2002 JEEP LIBERTY air condition

CONDITION POSSIBLE CAUSES CORRECTION
OIL CONSUMPTION OR SPARK
PLUGS FOULED1. PCV system malfunction. 1. Check system and repair as
necessary. (Refer to 25 -
EMISSIONS CONTROL/
EVAPORATIVE EMISSIONS/PCV
VALVE - DIAGNOSIS AND
TESTING)
2. Worn, scuffed or broken rings. 2. Hone cylinder bores. Install new
rings.
3. Carbon in oil ring slots. 3. Install new rings.
4. Rings fitted too tightly in grooves. 4. Remove rings and check
grooves. If groove is not proper
width, replace piston.
5. Worn valve guide(s). 5. Replace cylinder head assembly.
6. Valve stem seal(s) worn or
damaged.6. Replace seal(s).
STANDARD PROCEDURE
STANDARD PROCEDURE - ENGINE CORE AND
OIL GALLERY PLUGS
Using a blunt tool such as a drift and a hammer,
strike the bottom edge of the cup plug. With the cup
plug rotated, grasp firmly with pliers or other suit-
able tool and remove plug (Fig. 2).
CAUTION: Do not drive cup plug into the casting as
restricted cooling can result and cause serious
engine problems.Thoroughly clean inside of cup plug hole in cylin-
der block or head. Be sure to remove old sealer.
Lightly coat inside of cup plug hole with Mopart
Stud and Bearing Mount. Make certain the new plug
is cleaned of all oil or grease. Using proper drive
plug, drive plug into hole so that the sharp edge of
the plug is at least 0.5 mm (0.020 in.) inside the
lead-in chamfer.
It is not necessary to wait for curing of the sealant.
The cooling system can be refilled and the vehicle
placed in service immediately.
STANDARD PROCEDURE - REPAIR OF
DAMAGED OR WORN THREADS
Damaged or worn threads (excluding spark plug
and camshaft bearing cap attaching threads) can be
repaired. Essentially, this repair consists of drilling
out worn or damaged threads, tapping the hole with
a special Heli-Coil Tap, (or equivalent) and installing
an insert into the tapped hole. This brings the hole
back to its original thread size.
CAUTION: Be sure that the tapped holes maintain
the original center line.
Heli-Coil tools and inserts are readily available
from automotive parts jobbers.
STANDARD PROCEDURE - HYDROSTATIC
LOCKED ENGINE
When an engine is suspected to be hydrostatically
locked, regardless of what caused the problem, the
following steps should be used.
CAUTION: DO NOT use starter motor to rotate the
engine, severe damage may occur.
Fig. 2 Core Hole Plug Removal
1 - CYLINDER BLOCK
2 - REMOVE PLUG WITH PLIERS
3 - STRIKE HERE WITH HAMMER
4 - DRIFT PUNCH
5 - CUP PLUG
KJENGINE9s-9
ENGINE - 2.4L (Continued)

INSPECTION
(1) Whenever valves have been removed for inspec-
tion, reconditioning or replacement, valve springs
should be tested for correct tension. Discard the
springs that do not meet specifications. The following
specifications apply to both intake and exhaust
valves springs:
²Valve Closed Nominal TensionÐ76 lbs. @ 38.0
mm (1.50 in.)
²Valve Open Nominal TensionÐ136 lbs. @ 29.75
mm (1.17 in.)
(2) Inspect each valve spring for squareness with a
steel square and surface plate, test springs from both
ends. If the spring is more than 1.5 mm (1/16 inch)
out of square, install a new spring.
INSTALLATION
INSTALLATION - CYLINDER HEAD ON
(1) Install valve seal/valve spring seat assembly
(Fig. 27). Push the assembly down to seat it onto the
valve guide.
(2) Install valve spring and retainer, use Special
Tool MD-998772-A with adapter 6779 to compress
valve springs only enough to install locks. Correct
alignment of tool is necessary to avoid nicking valve
stems.
(3) Remove air hose and install spark plugs.
(4) Install camshafts and cylinder head cover .
INSTALLATION - CYLINDER HEAD OFF
(1) Coat valve stems with clean engine oil and
insert in cylinder head.(2) Install new valve stem seals on all valves
using a valve stem seal tool (Fig. 28). The valve stem
seals should be pushed firmly and squarely over
valve guide.
