2001 INFINITI QX4 Ac system

23 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 28.
NG©GO TO 24.
24 REPLACE IACV-AAC VALVE
Replace IACV-AAC valve.
©GO TO 25.
25 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-57.
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 26.
INCMP©1. Follow the construction of ªIdle Air Volume Learningº.
2. GO TO 22.
26 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 28.
NG©GO TO 27.
27 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function. (ECM may be the cause of a problem, but this is rarely
the case.)
2. Perform initialization of IVIS (NATS) system and registration of IVIS (NATS) ignition key IDs. Refer to ªIVIS (INFINITI
VEHICLE IMMOBILIZER SYSTEM Ð NATS)º, EC-74.
©GO TO 22.
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-113

31 PERFORM IDLE AIR VOLUME LEARNING
Refer to ªIdle Air Volume Learningº, EC-57.
Which is the result CMPLT or INCMP?
CMPLT or INCMP
CMPLT©GO TO 32.
INCMP©1. Follow the construction of ªIdle Air volume Learningº.
2. GO TO 31.
32 CHECK TARGET IDLE SPEED AGAIN
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªENG SPEEDº in ªDATA MONITORº mode with CONSULT-II.
3. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Check idle speed.
750±50 rpm (in ªPº or ªNº position)
OK or NG
OK©GO TO 34.
NG©GO TO 33.
33 CHECK ECM FUNCTION
1. Substitute another known-good ECM to check ECM function.
(ECM may be the cause of a problem, but this is rarely the case.)
2. Perform initialization of NVIS (NATS) system and registration of NVIS (NATS) ignition key IDs. Refer to ªNVIS (NISSAN
VEHICLE IMMOBILIZER SYSTEM Ð NATS)º, EC-74.
©GO TO 31.
34 CHECK IGNITION TIMING AGAIN
Check ignition timing again. Refer to Test No. 30.
OK or NG
OK©GO TO 36.
NG©GO TO 35.
35 CHECK TIMING CHAIN INSTALLATION
Check timing chain installation. Refer to EM-29, ªInstallationº.
OK or NG
OK©GO TO 33.
NG©1. Repair the timing chain installation.
2. GO TO 31.
36 ERASE UNNECESSARY DTC
After this inspection, unnecessary DTC No. might be displayed.
Erase the stored memory in ECM and TCM (Transmission control module).
Refer to ªHow to Erase Emission-Related Diagnostic Informationº, EC-72 and AT-35, ªHOW TO ERASE DTCº.
©INSPECTION END
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TROUBLE DIAGNOSIS Ð BASIC INSPECTION
Basic Inspection (Cont'd)
EC-115

DTC Inspection Priority ChartNBEC0039If some DTCs are displayed at the same time, perform inspections one by one based on the following prior-
ity chart.
Priority Detected items (DTC)
1IP0100 Mass air flow sensor
IP0110 Intake air temperature sensor
IP0115 P0125 Engine coolant temperature sensor
IP0120 Throttle position sensor
IP0180 Fuel tank temperature sensor
IP0325 Knock sensor
IP0335 P1336 Crankshaft position sensor (POS)
IP0340 Camshaft position sensor (PHASE)
IP0460 P0461 P0464 P1464 Fuel level sensor
IP0500 Vehicle speed sensor
IP0605 ECM
IP1320 Ignition signal
IP1335 Crankshaft position sensor (REF)
IP1605 A/T diagnosis communication line
IP1706 Park/Neutral position (PNP) switch
2IP0105 Absolute pressure sensor
IP0130-P0134, P0150-P0154 Heated oxygen sensor 1 (front)
IP0135 P0155 Heated oxygen sensor 1 heater (front)
IP0137-P0140, P0157-P0160 Heated oxygen sensor 2 (rear)
IP0141 P0161 Heated oxygen sensor 2 (rear) heater
IP0217 Coolant overtemperature enrichment protection
IP0443 P1444 EVAP canister purge volume control solenoid valve
IP0446 P1446 P1448 EVAP canister vent control valve
IP0450 EVAP control system pressure sensor
IP0510 Closed throttle position switch
IP0705-P0755 P1705 P1760 A/T related sensors, solenoid valves and switches
IP 1111Intake valve timing control solenoid valve
IP1140 Intake valve timing control position sensor
IP1165 Swirl control valve control vacuum check switch
IP1441 EVAP control system (VERY SMALL LEAK)
IP1447 EVAP control system purge flow monitoring
IP1490 P1491 Vacuum cut valve bypass valve
3IP0171 P0172 P0174 P0175 Fuel injection system function
IP0306 - P0300 Misfire
IP0420 P0430 Three way catalyst function
IP0440 P1440 EVAP control system (SMALL LEAK)
IP0455 EVAP control system (GROSS LEAK)
IP0505 IACV-AAC valve
IP0600 A/T communication line
IP0731-P0734 P0744 A/T function
IP1110 Intake valve timing control
IP1130 Swirl control valve control solenoid valve
IP1148 P1168 Closed loop control
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
DTC Inspection Priority Chart
EC-116

