spark plugs replace INFINITI QX4 2001 Factory Service Manual

MEF036D
IntroductionNBEC0036
SEF233G
SEF234G
The engine has an ECM to control major systems such as fuel
control, ignition control, idle air control system, etc. The ECM
accepts input signals from sensors and instantly drives actuators.
It is essential that both input and output signals are proper and
stable. At the same time, it is important that there are no problems
such as vacuum leaks, fouled spark plugs, or other problems with
the engine.
It is much more difficult to diagnose a problem that occurs intermit-
tently rather than continuously. Most intermittent problems are
caused by poor electric connections or improper wiring. In this
case, careful checking of suspected circuits may help prevent the
replacement of good parts.
A visual check only may not find the cause of the problems. A road
test with CONSULT-II (or GST) or a circuit tester connected should
be performed. Follow the ªWork Flowº on EC-99.
Before undertaking actual checks, take a few minutes to talk with
a customer who approaches with a driveability complaint. The cus-
tomer can supply good information about such problems, espe-
cially intermittent ones. Find out what symptoms are present and
under what conditions they occur. A ªDiagnostic Worksheetº like the
example on next page should be used.
Start your diagnosis by looking for ªconventionalº problems first.
This will help troubleshoot driveability problems on an electronically
controlled engine vehicle.
SEF907L
DIAGNOSTIC WORKSHEETNBEC0036S01There are many operating conditions that lead to the malfunction
of engine components. A good grasp of such conditions can make
trouble-shooting faster and more accurate.
In general, each customer feels differently about a problem. It is
important to fully understand the symptoms or conditions for a
customer complaint.
Utilize a diagnostic worksheet like the one on the next page in order
to organize all the information for troubleshooting.
Some conditions may cause the MIL to come on steady or blink and
DTC to be detected. Examples:
IVehicle ran out of fuel, which caused the engine to misfire.
IFuel filler cap was left off or incorrectly screwed on, allowing
fuel to evaporate into the atmosphere.
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TROUBLE DIAGNOSIS Ð INTRODUCTION
Introduction
EC-97

5 CHECK IGNITION SPARK
1. Disconnect ignition wire from spark plug.
2. Connect a known good spark plug to the ignition wire.
3. Place end of spark plug against a suitable ground and crank engine.
4. Check for spark.
SEF575Q
OK or NG
OK©GO TO 6.
NG©Check ignition coil, power transistor and their circuits. Refer to ªDTC P1320 IGNITION
SIGNALº, EC-499
6 CHECK SPARK PLUGS
Remove the spark plugs and check for fouling, etc.
SEF156I
OK or NG
OK©GO TO 7.
NG©Repair or replace spark plug(s) with standard type one(s). For spark plug type, refer to
MA-13, ªENGINE MAINTENANCEº.
7 CHECK COMPRESSION PRESSURE
Check compression pressure. Refer to EM-14, ªMeasurement of Compression Pressureº.
Standard:
1,275 kPa (13.0 kg/cm
2, 185 psi)/300 rpm
Minimum:
981 kPa (10.0 kg/cm
2, 142 psi)/300 rpm
Difference between each cylinder:
98 kPa (1.0 kg/cm
2, 14 psi)/300 rpm
OK or NG
OK©GO TO 8.
NG©Check pistons, piston rings, valves, valve seats and cylinder head gaskets.
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DTC P0300 - P0306 NO.6-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
Diagnostic Procedure (Cont'd)
EC-323

NBEM0007
SEM480G
SEM481G
JEM482G
SEM387C
1. Warm up engine.
2. Turn ignition switch OFF.
3. Release fuel pressure.
Refer to EC-39, ªFuel Pressure Releaseº.
4. Remove engine cover and throttle wire.
5. Remove air duct with air cleaner case.
6. Remove harness connectors and harness brackets around
ignition coils.
7. Remove throttle body.
8. Disconnect ignition coil with power transistor harness
connectors, then remove ignition coils.
9. Remove all spark plugs.
IClean area around plug with compressed air before removing
the spark plug.
10. Attach a compression tester to No. 1 cylinder.
11. Depress accelerator pedal fully to keep throttle valve wide
open.
12. Crank engine and record highest gauge indication.
13. Repeat the measurement on each cylinder as shown above.
IAlways use a fully-charged battery to obtain specified
engine speed.
Unit: kPa (kg/cm2, psi)/rpm
Standard MinimumDifference limit between
cylinders
1,275 (13.0, 185)/300 981 (10.0, 142)/300 98 (1.0, 14)/300
14. If compression in one or more cylinders is low:
a. Pour a small amount of engine oil into cylinders through spark
plug holes.
b. Retest compression.
IIf adding oil helps compression, piston rings may be worn
or damaged. If so, replace piston rings after checking pis-
ton.
IIf pressure stays low, a valve may be sticking or seating
improperly. Inspect and repair valve and valve seat. (Refer
to SDS, EM-76 and EM-79.) If valve or valve seat is dam-
aged excessively, replace them.
IIf compression stays low in two cylinders that are next to
each other:
a) The cylinder head gasket may be leaking, or
b) Both cylinders may have valve component damage. Inspect
and repair as necessary.
15. Install parts in reverse order of removal.
16. Perform ªSelf-diagnosis Procedureº referring to EC-72, ªHow to
Erase DTCº if any DTC appears.
MEASUREMENT OF COMPRESSION PRESSURE
EM-14