CAUTION: When oversize valves are used, the cor-
responding oversize valve seal must also be used.
Excessive guide wear may result if oversize seals
are not used with oversize valves.
(3) Install valve springs and retainers. Compress
valve springs only enough to install locks, taking
care not to misalign the direction of compression.
Nicked valve stems may result from misalignment of
the valve spring compressor.
CAUTION: When depressing the valve spring retain-
ers with valve spring compressor the locks can
become dislocated. Ensure both locks are in the
correct location after removing tool.
(4) Check the valve spring installed height B after
refacing the valve and seat (Fig. 29). Make sure mea-
surements are taken from top of spring seat to the
bottom surface of spring retainer. If height is greater
than 38.75 mm (1.525 in.), install a 0.762 mm (0.030
in.) spacer under the valve spring seat to bring
spring height back within specification.
HYDRAULIC LIFTERS
DIAGNOSIS AND TESTING - LASH ADJUSTER
(TAPPET) NOISE DIAGNOSIS
A tappet-like noise may be produced from several
items. Check the following items.
(1) Engine oil level too high or too low. This may
cause aerated oil to enter the adjusters and cause
them to be spongy.
Fig. 27 Valve Stem Seal/Valve Spring Seat - Typical
1 - 3-GROOVE -VALVE RETAINING LOCKS
2 - VALVE SPRING
3 - VALVE SEAL AND VALVE SPRING SEAT ASSEMBLY
4 - VALVE SPRING RETAINER
Fig. 28 Valve Stem Oil Seal Tool
1 - VALVE SEAL TOOL
2 - VALVE STEM
9s - 28 ENGINEKJ
VALVE SPRINGS (Continued)

TIMING BELT AND
SPROCKET(S)
REMOVAL
REMOVAL - TIMING BELT
(1) Remove air cleaner upper cover, housing, and
clean air tube.
(2) Raise vehicle on hoist.
(3) Remove accessory drive belts. (Refer to 7 -
COOLING/ACCESSORY DRIVE/BELT TENSION-
ERS - REMOVAL)
(4) Remove crankshaft vibration damper. (Refer to
9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - REMOVAL)
(5) Remove air conditioner/generator belt tensioner
and pulley assembly. (Refer to 7 - COOLING/ACCES-
SORY DRIVE/BELT TENSIONERS - REMOVAL)
(6) Remove timing belt lower front cover bolts and
remove cover. (Refer to 9 - ENGINE/VALVE TIMING/
TIMING BELT / CHAIN COVER(S) - REMOVAL)
(7) Lower vehicle.
(8) Remove bolts attaching timing belt upper front
cover and remove cover. (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT / CHAIN COVER(S)
- REMOVAL)
CAUTION: When aligning crankshaft and camshaft
timing marks always rotate engine from crankshaft.
Camshaft should not be rotated after timing belt is
removed. Damage to valve components may occur.
Always align timing marks before removing timing
belt.
(9) Before the removal of the timing belt, rotate
crankshaft until the TDC mark on oil pump housing
aligns with the TDC mark on crankshaft sprocket
(trailing edge of sprocket tooth) (Fig. 95).
NOTE: The crankshaft sprocket TDC mark is
located on the trailing edge of the sprocket tooth.
Failure to align trailing edge of sprocket tooth to
TDC mark on oil pump housing will cause the cam-
shaft timing marks to be misaligned.
(10) Install 6 mm Allen wrench into belt tensioner.
Before rotating the tensioner, insert the long end of a
1/8º or 3 mm Allen wrench into the pin hole on the
front of the tensioner (Fig. 96). While rotating the
tensioner counterclockwise, push in lightly on the
1/8º or 3 mm Allen wrench, until it slides into the
locking hole.
(11) Remove timing belt.
REMOVAL - CRANKSHAFT SPROCKET
(1) Disconnect negative battery cable.
(2) Remove timing belt (Refer to 9 - ENGINE/
VALVE TIMING/TIMING BELT/CHAIN AND
SPROCKETS - REMOVAL).
(3) Remove crankshaft sprocket using Special
Tools 6793 and insert C-4685-C2 (Fig. 97).
