2002 JEEP GRAND CHEROKEE Cylinder head removal

(9) Disconnect speed control cable at throttle body
(if equipped). Refer to Speed Control Cable.
(10) Disconnect automatic transmission cable at
throttle body (if equipped).
(11) Remove cable routing bracket at intake mani-
fold.
(12) Clean dirt/debris from each fuel injector at
intake manifold.
(13) Remove fuel rail mounting nuts/bolts (Fig.
24).
(14) Remove fuel rail by gently rocking until all
fuel injectors have cleared machined holes at intake
manifold.
(15) If fuel injectors are to be removed, refer to
Fuel Injector Removal/Installation.
INSTALLATION
INSTALLATION - 4.7L
(1) If fuel injectors are to be installed, refer to Fuel
Injector Removal/Installation.
(2) Apply a small amount of engine oil to each fuel
injector o-ring. This will help in fuel rail installation.
(3) Position fuel rail/fuel injector assembly to
machined injector openings in cylinder head.
(4) Guide each injector into cylinder head. Be care-
ful not to tear injector o-rings.(5) Pushrightside of fuel rail down until fuel
injectors have bottomed on cylinder head shoulder.
Pushleftfuel rail down until injectors have bot-
tomed on cylinder head shoulder.
(6) Install 4 fuel rail mounting bolts and tighten to
27 N´m (20 ft. lbs.).
(7) Install ignition coils. Refer to Ignition Coil
Removal/Installation.
(8) Connect electrical connectors to throttle body.
(9) Connect electrical connectors to MAP and IAT
sensors.
(10) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 23). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(11) Connect vacuum lines to throttle body.
(12) Connect fuel line latch clip and fuel line to
fuel rail. Refer to Quick-Connect Fittings.
(13) Connect wiring to rear of generator.
(14) Install air box to throttle body.
(15) Install air duct to air box.
(16) Connect battery cable to battery.
(17) Start engine and check for leaks.
INSTALLATION - 4.0L
(1) If fuel injectors are to be installed, refer to Fuel
Injector Removal/Installation.
(2) Clean each injector bore at intake manifold.
(3) Apply a small amount of clean engine oil to
each injector o-ring. This will aid in installation.
(4) Position tips of all fuel injectors into the corre-
sponding injector bore in intake manifold. Seat injec-
tors into manifold.
(5) Install and tighten fuel rail mounting bolts to
11  3 N´m (100  25 in. lbs.) torque.
(6) Connect electrical connectors at all fuel injec-
tors. To install connector, refer to (Fig. 25). Push con-
nector onto injector (1) and then push and lock red
colored slider (2). Verify connector is locked to injec-
tor by lightly tugging on connector.
(7) Connect fuel line and fuel line latch clip to fuel
rail. Refer Quick-Connect Fittings.
(8) Install protective cap to pressure test port fit-
ting (if equipped).
(9) Install cable routing bracket to intake mani-
fold.
(10) Connect throttle cable at throttle body.
(11) Connect speed control cable at throttle body (if
equipped).
(12) Connect automatic transmission cable at
throttle body (if equipped).
(13) Install oxygen sensor wiring clip nuts to fuel
rail mounting studs (certain emissions packages
only).
Fig. 25 Remove/Install Injector ConnectorÐ4.0L
Engine
14 - 18 FUEL DELIVERYWJ
FUEL RAIL (Continued)

(5) Push sensor against flywheel/drive plate. With
sensor pushed against flywheel/drive plate, tighten
mounting bolt to 7 N´m (60 in. lbs.) torque.
(6) Route sensor wiring harness into wire shield.
(7) Connect sensor pigtail harness electrical con-
nector to main wiring harness.
INSTALLATION - 4.7L
(1) Clean out machined hole in engine block.
(2) Apply a small amount of engine oil to sensor
o-ring.
(3) Install sensor into engine block with a slight
rocking action. Do not twist sensor into position as
damage to o-ring may result.
CAUTION: Before tightening sensor mounting bolt,
be sure sensor is completely flush to cylinder
block. If sensor is not flush, damage to sensor
mounting tang may result.
(4) Install mounting bolt and tighten to 28 N´m
(21 ft. lbs.) torque.
(5) Connect electrical connector to sensor.
(6) Install starter motor. Refer to Starter Removal/
Installation.
FUEL INJECTOR
DESCRIPTION
A separate fuel injector (Fig. 24) is used for each
individual cylinder.
