2004 INFINITI QX56 engine

AUTOMATIC SPEED CONTROL DEVICE (ASCD)
EC-647
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionUBS00HE7
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
BASIC ASCD SYSTEM
Refer to Owner's Manual for ASCD operating instructions.
Automatic Speed Control Device (ASCD) allows a driver to keep vehicle at predetermined constant speed
without pressing accelerator pedal. Driver can set vehicle speed in advance between approximately 40 km/h
(25 MPH) and 144 km/h (89 MPH).
ECM controls throttle angle of electric throttle control actuator to regulate engine speed.
Operation status of ASCD is indicated by CRUISE indicator and SET indicator in combination meter. If any
malfunction occurs in ASCD system, it automatically deactivates control.
SET OPERATION
Press ON/OFF(MAIN) switch. (The CRUISE indicator in combination meter illuminates.)
When vehicle speed reaches a desired speed between approximately 40 km/h (25 MPH) and 144 km/h (89
MPH), press COAST/SET switch. (Then SET indicator in combination meter illuminates.)
ACCEL OPERATION
If the ACCEL/RESUME switch is pressed during cruise control driving, increase the vehicle speed until the
switch is released or vehicle speed reaches maximum speed controlled by the system.
And then ASCD will keep the new set speed.
CANCEL OPERATION
When any of following conditions exist, cruise operation will be canceled.

CANCEL switch is pressed

More than 2 switches at ASCD steering switch are pressed at the same time (Set speed will be cleared)

Brake pedal is depressed

Selector lever is changed to N, P, R position

Vehicle speed decreased to 13 km/h (8 MPH) lower than the set speed

VDC/TCS system is operated
When the ECM detects any of the following conditions, the ECM will cancel the cruise operation and inform
the driver by blinking indicator lamp.

Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE lamp may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE lamp will
stop blinking and the cruise operation will be able to work by pressing COAST/SET switch or ACCEL/
RESUME switch.

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If ON/OFF(MAIN) switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled
and vehicle speed memory will be erased.
COAST OPERATION
When the COAST/SET switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will keep the new set speed.
Sensor Input signal to ECM ECM function Actuator
ASCD brake switch Brake pedal operation
ASCD vehicle speed controlElectric throttle control
actuator Stop lamp switch Brake pedal operation
ASCD steering switch ASCD steering switch operation
Park/Neutral position (PNP)
switchGear position
Combination meter* Vehicle speed
TCM* Powertrain revolution

SERVICE DATA AND SPECIFICATIONS (SDS)
EC-649
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SERVICE DATA AND SPECIFICATIONS (SDS)PFP:00030
Fuel PressureUBS00HE9
Idle Speed and Ignition TimingUBS00HEA
*1: Under the following conditions:

Air conditioner switch: OFF

Electric load: OFF (Lights and heater fan)

Steering wheel: Kept in straight-ahead position
Calculated Load ValueUBS00HEB
Mass Air Flow SensorUBS00HEC
*: Engine is warmed up to normal operating temperature and running under no-load.
Intake Air Temperature SensorUBS00HED
Engine Coolant Temperature SensorUBS00HEE
A/F Sensor 1 HeaterUBS00HEF
Heated Oxygen sensor 2 HeaterUBS00HEG
Crankshaft Position Sensor (POS)UBS00HEH
Refer to EC-260, "Component Inspection" .
Camshaft Position Sensor (PHASE)UBS00HEI
Refer to EC-266, "Component Inspection" .
Throttle Control MotorUBS00HEJ
Fuel pressure at idling kPa (kg/cm2 , psi)Approximately 350 (3.57, 51)
Target idle speed
No-load*1 (in P or N position)650±50 rpm
Air conditioner: ON In P or N position 700 rpm or more
Ignition timing In P or N position 15° ± 5° BTDC
Condition Calculated load value % (Using CONSULT-II or GST)
At idle14.0 - 33.0
At 2,500 rpm12.0 - 25.0
Supply voltage Battery voltage (11 - 14V)
Output voltage at idle1.1 - 1.4V*
Mass air flow (Using CONSULT-II or GST)3.0 - 9.0 g·m/sec at idle*
9.0 - 28.0 g·m/sec at 2,500 rpm*
Temperature °C (°F) Resistance kΩ
25 (77)1.9 - 2.1
80 (176)0.31 - 0.37
Temperature °C (°F) Resistance kΩ
20 (68)2.1 - 2.9
50 (122)0.68 - 1.00
90 (194)0.236 - 0.260
Resistance [at 25°C (77°F)] 3.3 - 4.3Ω
Resistance [at 25°C (77°F)] 5.0 - 7.0Ω
Resistance [at 25°C (77°F)] Approximately 1 - 15Ω

