sensor INFINITI QX4 2005 Factory Service Manual

EC-24Revision: October 2005
ENGINE CONTROL SYSTEM
2005 QX56
Multiport Fuel Injection (MFI) SystemUBS00KZ7
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This signal is sent to the ECM through CAN communication line.
*3: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compensated to improve engine performance under various operat-
ing conditions as listed below.
<Fuel increase>

During warm-up

When starting the engine

During acceleration

Hot-engine operation

When selector lever is changed from N to D

High-load, high-speed operation
<Fuel decrease>

During deceleration

During high engine speed operation
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
3
Piston position
Fuel injection
& mixture ratio
controlFuel injector Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/neutral position (PNP) switch Gear position
Knock sensor Engine knocking condition
Battery
Battery voltage*
3
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit)*
2VDC/TCS operation command
Air conditioner switch*
2Air conditioner operation
Wheel sensor*
2Vehicle speed

ENGINE CONTROL SYSTEM
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MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can then better reduce CO, HC and NOx emissions. This system uses air
fuel ratio (A/F) sensor 1 in the exhaust manifold to monitor whether the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about air
fuel ratio (A/F) sensor 1, refer to EC-459, "
DTC P1271, P1281 A/F SENSOR 1" . This maintains the mixture
ratio within the range of stoichiometric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 is located downstream of the three way catalyst (manifold). Even if the switching
characteristics of air fuel ratio (A/F) sensor 1 shift, the air-fuel ratio is controlled to stoichiometric by the signal
from heated oxygen sensor 2.
Open Loop Control
The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.

Deceleration and acceleration

High-load, high-speed operation

Malfunction of A/F sensor 1 or its circuit

Insufficient activation of A/F sensor 1 at low engine coolant temperature

High engine coolant temperature

During warm-up

After shifting from N to D

When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mixture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This is
then computed in terms of “injection pulse duration” to automatically compensate for the difference between
the two ratios.
“Fuel trim” refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
“Short term fuel trim” is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from A/F sensor 1 indicates whether the mixture ratio is RICH or LEAN compared to the the-
oretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is rich, and an increase in
fuel volume if it is lean.
“Long term fuel trim” is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
SEF 5 03 YB

EC-26Revision: October 2005
ENGINE CONTROL SYSTEM
2005 QX56
FUEL INJECTION TIMING
Two types of systems are used.
Sequential Multiport Fuel Injection System
Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
FUEL SHUT-OFF
Fuel to each cylinder is cut off during deceleration, operation of the engine at excessively high speeds or oper-
ation of the vehicle at excessively high speed.
Electronic Ignition (EI) SystemUBS00KZ8
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Firing order: 1 - 8 - 7 - 3 - 6 - 5 - 4 -2
The ignition timing is controlled by the ECM to maintain the best air-fuel ratio for every running condition of the
engine. The ignition timing data is stored in the ECM.
The ECM receives information such as the injection pulse width and camshaft position sensor signal. Comput-
ing this information, ignition signals are transmitted to the power transistor.
During the following conditions, the ignition timing is revised by the ECM according to the other data stored in
the ECM.

At starting

During warm-up

At idle

At low battery voltage
PBIB0122E
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
controlPower transistor Camshaft position sensor (PHASE)
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery
Battery voltage*
2
Wheel sensor*1Vehicle speed

ENGINE CONTROL SYSTEM
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During acceleration
The knock sensor retard system is designed only for emergencies. The basic ignition timing is programmed
within the anti-knocking zone, if recommended fuel is used under dry conditions. The retard system does not
operate under normal driving conditions. If engine knocking occurs, the knock sensor monitors the condition.
The signal is transmitted to the ECM. The ECM retards the ignition timing to eliminate the knocking condition.
Fuel Cut Control (at No Load and High Engine Speed)UBS00KZ9
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM through CAN communication line.
SYSTEM DESCRIPTION
If the engine speed is above 1,800 rpm under no load (for example, the shift position is neutral and engine
speed over is 1,800 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off varies
based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under EC-24, "
Multiport Fuel Injection (MFI) System" .
Sensor Input signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut con-
trolFuel injector Accelerator pedal position sensor Accelerator pedal position
Engine coolant temperature sensor Engine coolant temperature
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed
Wheel sensor* Vehicle speed

EC-28Revision: October 2005
AIR CONDITIONING CUT CONTROL
2005 QX56
AIR CONDITIONING CUT CONTROLPFP:23710
Input/Output Signal ChartUBS00KZA
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
System DescriptionUBS00KZB
This system improves engine operation when the air conditioner is used.
Under the following conditions, the air conditioner is turned OFF.