OPERATION
OPERATION
The fuel injectors are electrical solenoids. The
injector contains a pintle that closes off an orifice at
the nozzle end. When electric current is supplied to
the injector, the armature and needle move a short
distance against a spring, allowing fuel to flow out
the orifice. Because the fuel is under high pressure, a
fine spray is developed in the shape of a pencil
stream. The spraying action atomizes the fuel, add-
ing it to the air entering the combustion chamber.
The top (fuel entry) end of the injector (Fig. 24) is
attached into an opening on the fuel rail.
The nozzle (outlet) ends of the injectors are posi-
tioned into openings in the intake manifold just
above the intake valve ports of the cylinder head.
The engine wiring harness connector for each fuel
injector is equipped with an attached numerical tag
(INJ 1, INJ 2 etc.). This is used to identify each fuel
injector.
The injectors are electrically energized, individu-
ally and in a sequential order by the Powertrain Con-
trol Module (PCM). The PCM will adjust injector
pulse width by switching the ground path to each
individual injector on and off. Injector pulse width is
the period of time that the injector is energized. The
PCM will adjust injector pulse width based on vari-
ous inputs it receives.
Battery voltage is supplied to the injectors through
the ASD relay.
The PCM determines injector pulse width based on
various inputs.
OPERATION - PCM OUTPUT
The nozzle ends of the injectors are positioned into
openings in the intake manifold just above the intake
valve ports of the cylinder head. The engine wiring
harness connector for each fuel injector is equipped
with an attached numerical tag (INJ 1, INJ 2 etc.).
This is used to identify each fuel injector with its
respective cylinder number.
The injectors are energized individually in a
sequential order by the Powertrain Control Module
(PCM). The PCM will adjust injector pulse width by
switching the ground path to each individual injector
on and off. Injector pulse width is the period of time
that the injector is energized. The PCM will adjust
injector pulse width based on various inputs it
receives.
Battery voltage (12 volts +) is supplied to the injec-
tors through the ASD relay. The ASD relay will shut-
down the 12 volt power source to the fuel injectors if
the PCM senses the ignition is on, but the engine is
not running. This occurs after the engine has not
been running for approximately 1.8 seconds.
Fig. 24 Fuel InjectorÐ4.0L/4.7L Engines
1 - FUEL INJECTOR
2 - NOZZLE
3 - TOP (FUEL ENTRY)
WJFUEL INJECTION 14 - 43
CRANKSHAFT POSITION SENSOR (Continued)

(11) While the vehicle is in park, use the DRB III
to activate the hydraulic fan to full fan operation and
briefly rev the engine up to 3000 rpm to fully engage
the hydraulic fan.
(12) Check the fluid level add if necessary.
REMOVAL
REMOVAL - 4.0L ENGINE
(1) Remove serpentine drive belt,(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove pressure and return hoses from pump
and drain the pump.
(3)
Loosen the pump bracket bolt at the engine block.
(4) Remove 3 pump mounting bolts (Fig. 4)
through pulley access holes.
(5) Tilt pump downward and remove from engine.
(6) Remove pulley from pump.
REMOVAL - 4.7L ENGINE
(1) Remove the serpentine drive belt,(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove the pressure and return hoses from
pump and drain pump.
(3) Remove 3 pump mounting bolts through pulley
access holes (Fig. 5).
(4) Remove the pump from the vehicle.
INSTALLATION
INSTALLATION - 4.0L ENGINE
(1) Install pulley on pump.
(2) Install pump on the engine mounting bracket.
(3) Install 3 pump mounting bolts and tighten to
27 N´m (20 ft. lbs.).
(4) Tighten pump bracket bolt to 57 N´m (42 ft.
lbs.).
(5) Install the pressure line on the pump and
tighten to 28 N´m (21 ft. lbs.).
(6) Install the return hoses on pump.
(7) Install the drive belt,(Refer to 7 - COOLING/
ACCESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
(8) Add power steering fluid,(Refer to 19 - STEER-
ING/PUMP - STANDARD PROCEDURE).
INSTALLATION - 4.7L ENGINE
(1) Position the pump on the left cylinder head
and install bolts through pulley access holes. Tighten
bolts to 28 N´m (21 ft. lbs.).
(2) Install the pressure and return hoses to pump.
(3) Install serpentine drive belt,(Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION).
(4) Add power steering fluid,(Refer to 19 - STEER-
ING/PUMP - STANDARD PROCEDURE).