EI-4
PREPARATION
Revision: August 20072004 QX56
PREPARATIONPFP:00002
Special Service ToolsEIS002X3
The actual shapes of Kent-Moore tools may differ from those of special service tools illustrated here.
Commercial Service ToolsEIS002X4
Tool number
(Kent-Moore No.)
Tool nameDescription
—
(J-39570)
Chassis earLocating the noise
—
(J-43980)
NISSAN Squeak and Rattle kitRepairing the cause of noise
SBT 8 39
SBT 8 40
Tool name
(Kent-Moore No.)Description
Engine ear
(J-39565)Locating the noise
SIIA0995E

EI-6
SQUEAK AND RATTLE TROUBLE DIAGNOSIS
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DUPLICATE THE NOISE AND TEST DRIVE
If possible, drive the vehicle with the customer until the noise is duplicated. Note any additional information on
the Diagnostic Worksheet regarding the conditions or location of the noise. This information can be used to
duplicate the same conditions when you confirm the repair.
If the noise can be duplicated easily during the test drive, to help identify the source of the noise, try to dupli-
cate the noise with the vehicle stopped by doing one or all of the following:
1. Close a door.
2. Tap or push/pull around the area where the noise appears to be coming from.
3. Rev the engine.
4. Use a floor jack to recreate vehicle “twist”.
5. At idle, apply engine load (electrical load, drive position on A/T model).
6. Raise the vehicle on a hoist and hit a tire with a rubber hammer.

Drive the vehicle and attempt to duplicate the conditions the customer states exist when the noise occurs.

If it is difficult to duplicate the noise, drive the vehicle slowly on an undulating or rough road to stress the
vehicle body.
CHECK RELATED SERVICE BULLETINS
After verifying the customer concern or symptom, check ASIST for Technical Service Bulletins (TSBs) related
to that concern or symptom.
If a TSB relates to the symptom, follow the procedure to repair the noise.
LOCATE THE NOISE AND IDENTIFY THE ROOT CAUSE
1. Narrow down the noise to a general area. To help pinpoint the source of the noise, use a listening tool
(Chassis Ear: J-39570, Engine Ear: J-39565 and mechanics stethoscope).
2. Narrow down the noise to a more specific area and identify the cause of the noise by:

Removing the components in the area that you suspect the noise is coming from.
Do not use too much force when removing clips and fasteners, otherwise clips and fasteners
can be broken or lost during the repair, resulting in the creation of new noise.

Tapping or pushing/pulling the component that you suspect is causing the noise.
Do not tap or push/pull the component with excessive force, otherwise the noise will be elimi-
nated only temporarily.

Feeling for a vibration with your hand by touching the component(s) that you suspect is (are) causing
the noise.

Placing a piece of paper between components that you suspect are causing the noise.

Looking for loose components and contact marks.
Refer to EI-7, "
Generic Squeak and Rattle Troubleshooting" .
REPAIR THE CAUSE

If the cause is a loose component, tighten the component securely.

