provides an input
to determine catalytic convertor efficiency.
Downstream Sensor - 2.4L Engine:The down-
stream oxygen sensor (1/2) is also used to determine
the correct air-fuel ratio. As the oxygen content
changes at the downstream sensor, the PCM calcu-
lates how much air-fuel ratio change is required. The
PCM then looks at the upstream oxygen sensor volt-
age and changes fuel delivery until the upstream
sensor voltage changes enough to correct the down-
stream sensor voltage (oxygen content).
The downstream oxygen sensor also provides an
input to determine catalytic convertor efficiency.
Upstream Sensors - 3.7L Engine:Two upstream
sensors are used (1/1 and 2/1). The 1/1 sensor is the
first sensor to receive exhaust gases from the #1 cyl-
inder. They provide an input voltage to the PCM. The
input tells the PCM the oxygen content of the
exhaust gas. The PCM uses this information to fine
tune fuel delivery to maintain the correct oxygen con-
tent at the downstream oxygen sensors. The PCM
will change the air/fuel ratio until the upstream sen-
sors input a voltage that the PCM has determined
will make the downstream sensors output (oxygen
content) correct.
The upstream oxygen sensors also provide an input
to determine mini-catalyst efficiency. Main catalytic
convertor efficiency is not calculated with this pack-
age.
Downstream Sensors - 3.7L Engine:Two down-
stream sensors are used (1/2 and 2/2). The down-
stream sensors are used to determine the correct air-fuel ratio. As the oxygen content changes at the
downstream sensor, the PCM calculates how much
air-fuel ratio change is required. The PCM then looks
at the upstream oxygen sensor voltage, and changes
fuel delivery until the upstream sensor voltage
changes enough to correct the downstream sensor
voltage (oxygen content).
The downstream oxygen sensors also provide an
input to determine mini-catalyst efficiency. Main cat-
alytic convertor efficiency is not calculated with this
package.
Engines equipped with either a downstream sen-
sor(s), or a post-catalytic sensor, will monitor cata-
lytic convertor efficiency. If efficiency is below
emission standards, the Malfunction Indicator Lamp
(MIL) will be illuminated and a Diagnostic Trouble
Code (DTC) will be set. Refer to Monitored Systems
in Emission Control Systems for additional informa-
tion.
REMOVAL
CAUTION: Never apply any type of grease to the
oxygen sensor electrical connector, or attempt any
soldering of the sensor wiring harness.
Refer to (Fig. 20), (Fig. 21) or (Fig. 22) for O2S
(oxygen sensor) location.
Fig. 20 OXYGEN SENSORS - 2.4L
1 - ELECTRICAL CONNECTORS
2 - UPSTREAM SENSOR (1/1)
3 - ELECTRICAL CONNECTORS
4 - DOWNSTREAM SENSOR (1/2)
KJFUEL INJECTION 14 - 41
OXYGEN SENSOR (Continued)

Fig. 21 OXYGEN SENSORS - UPSTREAM - 3.7L
1 - RIGHT UPSTREAM SENSOR (2/1)
2 - ELECTRICAL CONNECTORS3 - LEFT UPSTREAM SENSOR (1/1)
4 - ELECTRICAL CONNECTORS
Fig. 22 OXYGEN SENSORS - DOWNSTREAM - 3.7L
1 - ELECTRICAL CONNECTORS
2 - ELECTRICAL CONNECTORS3 - LEFT DOWNSTREAM SENSOR (1/2)
4 - RIGHT DOWNSTREAM SENSOR (2/2)
14 - 42 FUEL INJECTIONKJ
OXYGEN SENSOR (Continued)