Fig. 4 PUMP MOUNTING ± 4.0L
1 - PUMP ASSEMBLY
2 - PUMP BRACKET
Fig. 5 Pump Mounting
1 - LEFT CYLINDER HEAD
2 - PUMP
19 - 34 PUMPWJ
PUMP (Continued)

The high pressure relief valve vents only enough
refrigerant to reduce the system pressure, and then
re-seats itself. The majority of the refrigerant is con-
served in the system. If the valve vents refrigerant, it
does not mean that the valve is faulty.
The high pressure relief valve is a factory-cali-
brated unit. The valve cannot be adjusted or
repaired, and must not be removed or otherwise dis-
turbed. The valve is only serviced as a part of the
compressor assembly.
DIAGNOSIS AND TESTING - COMPRESSOR
NOISE
When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neu-
tral, engine speed, engine temperature, and any
other special conditions. Noises that develop during
air conditioning operation can often be misleading.
For example: What sounds like a failed front bearing
or connecting rod, may be caused by loose bolts, nuts,
mounting brackets, or a loose compressor clutch
assembly.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for a compressor
noise. Improper belt tension can cause a misleading
noise when the compressor clutch is engaged, which
may not occur when the compressor clutch is disen-
gaged. Check the serpentine drive belt condition and
tension as described in Cooling before beginning this
procedure.
(1) Select a quiet area for testing. Duplicate the
complaint conditions as much as possible. Switch the
compressor on and off several times to clearly iden-
tify the compressor noise. Listen to the compressor
while the clutch is engaged and disengaged. Probe
the compressor with an engine stethoscope or a long
screwdriver with the handle held to your ear to bet-
ter localize the source of the noise.
(2) Loosen all of the compressor mounting hard-
ware and retighten. Tighten the compressor clutch
mounting nut. Be certain that the clutch coil is
mounted securely to the compressor, and that the
clutch plate and pulley are properly aligned and have
the correct air gap. (Refer to 24 - HEATING & AIR
CONDITIONING/CONTROLS/A/C COMPRESSOR
CLUTCH - INSTALLATION)
(3) To duplicate a high-ambient temperature condi-
tion (high head pressure), restrict the air flow
through the condenser. Install a manifold gauge set
to be certain that the discharge pressure does not
exceed 2760 kPa (400 psi).
(4) Check the refrigerant system plumbing for
incorrect routing, rubbing or interference, which cancause unusual noises. Also check the refrigerant lines
for kinks or sharp bends that will restrict refrigerant
flow, which can cause noises. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - CAU-
TION - REFRIGERANT HOSES/LINES/TUBES
PRECAUTIONS)
(5) If the noise is from opening and closing of the
high pressure relief valve, reclaim, evacuate, and
recharge the refrigerant system. (Refer to 24 - HEAT-
ING & AIR CONDITIONING/PLUMBING - STAN-
DARD PROCEDURE - REFRIGERANT RECOVERY)
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - STANDARD PROCEDURE - REFRIG-
ERANT SYSTEM EVACUATE) (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)If the high pressure relief valve still
does not seat properly, replace the a/c compressor.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING/A/C COMPRESSOR - REMOVAL)
(6) If the noise is from liquid slugging on the suc-
tion line, check the refrigerant oil level and the
refrigerant system charge. (Refer to 24 - HEATING
& AIR CONDITIONING/PLUMBING/REFRIGER-
ANT OIL - STANDARD PROCEDURE) (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
SPECIFICATIONS - CHARGE CAPACITY).
(7) If the noise continues, replace the compressor
and repeat Step 1.
REMOVAL
REMOVAL
The compressor may be removed and repositioned
without disconnecting the refrigerant lines or dis-
charging the refrigerant system. Discharging is not
necessary if servicing the compressor clutch or clutch
coil, the engine, the cylinder head, or the generator.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
(1) Recover the refrigerant from the system. (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMB-
ING - STANDARD PROCEDURE - REFRIGERANT
RECOVERY)
(2) Disconnect and isolate the battery negative
cable.
(3) Remove the serpentine drive belt. Refer to
Cooling for the procedures.
(4) Unplug the compressor clutch coil wire harness
connector.
24 - 58 PLUMBINGWJ
A/C COMPRESSOR (Continued)

REMOVAL - 2.7L TURBO DIESEL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
(1) Disconnect the negative battery cable.
(2) Recover the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT
RECOVERY)
(3) Remove the refrigerant line retaining fastener
from the H-Valve Block (Fig. 10). Remove the line
and gasket from the H-Valve block and cap or tape
over both ends.
(4) Remove the refrigerant line support bracket
bolt from the cylinder head cap.
(5) Remove the refrigerant line retaining fastener
from the compressor inlet fitting. Remove the line
and cap the compressor outlet tube to prevent con-
tamination of the system.