If the cause is insufficient clearance between components:
–Separate components by repositioning or loosening and retightening the component, if possible.
–Insulate components with a suitable insulator such as urethane pads, foam blocks, felt cloth tape or ure-
thane tape. A NISSAN Squeak and Rattle Kit (J-43980) is available through your authorized NISSAN
Parts Department.
CAUTION:
Do not use excessive force as many components are constructed of plastic and may be damaged.
Always check with the Parts Department for the latest parts information.
The following materials are contained in the NISSAN Squeak and Rattle Kit (J-43980). Each item can be
ordered separately as needed.
URETHANE PADS [1.5 mm (0.059 in) thick]
Insulates connectors, harness, etc.
76268-9E005: 100 x 135 mm (3.94 x 5.31 in)/76884-71L01: 60 x 85 mm (2.36 x 3.35 in)/76884-71L02: 15 x 25
mm (0.59 x 0.98 in)
INSULATOR (Foam blocks)
Insulates components from contact. Can be used to fill space behind a panel.

EI-8
SQUEAK AND RATTLE TROUBLE DIAGNOSIS
Revision: August 20072004 QX56
Tapping or moving the components or pressing on them while driving to duplicate the conditions can isolate
many of these incidents. You can usually insulate the areas with felt cloth tape or insulator foam blocks from
the NISSAN Squeak and Rattle Kit (J-43980) to repair the noise.
TRUNK
Trunk noises are often caused by a loose jack or loose items put into the trunk by the owner.
In addition look for:
1. Trunk lid bumpers out of adjustment
2. Trunk lid striker out of adjustment
3. The trunk lid torsion bars knocking together
4. A loose license plate or bracket
Most of these incidents can be repaired by adjusting, securing or insulating the item(s) or component(s) caus-
ing the noise.
SUNROOF/HEADLINING
Noises in the sunroof/headlining area can often be traced to one of the following:
1. Sunroof lid, rail, linkage or seals making a rattle or light knocking noise
2. Sun visor shaft shaking in the holder
3. Front or rear windshield touching headliner and squeaking
Again, pressing on the components to stop the noise while duplicating the conditions can isolate most of these
incidents. Repairs usually consist of insulating with felt cloth tape.
OVERHEAD CONSOLE (FRONT AND REAR)
Overhead console noises are often caused by the console panel clips not being engaged correctly. Most of
these incidents are repaired by pushing up on the console at the clip locations until the clips engage.
In addition look for:
1. Loose harness or harness connectors.
2. Front console map/reading lamp lens loose.
3. Loose screws at console attachment points.
SEATS
When isolating seat noise it's important to note the position the seat is in and the load placed on the seat when
the noise is present. These conditions should be duplicated when verifying and isolating the cause of the
noise.
Cause of seat noise include:
1. Headrest rods and holder
2. A squeak between the seat pad cushion and frame
3. The rear seatback lock and bracket
These noises can be isolated by moving or pressing on the suspected components while duplicating the con-
ditions under which the noise occurs. Most of these incidents can be repaired by repositioning the component
or applying urethane tape to the contact area.
UNDERHOOD
Some interior noise may be caused by components under the hood or on the engine wall. The noise is then
transmitted into the passenger compartment.
Causes of transmitted underhood noise include:
1. Any component mounted to the engine wall
2. Components that pass through the engine wall
3. Engine wall mounts and connectors
4. Loose radiator mounting pins
5. Hood bumpers out of adjustment
6. Hood striker out of adjustment
These noises can be difficult to isolate since they cannot be reached from the interior of the vehicle. The best
method is to secure, move or insulate one component at a time and test drive the vehicle. Also, engine RPM
or load can be changed to isolate the noise. Repairs can usually be made by moving, adjusting, securing, or
insulating the component causing the noise.

EI-14
FRONT BUMPER
Revision: August 20072004 QX56
3. Remove engine undercover.
4. Remove fog/turn lamp finisher and fog/turn lamp.

Disconnect harnesses.
5. Remove engine underside cover.
6. Remove fasteners, release clips and remove front fascia assembly.
7. Remove plastic clips and remove upper energy absorber.
8. Remove upper bumper reinforcement.
9. Remove plastic clips and remove lower energy absorber.
10. Remove front bumper stays and front bumper side brackets, LH and RH.
INSTALLATION
Installation is in the reverse order of removal.