CLEANING
Do Not attempt to clean a timing belt. If contami-
nation from oil, grease, or coolants have occurred, the
timing belt should be replaced.
Clean all sprockets using a suitable solvent. Clean
all sprocket grooves of any debris.
Fig. 95 Crankshaft and Camshaft Timing
1 - CAMSHAFT TIMING MARKS
2 - CRANKSHAFT TDC MARKS
3 - TRAILING EDGE OF SPROCKET TOOTH
KJENGINE9s-55

(8) Check if the spring tang is within the tolerance
window (Fig. 103). If the spring tang is within the
tolerance window, the installation process is complete
and nothing further is required. If the spring tang is
not within the tolerance window, repeat Steps 5
through 7.
(9) Install timing belt front covers and bolts.
(Refer to 9 - ENGINE/VALVE TIMING/TIMING
BELT / CHAIN COVER(S) - INSTALLATION)
(10) Install air conditioning/generator belt ten-
sioner and pulley. (Refer to 7 - COOLING/ACCES-
SORY DRIVE/BELT TENSIONERS -
INSTALLATION)
(11) Install crankshaft vibration damper. (Refer to
9 - ENGINE/ENGINE BLOCK/VIBRATION
DAMPER - INSTALLATION)
(12) Install accessory drive belts. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION)
(13) Install drive belt splash shield.
(14) Install air cleaner housing, upper cover, and
clean air tube.
Fig. 101 Timing Belt Tension Adjustment
1 - ALIGN SETTING NOTCH WITH SPRING TANG
2 - TOP PLATE
3 - 6mm ALLEN WRENCH
4 - LOCK NUT
5 - SETTING NOTCH
6 - SPRING TANG
Fig. 102 Crankshaft and Camshaft Timing
1 - CAMSHAFT TIMING MARKS
2 - CRANKSHAFT TDC MARKS
3 - TRAILING EDGE OF SPROCKET TOOTH
Fig. 103 Timing Belt Tension Verification
1 - SPRING TANG
2 - TOLERANCE WINDOW
9s - 58 ENGINEKJ
TIMING BELT AND SPROCKET(S) (Continued)

OPERATION
Fuel is picked up in the fuel tank by the fuel pump
module. This module is located on the bottom of the
fuel tank.
A fuel return system is provided within the fuel
pump module using check valves. A separate fuel
return line from the engine to the tank is not used.
The fuel pressure regulator and the main fuel filter
are not combined. They are separate items.
The fuel tank assembly consists of: the fuel tank,
fuel pump module assembly, fuel pump module lock
ring/gasket, ORVR components. Refer to 25, Emis-
sion Control System for ORVR information.
A fuel filler/vent tube assembly using a pressure/
vacuum, 1/4 turn fuel filler cap is used. The fuel
filler tube contains a flap door located below the fuel
fill cap. A one-way check valve is installed into the
tanks fuel fill fitting.
Also to be considered part of the fuel system is the
evaporation control system and ORVR system. This
is designed to reduce the emission of fuel vapors into
the atmosphere. The description and function of the
Evaporative Control System is found in 25, Emission
Control Systems.
Both fuel filters (mounted to front of fuel tank, and
inside the bottom fuel pump module) are designed for
extended service. They do not require normal sched-
uled maintenance. The bottom section of the fuel
pump module (with included filter) should only be
replaced if a diagnostic procedure indicates to do so.
Also, the fuel filter mounted to the front of the fuel
tank should only be replaced if a diagnostic proce-
dure indicates to do so.
DIAGNOSIS AND TESTING - FUEL PRESSURE
LEAK DOWN TEST
Use this test in conjunction with the Fuel Pump
Pressure Test and Fuel Pump Capacity Test.
Check Valve Operation:The electric fuel pump
outlet contains a one-way check valve to prevent fuel
flow back into the tank and to maintain fuel supply
line pressure (engine warm) when pump is not oper-
ational. It is also used to keep the fuel supply line
full of gasoline when pump is not operational. After
the vehicle has cooled down, fuel pressure may drop
to 0 psi (cold fluid contracts), but liquid gasoline will
remain in fuel supply line between the check valve
and fuel injectors.Fuel pressure that has
dropped to 0 psi on a cooled down vehicle
(engine off) is a normal condition.When the elec-
tric fuel pump is activated, fuel pressure should
immediately(1±2 seconds) rise to specification.