(6) Unclip and remove the suction line from the
vehicle.
INSTALLATION
INSTALLATION
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Remove the tape or plugs from the suction line
block fitting and the manifold on the compressor.
Install the suction line block fitting to the manifold
on the compressor. Tighten the mounting bolt to 25.4
N´m (225 in. lbs.).
(2) Remove the tape or plugs from the refrigerant
line fittings on the evaporator outlet and the suction
line. Slide the suction line copnnection block over the
liquid line and evaporator stud. Tighten the retaining
nut to 28 N´m (250 in. lbs.).
(3) Connect the battery negative cable.
(4) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(5) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
Fig. 10 Suction-Discharge Lines- RHD (LHD-typical)
1 - SUCTION LINE
2 - H-BLOCK
3 - RECEIVER DRIER
4 - DISCHARGE LINE & SERVICE PORT
5 - A/C COMPRESSOR
6 - DISCHARGE LINE & CONDENSOR CONNECTION
24 - 68 PLUMBINGWJ
SUCTION LINE (Continued)

INSTALLATION - 2.7L TURBO DIESEL
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
Any kinks or sharp bends in the refrigerant plumb-
ing will reduce the capacity of the entire air condi-
tioning system. Kinks and sharp bends reduce the
flow of refrigerant in the system. A good rule for the
flexible hose refrigerant lines is to keep the radius of
all bends at least ten times the diameter of the hose.
In addition, the flexible hose refrigerant lines should
be routed so they are at least 80 millimeters (3
inches) from the exhaust manifold.
High pressures are produced in the refrigerant sys-
tem when the air conditioning compressor is operat-
ing. Extreme care must be exercised to make sure
that each of the refrigerant system connections is
pressure-tight and leak free. It is a good practice to
inspect all flexible hose refrigerant lines at least once
a year to make sure they are in good condition and
properly routed.
(1) Carefully position the suction line in the vehi-
cle.
(2) Remove the cap or tape and install the suction
line on the compressor. Be certain the sealing o-ring
is well lubricated with PAG oil and free of tears.
Torque the retaining fastener to 22 N´m (200 in. lbs.).
(3) Position and install the refrigerant line support
bracket bolt on the cylinder head cap. Torque the bolt
to 20 N´m (177 in. lbs.).
(4) Remove the cap or tape and install the suction
line on the H-Valve Block. Be certain the sealing
O-ring is well lubricated with PAG oil and free of
tears. Torque the retaining fastener to 28 N´m (21 ft.
lbs.).
(5) Install the tie-straps retaining the wire har-
ness on the suction line.
(6) Evacuate the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM EVACUATE)
(7) Charge the refrigerant system. (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING -
STANDARD PROCEDURE - REFRIGERANT SYS-
TEM CHARGE)
(8) Connect the negative battery cable.
A/C EVAPORATOR
DESCRIPTION
The evaporator coil is located in the HVAC hous-
ing, under the instrument panel. The evaporator coil
is positioned in the HVAC housing so that all air that
enters the housing must pass over the fins of the
evaporator before it is distributed through the sys-
tem ducts and outlets. However, air passing over the
evaporator coil fins will only be conditioned when the
compressor is engaged and circulating refrigerant
through the evaporator coil tubes.
OPERATION
Refrigerant enters the evaporator from the orifice
tube as a low-temperature, low-pressure liquid. As
air flows over the fins of the evaporator, the humidity
in the air condenses on the fins, and the heat from
the air is absorbed by the refrigerant. Heat absorp-
tion causes the refrigerant to boil and vaporize. The
refrigerant becomes a low-pressure gas before it
leaves the evaporator.
The evaporator coil cannot be repaired and, if
faulty or damaged, it must be replaced.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN AN ACCIDENTAL
AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
WARNING: REVIEW THE WARNINGS AND CAU-
TIONS IN THE FRONT OF THIS SECTION BEFORE
PERFORMING THE FOLLOWING OPERATION.
(Refer to 24 - HEATING & AIR CONDITIONING/
PLUMBING - WARNING) (Refer to 24 - HEATING &
AIR CONDITIONING/PLUMBING - CAUTION)
(1) Remove and disassemble the HVAC housing.
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - REMOVAL)
(Refer to 24 - HEATING & AIR CONDITIONING/
DISTRIBUTION/HVAC HOUSING - DISASSEMBLY)
(2) Lift the evaporator coil unit out of the lower
half of the HVAC housing (Fig. 11).
WJPLUMBING 24 - 69
SUCTION LINE (Continued)