2011 INFINITI QX56 engine coolant

COMPONENT PARTSEC-17
< SYSTEM DESCRIPTION > [VK56VD]
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EXHAUST COMPARTMENT
1. VVEL actuator motor (bank 2) 2. Ignition coil (with power transistor)
and spark plug (bank 2)3. Camshaft position sensor (bank 2)
4. High pressure fuel pump 5. Intake valve timing control solenoid valve (bank 2)6. Electric-viscous fan assembly
7. Engine oil temperature sensor 8. Intake valve timing control solenoid valve (bank 1)9. Camshaft position sensor (bank 1)
10. Ignition coil (with power transistor) and spark plug (bank 1) 11. VVEL actuator motor (bank 1) 12. Low fuel pressure sensor
13. Positive crankcase ventilation (PCV) valve 14. Fuel injector (bank 2) 15. Knock sensor (bank 2)
16. Knock sensor (bank 1) 17. Fuel injector (bank 1) 18. Fuel rail pressure sensor
19. Manifold absolute pressure sensor 20. VVEL control shaft position sensor (bank 1)21. Crankshaft position sensor
22. Engine coolant temperature sensor 23. VVEL control shaft position sensor (bank 2)
A. Top view of the engine (View with intake manifold is re-
moved) B. Rear view of the engine
:Engine front
JPBIA3972ZZ
Revision: 2010 May2011 QX56

COMPONENT PARTSEC-19
< SYSTEM DESCRIPTION > [VK56VD]
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Component DescriptionINFOID:0000000006217657
1. ASCD steering switch
ICC steering switch 2. Snow mode switch 3. Fuel level sensor unit and fuel pump
assembly (with fuel tank temperature
sensor)
4. Fuel pump control module (FPCM) 5. EVAP canister vent control valve 6. EVAP canister
7. EVAP control system pressure sen- sor 8. Stop lamp switch 9. ASCD brake switch
ICC brake switch
10. Accelerator pedal position sensor
JSBIA0606ZZ
Component Reference
ECM EC-23, "
ECM"
Malfunction indicator lamp (MIL)EC-30, "Malfunction Indicator Lamp (MIL)"
Ignition coil with power transistorEC-29, "Ignition Coil With Power Transistor"
Accelerator pedal position sensorEC-21, "Accelerator Pedal Position Sensor"
Mass air flow sensor
EC-31, "Mass Air Flow Sensor (With Intake Air Temperature Sen-
sor)"Intake air temperature sensor
Electric throttle control actuator
EC-23, "
Electric Throttle Control Actuator"Throttle control motor relay
Throttle control motor
Throttle position sensor
Crankshaft position sensorEC-23, "
Crankshaft Position Sensor"
Camshaft position sensorEC-22, "Camshaft Position Sensor"
Engine coolant temperature sensorEC-25, "Engine Coolant Temperature Sensor"
Revision: 2010 May2011 QX56

COMPONENT PARTSEC-25
< SYSTEM DESCRIPTION > [VK56VD]
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OEngine Coolant Temperature SensorINFOID:0000000006217669
The engine coolant temperature (ECT
) sensor is used to detect the
engine coolant temperature. The sensor modifies a voltage signal
from the ECM. The modified signal returns to the ECM as the engine
coolant temperature input. The sens or uses a thermistor which is
sensitive to the change in temperature. The electrical resistance of
the thermistor decreases as temperature increases.

*: These data are reference values and are measured between ECM terminals.
Engine Oil Temperature SensorINFOID:0000000006217670
The engine oil temperature sensor is used to detect the engine oil
temperature. The sensor modifies a voltage signal from the ECM.
The modified signal returns to the ECM as the engine oil tempera-
ture input. The sensor uses a ther mistor which is sensitive to the
change in temperature. The electrical resistance of the thermistor
decreases as temperature increases.