EM-1
ENGINE MECHANICAL
B ENGINE
CONTENTS
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SECTION EM
A
EM
Revision: August 20072004 QX56 PRECAUTIONS .......................................................... 3
Precautions for Drain Engine Coolant ...................... 3
Precautions for Disconnecting Fuel Piping .............. 3
Precautions for Removal and Disassembly ............. 3
Precautions for Inspection, Repair and Replace-
ment ......................................................................... 3
Precautions for Assembly and Installation ............... 3
Parts Requiring Angular Tightening ......................... 3
Precautions for Liquid Gasket .................................. 4
REMOVAL OF LIQUID GASKET SEALING .......... 4
LIQUID GASKET APPLICATION PROCEDURE ..... 4
PREPARATION ........................................................... 5
Special Service Tools ............................................... 5
Commercial Service Tools ........................................ 7
NOISE, VIBRATION, AND HARSHNESS (NVH)
TROUBLESHOOTING ................................................ 9
NVH Troubleshooting —Engine Noise ..................... 9
Use the Chart Below to Help You Find the Cause
of the Symptom. ..................................................... 10
ENGINE ROOM COVER ...........................................11
Removal and Installation .........................................11
REMOVAL ............................................................11
INSTALLATION ....................................................11
DRIVE BELTS ........................................................... 12
Checking Drive Belts .............................................. 12
Tension Adjustment ................................................ 12
Removal and Installation ........................................ 12
DRIVE BELT ....................................................... 12
INSTALLATION ................................................... 13
Drive Belt Auto Tensioner and Idler Pulley ............. 13
REMOVAL ........................................................... 13
INSTALLATION ................................................... 13
AIR CLEANER AND AIR DUCT ............................... 14
Removal and Installation ........................................ 14
REMOVAL ........................................................... 14
INSTALLATION ................................................... 14
CHANGING AIR CLEANER FILTER ................... 14INTAKE MANIFOLD ................................................. 15
Removal and Installation ........................................ 15
REMOVAL ........................................................... 15
INSTALLATION ................................................... 17
INSPECTION AFTER INSTALLATION ................ 18
EXHAUST MANIFOLD AND THREE WAY CATA-
LYST .......................................................................... 19
Removal and Installation ........................................ 19
REMOVAL ........................................................... 19
INSPECTION AFTER REMOVAL ....................... 20
INSTALLATION ................................................... 20
OIL PAN AND OIL STRAINER ................................. 22
Removal and Installation ........................................ 22
REMOVAL ........................................................... 22
INSPECTION AFTER REMOVAL ....................... 23
INSTALLATION ................................................... 24
INSPECTION AFTER INSTALLATION ................ 25
IGNITION COIL ......................................................... 26
Removal and Installation ........................................ 26
REMOVAL ........................................................... 26
INSTALLATION ................................................... 26
SPARK PLUG (PLATINUM-TIPPED TYPE) ............. 27
Removal and Installation ........................................ 27
REMOVAL ........................................................... 27
INSPECTION AFTER REMOVAL ....................... 27
INSTALLATION ................................................... 28
FUEL INJECTOR AND FUEL TUBE ........................ 29
Removal and Installation ........................................ 29
REMOVAL ........................................................... 29
INSTALLATION ................................................... 30
INSPECTION AFTER INSTALLATION ................ 32
ROCKER COVER ..................................................... 33
Removal and Installation ........................................ 33
REMOVAL ........................................................... 33
INSTALLATION ................................................... 34
TIMING CHAIN .......................................................... 35
Removal and Installation ........................................ 35
REMOVAL ........................................................... 36
INSPECTION AFTER REMOVAL ....................... 39
INSTALLATION ................................................... 39