Schedule 1NBMA0004S01EMISSION CONTROL SYSTEM MAINTENANCENBMA0004S0101
Abbreviations: R = Replace. I = Inspect. Correct or replace if necessary. [ ]: At the mileage intervals only
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Reference
Section
- Page or
- Content Title Perform at number of miles, kilo-
meters or months, whichever
comes first.Miles x 1,000
(km x 1,000)
Months3.75
(6)
37.5
(12)
611.25
(18)
915
(24)
1218.75
(30)
1522.5
(36)
1826.25
(42)
2130
(48)
2433.75
(54)
2737.5
(60)
3041.25
(66)
3345
(72)
3648.75
(78)
3952.5
(84)
4256.25
(90)
4560
(96)
48
Drive beltsI* I* MA-13
Air cleaner filter NOTE (1) [R] [R] MA-17
EVAP vapor linesI* I* MA-20
Fuel linesI* I* MA-16
Fuel filter* NOTE (2)MA-16
Engine coolant NOTE (3)R* MA-14
Engine oil RRRRRRRRRRRRRRRRMA-18
Engine oil filter (Use part No.
15208-31U00 or equivalent.)RRRRRRRRRRRRRRRRMA-18
Spark plugs (PLATINUM-TIPPED
type)Replace every 105,000 miles (169,000 km) MA-19
Intake & exhaust valve clearance* NOTE (4)EM-52, ªValve
Clearanceº
NOTE:
(1) If operating mainly in dusty conditions, more frequent maintenance may be required.
(2) When the filter becomes clogged, the vehicle speed cannot be increased as the driver wishes. In such an event, replace the filter.
(3) After 60,000 miles (96,000 km) or 48 months, replace every 30,000 miles (48,000 km) or 24 months.
(4) If valve noise increases, inspect valve clearance.
HMaintenance items and intervals with ª*º are recommended by INFINITI for reliable vehicle operation. The owner need not perform such maintenance in order to maintain the
emission warranty or manufacturer recall liability. Other maintenance items and intervals are required.
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PERIODIC MAINTENANCE
Schedule 1
MA-7

Schedule 2NBMA0004S02EMISSION CONTROL SYSTEM MAINTENANCENBMA0004S0201
Abbreviations: R = Replace. I = Inspect. Correct or replace if necessary. [ ]: At the mileage intervals only
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Reference Section
- Page
or
- Content Title Perform at number of miles, kilometers
or months, whichever comes first.Miles x 1,000
(km x 1,000)
Months7.5
(12)
615
(24)
1222.5
(36)
1830
(48)
2437.5
(60)
3045
(72)
3652.5
(84)
4260
(96)
48
Drive beltsI* I* MA-13
Air cleaner filter[R] [R] MA-17
EVAP vapor linesI* I* MA-20
Fuel linesI* I* MA-16
Fuel filter* NOTE (1)MA-16
Engine coolant NOTE (2)R* MA-14
Engine oilRRRRRRRRMA-18
Engine oil filter (Use part No. 15208-
31U00 or equivalent.)RRRRRRRRMA-18
Spark plugs (PLATINUM-TIPPED type) Replace every 105,000 miles (169,000 km) MA-19
Intake & exhaust valve clearance* NOTE (3)EM-52, ªValve Clear-
anceº
NOTE:
(1) When the filter becomes clogged, the vehicle speed cannot be increased as the driver wishes. In such an event, replace the filter.
(2) After 60,000 miles (96,000 km) or 48 months, replace every 30,000 miles (48,000 km) or 24 months.
(3) If valve noise increases, inspect valve clearance.
HMaintenance items and intervals with ª*º are recommended by INFINITI for reliable vehicle operation. The owner need not perform such maintenance in order to maintain the
emission warranty or manufacturer recall liability. Other maintenance items and intervals are required.
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PERIODIC MAINTENANCE
Schedule 2
MA-9