Fail-safe Chart=NBEC0040The ECM enters fail-safe mode, if any of the following malfunctions is detected due to the open or short cir-
cuit. When the ECM enters the fail-safe mode, the MIL illuminates.
DTC No. Detected items Engine operating condition in fail-safe mode
P0100 Mass air flow sensor circuit Engine speed will not rise more than 2,400 rpm due to the fuel cut.
P0115 Engine coolant temperature
sensor circuitEngine coolant temperature will be determined by ECM based on the time after
turning ignition switch ªONº or ªSTARTº.
CONSULT-II displays the engine coolant temperature decided by ECM.
ConditionEngine coolant temperature decided
(CONSULT-II display)
Just as ignition switch is turned
ON or Start40ÉC (104ÉF)
More than approx. 4 minutes
after ignition ON or Start80ÉC (176ÉF)
Except as shown above40 - 80ÉC (104 - 176ÉF)
(Depends on the time)
P0120 Throttle position sensor cir-
cuitThrottle position will be determined based on the injected fuel amount and the
engine speed.
Therefore, acceleration will be poor.
Condition Driving condition
When engine is idling Normal
When accelerating Poor acceleration
P1335 Crankshaft position sensor
(REF) circuitCompression TDC signal (120É signal) is controlled by camshaft position sensor
(PHASE) signal and crankshaft position sensor (POS) signal. Ignition timing will be
delayed 0É to 2É.
Unable to
access ECMECMECM fail-safe activating condition
The computing function of the ECM was judged to be malfunctioning.
When the fail-safe system activates (i.e., if the ECM detects a malfunction condi-
tion in the CPU of ECM), the MIL on the instrument panel lights to warn the driver.
However it is not possible to access ECM and DTC cannot be confirmed.
Engine control with fail-safe
When ECM fail-safe is operating, fuel injection, ignition timing, fuel pump operation,
IACV-AAC valve operation and cooling fan operation are controlled under certain
limitations.
ECM fail-safe operation
Engine speedEngine speed will not rise more than 3,000
rpm
Fuel injection Simultaneous multiport fuel injection system
Ignition timing Ignition timing is fixed at the preset valve
Fuel pumpFuel pump relay is ªONº when engine is running
and ªOFFº when engine stalls
IACV-AAC valve Full open
Replace ECM, if ECM fail-safe condition is confirmed.
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Fail-safe Chart
EC-117

Symptom Matrix ChartNBEC0041SYSTEM Ð BASIC ENGINE CONTROL SYSTEMNBEC0041S01
SYMPTOM
Reference
page
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Fuel Fuel pump circuit11232 2 2 3 2EC-625
Fuel pressure regulator system3344444 4 4 4EC-40
Injector circuit11232 2 2 2EC-616
Evaporative emission system
3344444 4 4 4EC-32
Air Positive crankcase ventilation sys-
tem1 EC-38
Incorrect idle speed adjustment 1 1 1 1 1 EC-101
IACV-AAC valve circuit1123322 2 2 2 2EC-422
Ignition Incorrect ignition timing adjustment33111 1 1 1EC-101
Ignition circuit 1 1 2 2 2 2 2 2 EC-499
Main power supply and ground circuit
22333 3 32
3EC-142
Air conditioner circuit 3 3 2 HA section
1 - 6: The numbers refer to the order of inspection.
(continued on next page)
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Matrix Chart
EC-118

SYSTEM Ð ENGINE MECHANICAL & OTHERNBEC0041S02
SYMPTOM
Reference
section
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
Fuel Fuel tank
5
5FE section
Fuel piping 5 5 5 5 5 5
Ð Vapor lock
Valve deposit
5 555 5 5 5
Poor fuel (Heavy weight gasoline,
Low octane)
Air Air duct
55555 5 Air cleaner
Air leakage from air duct
(Mass air flow sensor Ð throttle
body)
555 5
Throttle body, Throttle wireFE section
Air leakage from intake manifold/
Collector/GasketÐ
Cranking Battery
111111 11
EL section Alternator circuit
Starter circuit 3
Flywheel/Drive plate 6 EM section
PNP switch 4 AT section
1 - 6: The numbers refer to the order of inspection.
(continued on next page)
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Matrix Chart (Cont'd)
EC-120