When the accelerator pedal is fully depressed.

When cranking the engine.

At high engine speeds.

When the engine coolant temperature becomes excessively high.

When operating power steering during low engine speed or low vehicle speed.

When engine speed is excessively low.

When refrigerant pressure is excessively low or high.
Sensor Input Signal to ECM ECM function Actuator
Air conditioner switch*
1Air conditioner ON signal
Air conditioner
cut controlAir conditioner relay Accelerator pedal position sensor Accelerator pedal position
Crankshaft position sensor (POS)
Camshaft position sensor (PHASE)Engine speed*
2
Engine coolant temperature sensor Engine coolant temperature
Battery
Battery voltage*
2
Refrigerant pressure sensor Refrigerant pressure
Power steering pressure sensor Power steering operation
Wheel sensor*
1Vehicle speed

AUTOMATIC SPEED CONTROL DEVICE (ASCD)
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Revision: October 20052005 QX56
AUTOMATIC SPEED CONTROL DEVICE (ASCD)PFP:18930
System DescriptionUBS00KZC
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 depressing 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.
NOTE:
Always drive vehicle in safe manner according to traffic conditions and obey all traffic laws.
SET OPERATION
Press 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 SET/COAST switch. (Then SET indicator in combination meter illuminates.)
ACCEL OPERATION
If the RESUME/ACCELERATE 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 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 SET/COAST switch or RESUME/
ACCELERATE switch.

Malfunction for some self-diagnoses regarding ASCD control: SET lamp will blink quickly.
If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
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
Wheel sensor* Vehicle speed
TCM* Powertrain revolution

EVAPORATIVE EMISSION SYSTEM
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Revision: October 20052005 QX56
Component InspectionUBS00KZG
EVAP CANISTER
Check EVAP canister as follows:
1. Block port B .
2. Blow air into port A and check that it flows freely out of port C .
3. Release blocked port B .
4. Apply vacuum pressure to port B and check that vacuum pres-
sure exists at the ports A and C .
5. Block port A and B .
6. Apply pressure to port C and check that there is no leakage.
FUEL TANK VACUUM RELIEF VALVE (BUILT INTO FUEL FULLER CAP)
1. Wipe clean valve housing.
2. Check valve opening pressure and vacuum.
3. If out of specification, replace fuel filler cap as an assembly.
CAUTION:
Use only a genuine fuel filler cap as a replacement. If an incor-
rect fuel filler cap is used, the MIL may come on.
EVAP CANISTER PURGE VOLUME CONTROL SOLENOID VALVE
Refer to EC-318 and EC-531 .
FUEL TANK TEMPERATURE SENSOR
Refer to EC-253 and EC-259 .
EVAP CANISTER VENT CONTROL VALVE
Refer to EC-325 and EC-539 .
EVAP CONTROL SYSTEM PRESSURE SENSOR
Refer to EC-332 , EC-335 and EC-341 .
PBIB1212E
SEF 4 45 Y
Pressure:
15.3 - 20.0 kPa (0.156 - 0.204 kg/cm2 , 2.22
- 2.90 psi)
Va c u u m :
−6.0 to −3.3 kPa (−0.061 to −0.034 kg/cm
2 ,
−0.87 to −0.48 psi)
SEF 9 43 S

EC-40Revision: October 2005
ON BOARD REFUELING VAPOR RECOVERY (ORVR)
2005 QX56
Diagnostic ProcedureUBS00KZK
SYMPTOM: FUEL ODOR FROM EVAP CANISTER IS STRONG.
1. CHECK EVAP CANISTER
1. Remove EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
2. Weigh the EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
The weight should be less than 2.5 kg (5.5 lb).
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2. CHECK IF EVAP CANISTER SATURATED WITH WATER
Does water drain from the EVAP canister?
Ye s o r N o
Yes >> GO TO 3.
No >> GO TO 5.
3. REPLACE EVAP CANISTER
Replace EVAP canister with a new one.
>> GO TO 4.
4. DETECT MALFUNCTIONING PART
Check the EVAP hose between EVAP canister and vehicle frame for clogging or poor connection.
>> Repair or replace EVAP hose.
5. CHECK REFUELING EVAP VAPOR CUT VALVE
Refer to EC-43, "
Component Inspection" .
OK or NG
OK >>INSPECTION END
NG >> Replace refueling EVAP vapor cut valve with fuel tank.
BBIA0351E

