2001 INFINITI QX4 Fuel

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
IGN TIMING [BTDC]qIIndicates the ignition timing computed
by ECM according to the input signals.IWhen the engine is stopped, a certain
value is indicated.
IACV-AAC/V [step]qIIndicates the IACV-AAC valve control
value computed by ECM according to
the input signals.
PURG VOL C/V [%]IIndicates the EVAP canister purge vol-
ume control solenoid valve control
value computed by the ECM according
to the input signals.
IThe opening becomes larger as the
value increases.
A/F ALPHA-B1 [%]q
IThe mean value of the air-fuel ratio
feedback correction factor per cycle is
indicated.IWhen the engine is stopped, a certain
value is indicated.
IThis data also includes the data for the
air-fuel ratio learning control. A/F ALPHA-B2 [%]q
AIR COND RLY
[ON/OFF]qIThe air conditioner relay control condi-
tion (determined by ECM according to
the input signal) is indicated.
FUEL PUMP RLY
[ON/OFF]qIIndicates the fuel pump relay control
condition determined by ECM accord-
ing to the input signals.
VENT CONT/V
[ON/OFF]IThe control condition of the EVAP can-
ister vent control valve (determined by
ECM according to the input signal) is
indicated.
ION ... Closed
OFF ... Open
HO2S1 HTR (B1)
[ON/OFF]IIndicates [ON/OFF] condition of front
heated oxygen sensor heater deter-
mined by ECM according to the input
signals. HO2S1 HTR (B2)
[ON/OFF]
HO2S2 HTR (B1)
[ON/OFF]IIndicates [ON/OFF] condition of rear
heated oxygen sensor heater deter-
mined by ECM according to the input
signals. HO2S2 HTR (B2)
[ON/OFF]
VC/V BYPASS/V
[ON/OFF]IThe control condition of the vacuum cut
valve bypass valve (determined by
ECM according to the input signal) is
indicated.
ION ... Open
OFF ... Closed
CAL/LD VALUE [%]IªCalculated load valueº indicates the
value of the current airflow divided by
peak airflow.
ABSOL TH´P/S [%]IªAbsolute throttle position sensorº indi-
cates the throttle opening computed by
ECM according to the signal voltage of
the throttle position sensor.
MASS AIRFLOW
[g´m/s]IIndicates the mass airflow computed by
ECM according to the signal voltage of
the mass airflow sensor.GI
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-89

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
INT/V TIM (B1) [ÉCA]
IIndicate [ÉCA] of intake camshaft
advanced angle.
INT/V TIM (B2) [ÉCA]
INT/V SOL (B1) [%]IThe control condition of the intake
valve timing control solenoid valve is
indicated. INT/V SOL (B2) [%]
TRVL AFTER MIL
[km] or [Mile]IDistance traveled while MIL is activated
VIAS S/V
[ON/OFF]IThe control condition of the VIAS con-
trol solenoid valve (determined by ECM
according to the input signal) is indi-
cated.
IOFF ... VIAS control solenoid valve is
not operating.
ON ... VIAS control solenoid valve is
operating.
SWL CON VC SWIIndicates [ON/OFF] condition from the
swirl control valve control vacuum
check switch.
ON ... Swirl control valve is not opera-
tional.
OFF ... Swirl control valve is opera-
tional.
IDL A/V LEANIDisplay the condition of idle air volume
learning
YET ... Idle air volume learning has not
been performed yet.
CMPLT ... Idle air volume learning has
already been performed successfully.
INCMP ... Idle air volume learning has
not been performed successfully.
Voltage [V]IVoltage measured by the voltage
probe.
Frequency
[msec] or [Hz] or [%]IPulse width, frequency or duty cycle
measured by the pulse probe.IOnly ª#º is displayed if item is unable to
be measured.
IFigures with ª#ºs are temporary ones.
They are the same figures as an actual
piece of data which was just previously
measured.
NOTE:
IAny monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
IRegarding R50 model, ª-B1º indicates right bank and ª-B2º indicates left bank.
IBank 1 (-B1 or BK1) includes No. 1 cylinder.
DATA MONITOR (SPEC) MODENBEC0034S11
Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
MAS A/F SE-B1 [V]qqIThe signal voltage of the mass air flow sen-
sor specification is displayed.IWhen the engine is running, specifi-
cation range is indicated.
B/FUEL SCHDL
[msec]IªBase fuel scheduleº indicates the fuel injec-
tion pulse width programmed into ECM,
prior to any learned on board correction.IWhen the engine is running, specifi-
cation range is indicated.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-90