WARNING: THE EXHAUST MANIFOLD, EXHAUST
PIPES AND CATALYTIC CONVERTER BECOME
VERY HOT DURING ENGINE OPERATION. ALLOW
ENGINE TO COOL BEFORE REMOVING OXYGEN
SENSOR.
(1) Raise and support vehicle.
(2) Disconnect wire connector from O2S sensor.
CAUTION: When disconnecting sensor electrical
connector, do not pull directly on wire going into
sensor.
(3) Remove O2S sensor with an oxygen sensor
removal and installation tool.
(4) Clean threads in exhaust pipe using appropri-
ate tap.
INSTALLATION
Threads of new oxygen sensors are factory coated
with anti-seize compound to aid in removal.DO
NOT add any additional anti-seize compound to
threads of a new oxygen sensor.
(1) Install O2S sensor. Tighten to 30 N´m (22 ft.
lbs.) torque.
(2) Connect O2S sensor wire connector.
(3) Lower vehicle.
THROTTLE BODY
DESCRIPTION
The throttle body is located on the intake manifold.
Fuel does not enter the intake manifold through the
throttle body. Fuel is sprayed into the manifold by
the fuel injectors.
OPERATION
Filtered air from the air cleaner enters the intake
manifold through the throttle body. The throttle body
contains an air control passage controlled by an Idle
Air Control (IAC) motor. The air control passage is
used to supply air for idle conditions. A throttle valve
(plate) is used to supply air for above idle conditions.
Certain sensors are attached to the throttle body.
The accelerator pedal cable, speed control cable and
transmission control cable (when equipped) are con-
nected to the throttle body linkage arm.
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the PCM.
REMOVAL
2.4L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section for removal/installation procedures.
(4) Disconnect necessary vacuum lines at throttle
body.
(5) Remove 3 throttle body mounting bolts (Fig.
23).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring.
3.7L
A (factory adjusted) set screw is used to mechani-
cally limit the position of the throttle body throttle
plate.Never attempt to adjust the engine idle
speed using this screw.All idle speed functions are
controlled by the Powertrain Control Module (PCM).
(1) Remove air cleaner tube at throttle body.
(2) Disconnect throttle body electrical connectors
at IAC motor and TPS.
Fig. 23 THROTTLE BODY MOUNTING BOLTS - 2.4L
1 - THROTTLE BODY
2 - IGNITION COIL
3 - MOUNTING BOLTS (3)
KJFUEL INJECTION 14 - 43
OXYGEN SENSOR (Continued)

(3) Remove all control cables from throttle body
(lever) arm. Refer to the Accelerator Pedal and Throt-
tle Cable section for removal/installation procedures.
(4) Disconnect necessary vacuum lines at throttle
body.
(5) Remove 3 throttle body mounting bolts (Fig.
24).
(6) Remove throttle body from intake manifold.
(7) Check condition of old throttle body-to-intake
manifold o-ring (Fig. 25).
INSTALLATION
2.4L
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N´m (105 in. lbs.) torque.
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air cleaner duct at throttle body.
3.7L
(1) Check condition of throttle body-to-intake man-
ifold o-ring. Replace as necessary.
(2) Clean mating surfaces of throttle body and
intake manifold.
(3) Install throttle body-to-intake manifold o-ring.
(4) Install throttle body to intake manifold.
(5) Install 3 mounting bolts. Tighten bolts to 12
N´m (105 in. lbs.) torque.
(6) Install control cables.
(7) Install electrical connectors.
(8) Install necessary vacuum lines.
(9) Install air cleaner duct at throttle body.
Fig. 24 THROTTLE BODY MOUNTING BOLTS - 3.7L
1 - THROTTLE BODY
2 - MOUNTING BOLTS (3)
Fig. 25 THROTTLE BODY O-RING - 3.7L
1 - INTAKE MANIFOLD
2 - THROTTLE BODY O-RING
14 - 44 FUEL INJECTIONKJ
THROTTLE BODY (Continued)

THROTTLE CONTROL CABLE
REMOVAL
2.4L
CAUTION: Be careful not to damage or kink the
cable core wire (within the cable sheathing) while
servicing accelerator pedal or throttle cable.
(1) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer (clip) and throttle cable
core wire from upper end of pedal arm (Fig. 26).
Plastic cable retainer snaps into top of pedal arm.
(2) Remove cable core wire at pedal arm.
(3) From inside vehicle, remove metal clip holding
cable to dashpanel (Fig. 26).
(4) Remove air box at throttle body.
(5) Unsnap cable from dashpanel routing clip.
(6) Remove cable housing from dash panel and
pull into engine compartment.
(7) Hold throttle in wide open position. While held
in this position, slide throttle cable pin (Fig. 27) from
throttle body bellcrank.(8) Using a pick or small screwdriver, press release
tab (Fig. 27) to release plastic cable mount from
bracket.Press on tab only enough to release
cable from bracket. If tab is pressed too much,
it will be broken.To remove throttle cable from
throttle body bracket, slide cable towards front of
vehicle.
(9) Remove throttle cable from vehicle.
3.7L
CAUTION: Be careful not to damage or kink the
cable core wire (within the cable sheathing) while
servicing accelerator pedal or throttle cable.
(1) From inside vehicle, hold up accelerator pedal.
Remove plastic cable retainer (clip) and throttle cable
core wire from upper end of pedal arm (Fig. 28).
Plastic cable retainer snaps into top of pedal arm.
(2) Remove cable core wire at pedal arm.
(3) From inside vehicle, remove metal clip holding
cable to dashpanel (Fig. 28).
(4) Remove air box at throttle body.
(5) Unsnap cable from dashpanel routing clip.
(6) Remove cable housing from dash panel and
pull into engine compartment.
(7) Hold throttle in wide open position. While held
in this position, slide throttle cable pin (Fig. 29) from
throttle body bellcrank.
Fig. 26 ACCELERATOR PEDAL/BRACKET
ASSEMBLY
1 - METAL THROTTLE CABLE CLIP
2 - THROTTLE CABLE
3 - PLASTIC CABLE RETAINER
4 - PEDAL/BRACKET ASSEMBLY
5 - PEDAL MOUNTING NUTS (2)
6 - PEDAL MOUNTING STUDS (2)
Fig. 27 THROTTLE CABLE, PIN, RELEASE TAB-2.4L
1 - MOUNTING BRACKET
2 - SPEED CONTROL CABLE
3 - THROTTLE CABLE
4 - RELEASE TAB
5 - CABLE PINS
6 - BELLCRANK
KJFUEL INJECTION 14 - 45