*: These data are reference values and are measured between ECM terminals. 1. Valve 2. Armature 3. Magnet Loop Element
4. Fan speed sensor 5. Coil 6. Silicon oil
SEF594K
Engine coolant temperature
[° C ( °F)] Voltage* (V) Resistance (k
Ω)
− 10 (14) 4.4 7.0 - 11.4
20 (68) 3.5 2.35 - 2.73
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
SEF012P
SEF594K
Engine oil temperature [° C ( °F)] Voltage* (V) Resistance (k
Ω)
–10 (14) 4.4 7.0 - 11.4 20 (68) 3.5 2.35 - 2.73
50 (122) 2.2 0.68 - 1.00
90 (194) 0.9 0.236 - 0.260
110 (230) 0.6 0.143 - 0.153
SEF012P
Revision: 2010 May2011 QX56

EC-28
< SYSTEM DESCRIPTION >[VK56VD]
COMPONENT PARTS
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of
the air fuel ratio (A/F) sensor 1
are shifted, the air fuel ratio is c ontrolled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1 V in richer conditions to 0 V in leaner con-
ditions.
Under normal conditions the heated ox ygen sensor 2 is not used for
engine control operation.
HEATED OXYGEN SENSOR 2 HEATER
Heated oxygen sensor 2 heater is integrated in the sensor.
The ECM performs ON/OFF control of the heated oxy gen sensor 2 heater corresponding to the engine speed,
amount of intake air and engine coolant temperature.
High Pressure Fuel PumpINFOID:0000000006217678
The high pressure fuel pump is installed at the front of the engine bank 2 side and activated by the camshaft.
ECM controls the high pressure fuel pump control sol enoid valve built into the high pressure fuel pump and
adjusts the amount of discharge by changing the suction timing of the low pressure fuel.
Operating Description
SEF327R
Engine speed Heated oxygen sensor 2 heater
Above 3,600 rpm OFF
Below 3,600 rpm after the following conditions are met.
 Engine: After warming up
 Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and at idle for 1 minute under no load ON
JSBIA0285GB
Revision: 2010 May2011 QX56

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*1: This sensor is not used to control the engine system under normal conditions.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
The adoption of the direct fuel injection method enables
more accurate adjustment of fuel injection quantity by
injecting atomized high-pressure fuel directly into the cylinder. This method allows high-powered engine, low
fuel consumption, and emissions-reduction.
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). T he amount of fuel injected is a program value in the
ECM memory. The program value is preset by engi ne operating conditions. These conditions are determined
by input signals (for engine speed and intake air and fuel rail pressure) from the crankshaft position sensor,
camshaft position sensor, mass air flow sensor and the fuel rail pressure sensor.
VARIOUS FUEL INJECTION INCREASE/DECREASE COMPENSATION
In addition, the amount of fuel injected is compens ated to improve engine performance under various operat-
ing conditions as listed below.
 During warm-up
 When starting the engine
 During acceleration
 Hot-engine operation
 When selector lever position is changed from N to D
 High-load, high-speed operation

 During deceleration
 During high engine speed operation
FUEL INJECTION CONTROL
Stratified-charge Combustion
Stratified-charge combustion is a combustion method wh ich enables extremely lean combustion by injecting
fuel in the latter half of a compression process, coll ecting combustible air-fuel around the spark plug, and form-
ing fuel-free airspace around the mixture.
Right after a start with the engine cold, the catalyst warm-up is accelerated by stratified-charge combustion.
Homogeneous Combustion
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor Engine speed*
2
Fuel injection
& mixture ratio
controlFuel injector
Camshaft position sensor Camshaft position
Mass air flow sensor Amount of intake air
Intake air temperature sensor Intake air temperature
Engine coolant temperature sensor Engine coolant temperature
Air fuel ratio (A/F) sensor 1 Density of oxygen in exhaust gas
Fuel rail pressure sensor Fuel rail pressure
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
TCM Gear position
Battery
Battery voltage*
2
Knock sensor Engine knocking condition
Power steering pressure sensor Power steering operation
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit) VDC/TCS operation command
A/C auto amp. A/C ON signal
Combination meter Vehicle speed
Revision: 2010 May2011 QX56