Abnormally long periods of cranking to restart a
hotengine that has been shut down for a short
period of time may be caused by:
²Fuel pressure bleeding past a fuel injector(s).²Fuel pressure bleeding past the check valve in
the fuel pump module.
(1) Disconnect the fuel inlet line at fuel rail. Refer
to Quick Connect Fittings for procedures. On some
engines, air cleaner housing removal may be neces-
sary before fuel line disconnection.
(2) Obtain correct Fuel Line Pressure Test Adapter
Tool Hose. Tool number 6539 is used for 5/16º fuel
lines and tool number 6631 is used for 3/8º fuel lines.
(3) Connect correct Fuel Line Pressure Test
Adapter Tool Hose between disconnected fuel line
and fuel rail (Fig. 2).
(4) Connect the 0-414 kPa (0-60 psi) fuel pressure
test gauge (from Gauge Set 5069) to the test port on
the appropriate Adaptor Tool.The DRBtIII Scan
Tool along with the PEP module, the 500 psi
pressure transducer, and the transducer-to-test
port adapter may also be used in place of the
fuel pressure gauge.
The fittings on both tools must be in good
condition and free from any small leaks before
performing the proceeding test.
(5) Start engine and bring to normal operating
temperature.
(6) Observe test gauge. Normal operating pressure
should be 339 kPa +/±34 kPa (49.2 psi +/±5 psi).
(7) Shut engine off.
Fig. 2 CONNECTING ADAPTER TOOLÐTYPICAL
1 - VEHICLE FUEL LINE
2 - TEST PORT ªTº
3 - SPECIAL TOOL 6923, 6631, 6541 OR 6539
4 - FUEL PRESSURE TEST GAUGE
5 - FUEL LINE CONNECTION AT RAIL
6 - FUEL RAIL
KJFUEL DELIVERY 14 - 3
FUEL DELIVERY (Continued)

FUEL PUMP
DESCRIPTION
The electric fuel pump is located inside of the fuel
pump module. A 12 volt, permanent magnet, electric
motor powers the fuel pump. The electric fuel pump
is not a separate, serviceable component.
OPERATION
Voltage to operate the electric pump is supplied
through the fuel pump relay.
Fuel is drawn in through a filter at the bottom of
the module and pushed through the electric motor
gearset to the pump outlet.
Check Valve Operation:The bottom section of
the fuel pump module contains a one-way check
valve to prevent fuel flow back into the tank and to
maintain fuel supply line pressure (engine warm)
when pump is not operational. It is also used to keep
the fuel supply line full of gasoline when pump is not
operational. After the vehicle has cooled down, fuel
pressure may drop to 0 psi (cold fluid contracts), but
liquid gasoline will remain in fuel supply line
between the check valve and fuel injectors.Fuel
pressure that has dropped to 0 psi on a cooled
down vehicle (engine off) is a normal condition.
Refer to the Fuel Pressure Leak Down Test for more
information.
The electric fuel pump is not a separate, service-
able component.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - FUEL PUMP
CAPACITY TEST
Before performing this test, verify fuel pump
pressure. Refer to Fuel Pump Pressure Test.
Use this test in conjunction with the Fuel Pres-
sure Leak Down Test.
(1) Release fuel system pressure. Refer to Fuel
Pressure Release Procedure.
(2) Disconnect fuel supply line at fuel rail. Refer to
Quick-Connect Fittings. Some engines may require
air cleaner housing removal before line disconnection.
(3) Obtain correct Fuel Line Pressure Test Adapter
Tool Hose. Tool number 6539 is used for 5/16º fuel
lines and tool number 6631 is used for 3/8º fuel lines.
(4) Connect correct Fuel Line Pressure Test
Adapter Tool Hose into disconnected fuel supply line.
Insert other end of Adaptor Tool Hose into a gradu-
ated container.
(5) Remove fuel fill cap.(6) To activate fuel pump and pressurize system,
obtain DRBtscan tool and actuate ASD Fuel System
Test.