(8) Using a pick or small screwdriver, press release
tab (Fig. 30) to release plastic cable mount from
bracket.Press on tab only enough to release
cable from bracket. If tab is pressed too much,
it will be broken.Slide plastic mount (Fig. 30)
towards right side of vehicle to remove throttle cable
from throttle body bracket.
(9) Remove throttle cable from vehicle.
INSTALLATION
(1) Slide accelerator cable plastic mount into throt-
tle body mounting bracket. Continue sliding until
release tab (Fig. 30) is aligned to hole in mounting
bracket.
(2) Hold throttle in wide open position. While held
in this position, slide throttle cable pin (Fig. 29) into
throttle body bellcrank.
(3) Push cable housing into rubber grommet and
through opening in dash panel.
(4) From inside vehicle, install metal clip holding
cable to dashpanel (Fig. 28).
(5) From inside vehicle, slide throttle cable core
wire into opening (slot) in top of pedal arm.
(6) Push plastic cable retainer (clip) into pedal arm
opening until it snaps in place.
(7) Install air box to throttle body.
(8) Before starting engine, operate accelerator
pedal to check for any binding.
Fig. 28 ACCELERATOR PEDAL/BRACKET
ASSEMBLY
1 - METAL THROTTLE CABLE CLIP
2 - THROTTLE CABLE
3 - PLASTIC CABLE RETAINER
4 - PEDAL/BRACKET ASSEMBLY
5 - PEDAL MOUNTING NUTS (2)
6 - PEDAL MOUNTING STUDS (2)
Fig. 29 THROTTLE CABLE PIN-3.7L
1 - THROTTLE CABLE PIN
2 - THROTTLE BODY BELLCRANK
3 - PUSH UP HERE
Fig. 30 THROTTLE CABLE RELEASE TAB-3.7L
1 - THROTTLE CABLE
2 - RELEASE TAB
3 - PICK OR SCREWDRIVER
4 - PLASTIC CABLE MOUNT
14 - 46 FUEL INJECTIONKJ
THROTTLE CONTROL CABLE (Continued)

3.7L
The Throttle Position Sensor (TPS) is mounted to
the throttle body (Fig. 32), or (Fig. 33).
(1) Disconnect TPS electrical connector.
(2) Remove 2 TPS mounting screws.
(3) Remove TPS.
INSTALLATION
2.4L
The Throttle Position Sensor (TPS) is mounted to
the rear of the throttle body.
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 33). The TPS must be
installed so that it can be rotated a few degrees. (If
sensor will not rotate, install sensor with throttle
shaft on other side of socket tangs). The TPS will be
under slight tension when rotated.
(1) Install TPS and retaining screws.
(2) Tighten screws to 7 N´m (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.(4) Manually operate throttle (by hand) to check
for any TPS binding before starting engine.
(5) Install air cleaner tube to throttle body.
3.7L
The Throttle Position Sensor (TPS) is mounted to
the throttle body (Fig. 32).
The throttle shaft end of the throttle body slides
into a socket in the TPS (Fig. 33). The TPS must be
installed so that it can be rotated a few degrees. (If
sensor will not rotate, install sensor with throttle
shaft on other side of socket tangs). The TPS will be
under slight tension when rotated.
(1) Install TPS and retaining screws.
(2) Tighten screws to 7 N´m (60 in. lbs.) torque.
(3) Connect TPS electrical connector to TPS.
(4) Manually operate throttle (by hand) to check
for any TPS binding before starting engine.
(5) Install air cleaner tube to throttle body.
Fig. 32 TPS/IAC MOTOR - 3.7L
1 - THROTTLE POSITION SENSOR (TPS)
2 - MOUNTING SCREWS
3 - IDLE AIR CONTROL MOTOR (IAC)
4 - MOUNTING SCREWS
Fig. 33 TPS INSTALLATION - 3.7
1 - THROTTLE BODY
2 - TPS
3 - THROTTLE BODY SHAFT
4 - SOCKET LOCATING TANGS
14 - 48 FUEL INJECTIONKJ
THROTTLE POSITION SENSOR (Continued)