ON BOARD REFUELING VAPOR RECOVERY (ORVR)
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SYMPTOM: CANNOT REFUEL/FUEL ODOR FROM THE FUEL FILLER OPENING IS STRONG
WHILE REFUELING.
1. CHECK EVAP CANISTER
1. Remove EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
2. Weigh the EVAP canister with EVAP canister vent control valve and EVAP control system pressure sensor
attached.
The weight should be less than 2.5 kg (5.5 lb).
OK or NG
OK >> GO TO 2.
NG >> GO TO 3.
2. CHECK IF EVAP CANISTER SATURATED WITH WATER
Does water drain from the EVAP canister?
Ye s o r N o
Yes >> GO TO 3.
No >> GO TO 5.
3. REPLACE EVAP CANISTER
Replace EVAP canister with a new one.
>> GO TO 4.
4. DETECT MALFUNCTIONING PART
Check the EVAP hose between EVAP canister and vehicle frame for clogging or poor connection.
>> Repair or replace EVAP hose.
5. CHECK VENT HOSES AND VENT TUBES
Check hoses and tubes between EVAP canister and refueling EVAP vapor cut valve for clogging, kink, loose-
ness and improper connection.
OK or NG
OK >> GO TO 6.
NG >> Repair or replace hoses and tubes.
6. CHECK FILLER NECK TUBE
Check recirculation line for clogging, dents and cracks.
OK or NG
OK >> GO TO 7.
NG >> Replace filler neck tube.
BBIA0351E

EC-48Revision: October 2005
ON BOARD DIAGNOSTIC (OBD) SYSTEM
2005 QX56
ON BOARD DIAGNOSTIC (OBD) SYSTEMPFP:00028
IntroductionUBS00KZP
The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actua-
tors. The ECM also records various emission-related diagnostic information including:
The above information can be checked using procedures listed in the table below.
×: Applicable —: Not applicable
*: When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.
The malfunction indicator lamp (MIL) on the instrument panel lights up when the same malfunction is detected
in two consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode. (Refer to EC-103,
"Fail-safe Chart" .)
Two Trip Detection LogicUBS00KZQ
When a malfunction is detected for the first time, 1st trip DTC and 1st trip Freeze Frame data are stored in the
ECM memory. The MIL will not light up at this stage. <1st trip>
If the same malfunction is detected again during the next drive, the DTC and Freeze Frame data are stored in
the ECM memory, and the MIL lights up. The MIL lights up at the same time when the DTC is stored. <2nd
trip> The “trip” in the “Two Trip Detection Logic” means a driving mode in which self-diagnosis is performed
during vehicle operation. Specific on board diagnostic items will cause the ECM to light up or blink the MIL,
and store DTC and Freeze Frame data, even in the 1st trip, as shown below.
×: Applicable —: Not applicable
When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting up MIL when there is
malfunction on engine control system.
Emission-related diagnostic information Diagnostic service
Diagnostic Trouble Code (DTC) Service $03 of SAE J1979
Freeze Frame data Service $02 of SAE J1979
System Readiness Test (SRT) code Service $01 of SAE J1979
1st Trip Diagnostic Trouble Code (1st Trip DTC) Service $07 of SAE J1979
1st Trip Freeze Frame data
Test values and Test limits Service $06 of SAE J1979
Calibration ID Service $09 of SAE J1979
DTC 1st trip DTCFreeze
Frame data1st trip Freeze
Frame dataSRT code SRT status Test value
CONSULT-II×× × × × ×—
GST×× ×—×××
ECM××*— — —×—
ItemsMIL DTC 1st trip DTC
1st trip 2nd trip
1st trip
displaying2nd trip
displaying1st trip
displaying2nd trip
display-
ing BlinkingLighting
upBlinkingLighting
up
Misfire (Possible three way cata-
lyst damage) — DTC: P0300 -
P0308 is being detected×———— —×—
Misfire (Possible three way cata-
lyst damage) — DTC: P0300 -
P0308 is being detected——×——×——
One trip detection diagnoses
(Refer to EC-49, "
EMISSION-
RELATED DIAGNOSTIC INFOR-
MATION ITEMS" .)—×——×———
Except above — — —×—××—