(7) A good fuel pump will deliver at least 1/10 liter
of fuel in 7 seconds. Do not operate fuel pump for
longer than 7 seconds with fuel line disconnected as
fuel pump module reservoir may run empty.
(a) If capacity is lower than specification, but
fuel pump can be heard operating through fuel fill
cap opening, check for a kinked/damaged fuel sup-
ply line somewhere between fuel rail and fuel
pump module.
(b) If line is not kinked/damaged, and fuel pres-
sure is OK, but capacity is low, replace fuel filter.
Refer to Fuel Filter Removal/Installation for addi-
tional information.
(c) If both fuel pressure and capacity are low,
replace bottom section of fuel pump module. Refer
to Fuel Pump Module Removal/Installation.
DIAGNOSIS AND TESTING - FUEL PUMP
PRESSURE TEST
Use this test in conjunction with the Fuel Pump
Capacity Test, Fuel Pressure Leak Down Test and
Fuel Pump Amperage Test found elsewhere in this
group.
Check Valve Operation:The bottom section of
the fuel pump module contains a one-way check
valve to prevent fuel flow back into the tank and to
maintain fuel supply line pressure (engine warm)
when pump is not operational. It is also used to keep
the fuel supply line full of gasoline when pump is not
operational. After the vehicle has cooled down, fuel
pressure may drop to 0 psi (cold fluid contracts), but
liquid gasoline will remain in fuel supply line
between the check valve and fuel injectors.Fuel
pressure that has dropped to 0 psi on a cooled
down vehicle (engine off) is a normal condition.
When the electric fuel pump is activated, fuel pres-
sure shouldimmediately(1±2 seconds) rise to spec-
ification.
The fuel system is equipped with a separate fuel
pump module mounted, fuel pressure regulator. The
fuel filter is remotely mounted. The fuel pressure
regulator is not controlled by engine vacuum.
WARNING: THE FUEL SYSTEM IS UNDER CON-
STANT FUEL PRESSURE EVEN WITH THE ENGINE
OFF. BEFORE DISCONNECTING FUEL LINE AT
FUEL RAIL, THIS PRESSURE MUST BE RELEASED.
REFER TO THE FUEL SYSTEM PRESSURE
RELEASE PROCEDURE.
KJFUEL DELIVERY 14 - 15

REMOVAL
(1) Remove fuel rail. Refer to Fuel Injector Rail
Removal.
(2) Disconnect clip(s) that retain fuel injector(s) to
fuel rail (Fig. 10).
INSTALLATION
(1) Install fuel injector(s) into fuel rail assembly
and install retaining clip(s).
(2) If same injector(s) is being reinstalled, install
new o-ring(s).
(3) Apply a small amount of clean engine oil to
each injector o-ring. This will aid in installation.
(4) Install fuel rail. Refer to Fuel Rail Installation.
(5) Start engine and check for fuel leaks.
FUEL PUMP RELAY
DESCRIPTION
The 5±pin, 12±volt, fuel pump relay is located in
the Power Distribution Center (PDC). Refer to the
label on the PDC cover for relay location.
OPERATION
The Powertrain Control Module (PCM) energizes
the electric fuel pump through the fuel pump relay.
The fuel pump relay is energized by first applying
battery voltage to it when the ignition key is turnedON, and then applying a ground signal to the relay
from the PCM.
Whenever the ignition key is turned ON, the elec-
tric fuel pump will operate. But, the PCM will shut-
down the ground circuit to the fuel pump relay in
approximately 1±3 seconds unless the engine is oper-
ating or the starter motor is engaged.
DIAGNOSIS AND TESTING - FUEL PUMP
RELAY
For procedures, refer to ASD Relay Diagnosis and
Testing in the Ignition section.
REMOVAL
The fuel pump relay is located in the Power Distri-
bution Center (PDC) (Fig. 11). Refer to label on PDC
cover for relay location.
(1) Remove PDC cover.
(2) Remove relay from PDC.
(3) Check condition of relay terminals and PDC
connector terminals for damage or corrosion. Repair
if necessary before installing relay.
(4) Check for pin height (pin height should be the
same for all terminals within the PDC connector).
Repair if necessary before installing relay.