EM-2Revision: August 20072004 QX56 CAMSHAFT ............................................................... 43
Removal and Installation ........................................ 43
REMOVAL ........................................................... 43
INSPECTION AFTER REMOVAL ........................ 47
INSTALLATION .................................................... 49
Valve Clearance ...................................................... 52
INSPECTION ....................................................... 52
ADJUSTMENT .................................................... 54
OIL SEAL .................................................................. 56
Removal and Installation of Valve Oil Seal ............. 56
REMOVAL ........................................................... 56
INSTALLATION .................................................... 56
Removal and Installation of Front Oil Seal ............. 57
REMOVAL ........................................................... 57
INSTALLATION .................................................... 57
Removal and Installation of Rear Oil Seal .............. 57
REMOVAL ........................................................... 57
INSTALLATION .................................................... 58
CYLINDER HEAD ..................................................... 59
On-Vehicle Service ................................................. 59
CHECKING COMPRESSION PRESSURE ......... 59
Removal and Installation ........................................ 60
REMOVAL ........................................................... 60
INSPECTION AFTER REMOVAL ........................ 61
INSTALLATION .................................................... 61
Disassembly and Assembly .................................... 62
DISASSEMBLY ................................................... 62
ASSEMBLY ......................................................... 63
Inspection After Disassembly ................................. 64
CYLINDER HEAD DISTORTION ........................ 64
VALVE DIMENSIONS .......................................... 65
VALVE GUIDE CLEARANCE .............................. 66
VALVE GUIDE REPLACEMENT ......................... 66
VALVE SEAT CONTACT ..................................... 68
VALVE SEAT REPLACEMENT ........................... 68
VALVE SPRING SQUARENESS ......................... 69
VALVE SPRING DIMENSIONS AND VALVE
SPRING PRESSURE LOAD ............................... 69
ENGINE ASSEMBLY ................................................ 70
Removal and Installation ........................................ 70
REMOVAL ........................................................... 70
INSTALLATION .................................................... 71
INSPECTION AFTER INSTALLATION ................ 72
CYLINDER BLOCK ................................................... 73
Disassembly and Assembly .................................... 73
DISASSEMBLY ................................................... 74ASSEMBLY ..........................................................77
How to Select Piston and Bearing ..........................82
DESCRIPTION ....................................................82
HOW TO SELECT PISTON .................................83
HOW TO SELECT CONNECTING ROD BEAR-
ING .......................................................................84
HOW TO SELECT MAIN BEARING ....................85
Inspection After Disassembly ..................................89
CRANKSHAFT END PLAY ..................................89
CONNECTING ROD SIDE CLEARANCE ...........89
PISTON AND PISTON PIN CLEARANCE ...........89
PISTON RING SIDE CLEARANCE .....................90
PISTON RING END GAP ....................................90
CONNECTING ROD BEND AND TORSION .......91
CONNECTING ROD BEARING (BIG END) ........91
CONNECTING ROD BUSHING OIL CLEAR-
ANCE (SMALL END) ...........................................91
CYLINDER BLOCK DISTORTION ......................92
MAIN BEARING HOUSING INSIDE DIAMETER ...93
PISTON TO CYLINDER BORE CLEARANCE ....93
CRANKSHAFT JOURNAL DIAMETER ...............94
CRANKSHAFT PIN DIAMETER ..........................95
OUT-OF-ROUND AND TAPER OF CRANK-
SHAFT .................................................................95
CRANKSHAFT RUNOUT ....................................95
CONNECTING ROD BEARING OIL CLEAR-
ANCE ...................................................................95
MAIN BEARING OIL CLEARANCE .....................96
CRUSH HEIGHT OF MAIN BEARING ................97
CRUSH HEIGHT OF CONNECTING ROD
BEARING .............................................................97
MAIN BEARING CAP BOLT DIAMETER .............97
CONNECTING ROD BOLT DIAMETER ..............98
SERVICE DATA AND SPECIFICATIONS (SDS) ......99
Standard and Limit ..................................................99
GENERAL SPECIFICATIONS .............................99
DRIVE BELTS ......................................................99
EXHAUST MANIFOLD ........................................99
CAMSHAFT AND CAMSHAFT BEARING ......... 100
CYLINDER HEAD .............................................. 102
CYLINDER BLOCK ............................................ 104
PISTON, PISTON RING AND PISTON PIN ...... 105
CONNECTING ROD .......................................... 105
CRANKSHAFT ................................................... 106
MAIN BEARING ................................................. 107