Monitored item [Unit]ECM
input
signalsMain
signalsDescription Remarks
A/F ALPHA-B1 [%]q
IIndicates the mean value of the air-fuel ratio
feedback correction factor per cycle.IWhen the engine is running, specifi-
cation range is indicated.
IThis data also includes the data for
the air-fuel ratio learning control. A/F ALPHA-B2 [%]q
NOTE:
IAny monitored item that does not match the vehicle being diagnosed is deleted from the display automatically.
IRegarding R50 model, ªB1º indicates bank 1 and ªB2º indicates bank 2.
ACTIVE TEST MODENBEC0034S07
TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL INJECTIONIEngine: Return to the original
trouble condition
IChange the amount of fuel injec-
tion using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.IHarness and connector
IFuel injectors
IHeated oxygen sensor
IGNITION TIMINGIEngine: Return to the original
trouble condition
ITiming light: Set
IRetard the ignition timing using
CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.IAdjust initial ignition timing
IACV-AAC/V
OPENINGIEngine: After warming up, idle
the engine.
IChange the IACV-AAC valve
opening percent using CON-
SULT-II.Engine speed changes according
to the opening percent.IHarness and connector
IIACV-AAC valve
POWER BAL-
ANCEIEngine: After warming up, idle
the engine.
IA/C switch ªOFFº
IShift lever ªNº
ICut off each injector signal one
at a time using CONSULT-II.Engine runs rough or dies.IHarness and connector
ICompression
IInjectors
IPower transistor
ISpark plugs
IIgnition coils
ENG COOLANT
TEMPIEngine: Return to the original
trouble condition
IChange the engine coolant tem-
perature using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.IHarness and connector
IEngine coolant temperature sen-
sor
IFuel injectors
FUEL PUMP
RELAYIIgnition switch: ON
(Engine stopped)
ITurn the fuel pump relay ªONº
and ªOFFº using CONSULT-II
and listen to operating sound.Fuel pump relay makes the operat-
ing sound.IHarness and connector
IFuel pump relay
VIAS SOL VALVEIIgnition switch: ON
ITurn solenoid valve ªONº and
ªOFFº with CONSULT-II and lis-
ten for operating sound.Solenoid valve makes an operating
sound.IHarness and connector
ISolenoid valve
SWIRL CONT
S O L VA LV EIIgnition switch: ON
ITurn solenoid valve ªONº and
ªOFFº with CONSULT-II and lis-
ten for operating sound.Solenoid valve makes an operating
sound.IHarness and connector
ISolenoid valve
PURG VOL
CONT/VIEngine: After warming up, run
engine at 1,500 rpm.
IChange the EVAP canister purge
volume control solenoid valve
opening percent using CON-
SULT-II.Engine speed changes according
to the opening percent.IHarness and connector
ISolenoid valve
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ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-91

TEST ITEM CONDITION JUDGEMENT CHECK ITEM (REMEDY)
FUEL/T TEMP
SENIChange the fuel tank temperature using CONSULT-II.
VENT
CONTROL/VIIgnition switch: ON
(Engine stopped)
ITurn solenoid valve ªONº and
ªOFFº with the CONSULT-II and
listen to operating sound.Solenoid valve makes an operating
sound.IHarness and connector
ISolenoid valve
VC/V BYPASS/VIIgnition switch: ON
(Engine stopped)
ITurn solenoid valve ªONº and
ªOFFº with the CONSULT-II and
listen to operating sound.Solenoid valve makes an operating
sound.IHarness and connector
ISolenoid valve
TARGET INT/V
TIMIEngine: After warming up, hold
engine speed at 1,500 to 2,000
rpm.
IChange the intake valve timing
using CONSULT-II.If trouble symptom disappears, see
CHECK ITEM.IHarness and connector
IIntake valve timing control sole-
noid valve
DTC & SRT CONFIRMATION MODENBEC0034S08SRT STATUS ModeNBEC0034S0801For details, refer to ªSYSTEM READINESS TEST (SRT) CODEº,
EC-61.
SRT Work Support ModeNBEC0034S0803This mode enables a technician to drive a vehicle to set the SRT
while monitoring the SRT status.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
CONSULT-II (Cont'd)
EC-92

FUNCTIONNBEC0035S03
Diagnostic test mode Function
MODE 1 READINESS TESTSThis mode gains access to current emission-related data values, including analog
inputs and outputs, digital inputs and outputs, and system status information.
MODE 2 (FREEZE DATA)This mode gains access to emission-related data value which were stored by ECM
during the freeze frame. [For details, refer to ªFreeze Frame Dataº (EC-85).]
MODE 3 DTCsThis mode gains access to emission-related power train trouble codes which were
stored by ECM.
MODE 4 CLEAR DIAG INFOThis mode can clear all emission-related diagnostic information. This includes:
IClear number of diagnostic trouble codes (MODE 1)
IClear diagnostic trouble codes (MODE 3)
IClear trouble code for freeze frame data (MODE 1)
IClear freeze frame data (MODE 2)
IReset status of system monitoring test (MODE 1)
IClear on board monitoring test results (MODE 6 and 7)
MODE 6 (ON BOARD TESTS)This mode accesses the results of on board diagnostic monitoring tests of specific
components/systems that are not continuously monitored.
MODE 7 (ON BOARD TESTS)This mode enables the off board test drive to obtain test results for emission-related
powertrain components/systems that are continuously monitored during normal driving
conditions.
MODE 8 ÐThis mode can close EVAP system in ignition switch ªONº position (Engine stopped).
When this mode is performed, the following parts can be opened or closed.
IEVAP canister vent control valve open
IVacuum cut valve bypass valve closed
In the following conditions, this mode cannot function.
ILow ambient temperature
ILow battery voltage
IEngine running
IIgnition switch ªOFFº
ILow fuel temperature
IToo much pressure is applied to EVAP system
MODE 9 (CALIBRATION ID)This mode enables the off-board test device to request specific vehicle information
such as Vehicle Identification Number (VIN) and Calibration IDs.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
Generic Scan Tool (GST) (Cont'd)
EC-96

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

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