INSTALLATION
The fuel pump relay is located in the Power Distri-
bution Center (PDC). Refer to label on PDC cover for
relay location.
(1) Install relay to PDC.
(2) Install cover to PDC.
Fig. 10 INJECTOR RETAINING CLIP
1 - PLIERS
2 - INJECTOR CLIP
3 - FUEL INJECTOR
4 - FUEL RAIL - TYPICAL
Fig. 11 POWER DISTRIBUTION CENTER (PDC)
1 - BATTERY
2 - PDC
3 - PDC COVER
14 - 34 FUEL INJECTIONKJ
FUEL INJECTOR (Continued)

IDLE AIR CONTROL MOTOR
DESCRIPTION
The IAC stepper motor is mounted to the throttle
body, and regulates the amount of air bypassing the
control of the throttle plate. As engine loads and
ambient temperatures change, engine rpm changes.
A pintle on the IAC stepper motor protrudes into a
passage in the throttle body, controlling air flow
through the passage. The IAC is controlled by the
Powertrain Control Module (PCM) to maintain the
target engine idle speed.
OPERATION
At idle, engine speed can be increased by retract-
ing the IAC motor pintle and allowing more air to
pass through the port, or it can be decreased by
restricting the passage with the pintle and diminish-
ing the amount of air bypassing the throttle plate.
The IAC is called a stepper motor because it is
moved (rotated) in steps, or increments. Opening the
IAC opens an air passage around the throttle blade
which increases RPM.
The PCM uses the IAC motor to control idle speed
(along with timing) and to reach a desired MAP dur-
ing decel (keep engine from stalling).
The IAC motor has 4 wires with 4 circuits. Two of
the wires are for 12 volts and ground to supply elec-
trical current to the motor windings to operate the
stepper motor in one direction. The other 2 wires are
also for 12 volts and ground to supply electrical cur-
rent to operate the stepper motor in the opposite
direction.
To make the IAC go in the opposite direction, the
PCM just reverses polarity on both windings. If only
1 wire is open, the IAC can only be moved 1 step
(increment) in either direction. To keep the IAC
motor in position when no movement is needed, the
PCM will energize both windings at the same time.
This locks the IAC motor in place.
In the IAC motor system, the PCM will count
every step that the motor is moved. This allows the
PCM to determine the motor pintle position. If the
memory is cleared, the PCM no longer knows the
position of the pintle. So at the first key ON, the
PCM drives the IAC motor closed, regardless of
where it was before. This zeros the counter. Fromthis point the PCM will back out the IAC motor and
keep track of its position again.
When engine rpm is above idle speed, the IAC is
used for the following:
²Off-idle dashpot (throttle blade will close quickly
but idle speed will not stop quickly)
²Deceleration air flow control
²A/C compressor load control (also opens the pas-
sage slightly before the compressor is engaged so
that the engine rpm does not dip down when the
compressor engages)
²Power steering load control
The PCM can control polarity of the circuit to con-
trol direction of the stepper motor.
IAC Stepper Motor Program:The PCM is also
equipped with a memory program that records the
number of steps the IAC stepper motor most recently
advanced to during a certain set of parameters. For
example: The PCM was attempting to maintain a
1000 rpm target during a cold start-up cycle. The last
recorded number of steps for that may have been
125. That value would be recorded in the memory
cell so that the next time the PCM recognizes the
identical conditions, the PCM recalls that 125 steps
were required to maintain the target. This program
allows for greater customer satisfaction due to
greater control of engine idle.
Another function of the memory program, which
occurs when the power steering switch (if equipped),
or the A/C request circuit, requires that the IAC step-
per motor control engine rpm, is the recording of the
last targeted steps into the memory cell. The PCM
can anticipate A/C compressor loads. This is accom-
plished by delaying compressor operation for approx-
imately 0.5 seconds until the PCM moves the IAC
stepper motor to the recorded steps that were loaded
into the memory cell. Using this program helps elim-
inate idle-quality changes as loads change. Finally,
the PCM incorporates a9No-Load9engine speed lim-
iter of approximately 1800 - 2000 rpm, when it rec-
ognizes that the TPS is indicating an idle signal and
IAC motor cannot maintain engine idle.
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 IAC motor through the PCM.
KJFUEL INJECTION 14 - 35