(13) Close valve fully three times and record high-
est pressure indicated each time.All three read-
ings must be above specifications and within
345 kPa (50 psi) of each other.
²Pressures above specifications but not within
345 kPa (50 psi) of each other, replace pump.
²Pressures within 345 kPa (50 psi) of each other
but below specifications, replace pump.
(14) Open the test valve and turn the steering
wheel to the extreme left and right positions three
times against the stops. Record the highest pressure
reading at each position. Compare readings to the
pump specifications chart. If pressures readings are
not within 50 psi of each other, the gear is leaking
internally and must be replaced.CAUTION: Do not force the pump to operate against
the stops for more than 2 to 3 seconds at a time
because, pump damage will result.
PUMP SPECIFICATION
ENGINERELIEF PRESSURE  
50FLOW RATE
(GPM) AT 1500
RPM
3.7L,
2.4L &
2.5L10342 kPa (1450 psi) 2.4 - 2.8
19 - 4 STEERINGKJ
STEERING (Continued)

PUMP
TABLE OF CONTENTS
page page
PUMP
DESCRIPTION.........................17
OPERATION...........................17
STANDARD PROCEDURE - POWER
STEERING PUMP - INITIAL OPERATION....18
REMOVAL
REMOVAL - 3.7L......................18
REMOVAL - 2.4L......................18
INSTALLATION
INSTALLATION - 3.7L..................19
INSTALLATION - 2.4L..................19
SPECIFICATIONS
TORQUE CHART......................19
SPECIAL TOOLS
POWER STEERING PUMP..............20
FLUID COOLER
DESCRIPTION.........................20
OPERATION...........................20
REMOVAL.............................20
INSTALLATION.........................20
HOSES
REMOVAL
REMOVAL - PRESSURE HOSE...........21
REMOVAL - RETURN HOSE (GEAR TO THE
COOLER)...........................21REMOVAL - RETURN HOSE (RESERVOIR
TO THE COOLER).....................21
INSTALLATION
INSTALLATION - PRESSURE HOSE.......21
INSTALLATION - RETURN HOSE (GEAR TO
THE COOLER)........................22
INSTALLATION - RETURN HOSE
(RESERVOIR TO THE COOLER)..........22
POWER STEERING PRESSURE SWITCH
DESCRIPTION.........................22
OPERATION...........................22
REMOVAL.............................22
INSTALLATION.........................22
PULLEY
REMOVAL.............................23
INSTALLATION.........................23
RESERVOIR
REMOVAL
REMOVAL - 3.7L......................24
REMOVAL - 2.4L......................24
INSTALLATION
INSTALLATION - 3.7L..................24
INSTALLATION - 2.4L..................24
PUMP
DESCRIPTION
Hydraulic pressure for the power steering system
is provided by a belt driven power steering pump
(Fig. 1). The pump shaft has a pressed-on high
strength plastic drive pulley that is belt driven by
the crankshaft pulley. The integral reservoir used on
the 3.7L only is attached to the pump body with
spring clips (Fig. 1). The 2.4L uses a remote fluid res-
ervoir (Fig. 2). The power steering pump is connected
to the steering gear by the pressure and return
hoses.
OPERATION
The power steering pump is a constant flow rate
and displacement, vane-type pump. The pump inter-
nal parts operate submerged in fluid. The flow con-
trol orifice is part of the high pressure line fitting.
The pressure relief valve inside the flow control valve
limits the pump pressure.Fig. 1 POWER STEERING PUMP ASSEMBLY
1 - RESERVOIR
2 - CAP
3 - PULLEY
4 - PUMP BODY
5 - RESERVOIR RETAINING CLIPS
KJPUMP 19 - 17