SYMPTOM
Reference
section
HARD/NO START/RESTART (EXCP. HA)
ENGINE STALL
HESITATION/SURGING/FLAT SPOT
SPARK KNOCK/DETONATION
LACK OF POWER/POOR ACCELERATION
HIGH IDLE/LOW IDLE
ROUGH IDLE/HUNTING
IDLING VIBRATION
SLOW/NO RETURN TO IDLE
OVERHEATS/WATER TEMPERATURE HIGH
EXCESSIVE FUEL CONSUMPTION
EXCESSIVE OIL CONSUMPTION
BATTERY DEAD (UNDER CHARGE)
Warranty symptom code AA AB AC AD AE AF AG AH AJ AK AL AM HA
IVIS (INFINITI Vehicle Immobilizer System Ð
NATS)11EC-74 or EL
section
1 - 6: The numbers refer to the order of inspection.
CONSULT-II Reference Value in Data Monitor
Mode
NBEC0042Remarks:
ISpecification data are reference values.
ISpecification data are output/input values which are detected or supplied by the ECM at the connector.
* Specification data may not be directly related to their components signals/values/operations.
i.e. Adjust ignition timing with a timing light before monitoring IGN TIMING, because the monitor may show the specification data in
spite of the ignition timing not being adjusted to the specification data. This IGN TIMING monitors the data calculated by the ECM
according to the signals input from the camshaft position sensor and other ignition timing related sensors.
IIf the real-time diagnosis results are NG and the on board diagnostic system results are OK when diagnosing the mass air flow sensor,
first check to see if the fuel pump control circuit is normal.
MONITOR ITEM CONDITION SPECIFICATION
ENG SPEED
CKPS´RPM (POS)ITachometer: Connect
IRun engine and compare tachometer indication with the CONSULT-II
value.Almost the same speed as
the CONSULT-II value.
POS COUNTIEngine: Running 179 - 181
MAS A/F SE-B1IEngine: After warming up
IAir conditioner switch: ªOFFº
IShift lever: ªNº
INo-loadIdle 1.2 - 1.8V
2,500 rpm 1.6 - 2.2V
COOLAN TEMP/SIEngine: After warming up More than 70ÉC (158ÉF)
HO2S1 (B1)
HO2S1 (B2)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,Approx. 0.6 -
1.0V
HO2S1 MNTR (B1)
HO2S1 MNTR (B2)LEAN+,RICH
Changes more than 5 times
during 10 seconds.
HO2S2 (B1)
HO2S2 (B2)
IEngine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V+,Approx. 0.6 -
1.0V
HO2S2 MNTR (B1)
HO2S2 MNTR (B2)LEAN+,RICH
TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
Symptom Matrix Chart (Cont'd)
EC-122

TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
71 OR/LHeated oxygen sensor
2 (rear) (bank 2)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
72 ORHeated oxygen sensor
2 (rear) (bank 1)[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.0 - Approximately 1.0V
73 B/PMass air flow sensor
ground[Engine is running]
IWarm-up condition
IIdle speedApproximately 0V
79 Y/GIntake valve timing
control position sen-
sors (RH)[Engine is running]
IWarm-up condition
IIdle speedApproximately 0.5V
SEF351Z
[Engine is running]
IWarm-up condition
IEngine speed is 2,000 rpm.Approximatley 0.5V
SEF352Z
80 L/RAbsolute pressure sen-
sor[Ignition switch ªONº]Approximately 4.4V
81 W/PURefrigerant pressure
sensor[Engine is running]
IWarm-up condition
IBoth A/C switch and blower switch are ªONº.
(Compressor operates.)0.36 - 3.88V
82 WThrottle position sensor
signal output[Engine is running]
IWarm-up condition
IAccelerator pedal fully releasedApproximately 0.4V
[Ignition switch ªONº]
IAccelerator pedal fully depressedApproximately 4V
83 Y/PU Fuel level sensor[Ignition switch ªONº]Approximately 0 - 4.8V
Output voltage varies with
fuel level.
84 L/GEVAP control system
pressure sensor[Ignition switch ªONº]Approximately 3.4V
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TROUBLE DIAGNOSIS Ð GENERAL DESCRIPTION
ECM Terminals and Reference Value (Cont'd)
EC-133