EC-38
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
Homogeneous combustion is a combustion method that fuel
is injected during intake process so that combus-
tion occurs in the entire combustion chamber , as is common with conventional methods.
As for a start except for starts with the engine cold, homogeneous combustion occurs.
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)
The mixture ratio feedback system prov ides the best air-fuel mixture ratio for driveability and emission control.
The three way catalyst (manifold) can better reduce CO , HC and NOx emissions. This system uses A/F sen-
sor 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 A/F sensor 1, refer to
EC-21, "
Air Fuel Ratio (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 th ree way catalyst (manifold). Even if the switching
characteristics of 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 t he mixture ratio signal transmitted from A/F sensor 1.
This feedback signal is then sent to the ECM. The ECM c ontrols the basic mixture ratio as close to the theoret-
ical mixture ratio as possible. However, the basic mi xture ratio is not necessarily controlled as originally
designed. Both manufacturing differences (i.e., mass ai r flow sensor hot wire) and characteristic changes dur-
ing operation (i.e., fuel 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 co mpared 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 compensati on 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 carri ed out over time to compensate for continual deviation
of the “short-term fuel trim” from the central value. Continual deviation will occur due to individual engine differ-
ences, wear over time and changes in the usage environment.
FUEL INJECTION TIMING
Sequential Direct Injection Gasoline System
PBIB2793E
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SYSTEMEC-39
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Fuel is injected into each cylinder during each engine cycle accord-
ing to the ignition order.
STRATIFIED-CHARGE START CONTROL
The use of the stratified-charge combustion met
hod enables emissions-reduction when starting the engine
with engine coolant temperature between 5 °C (41 °F) and 40 °C (104 °F).
FUEL SHUT-OFF
Fuel to each cylinder is shut-off during deceleration, operation of the engine at excessively high speed or oper-
ation of the vehicle at excessively high speed.
FUEL PRESSURE CONTROL
FUEL PRESSURE CONTROL : System DiagramINFOID:0000000006217701
FUEL PRESSURE CONTROL : System DescriptionINFOID:0000000006217702
INPUT/OUTPUT SIGNAL CHART
JSBIA0407GB
JSBIA0315GB
Sensor Input signal to ECM ECM function Actuator
Crankshaft position sensor Engine speed
Fuel injection
& mixture ratio
controlHigh pressure fuel pump
Camshaft position sensor Camshaft position
Fuel rail pressure sensor Fuel rail pressure
Low fuel pressure sensor Low fuel pressure
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Battery Battery voltage
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EC-40
< SYSTEM DESCRIPTION >[VK56VD]
SYSTEM
SYSTEM DESCRIPTION
Low fuel pressure control
 The low fuel pressure pump is controlled by the f
uel pump control module (FPCM) and pumps fuel according
to a driving condition. The pumped fuel passes through t he fuel filter and is sent to the high pressure fuel
pump. FPCM controls the low pressure fuel pump, ac cording to a signal from ECM as shown in the table
below.
 Low fuel pressure is adjusted by the fuel pressure regulator.
High fuel pressure control
 The high pressure fuel pump raises the pressure of the fuel sent from the low pressure fuel pump. Actuated
by the camshaft, the high pressure fuel pump activates the high pressure fuel pump solenoid based on a sig-
nal received from ECM, and adjusts the amount of di scharge by changing the timing of closing the inlet
check valve to control fuel rail pressure.
COOLING FAN CONTROL
JSBIA0235GB
Conditions Amount of fuel flow Supplied voltage
After a laps of 1 second after ignition ON OFF 0 V
 For 1 second after turning ignition switch ON
 Engine is running under low load and low speed conditions Low Approximately 8.5 V
 Engine cranking
 Engine coolant temperature is below 10 °C (50 °F)
 Engine is running under high load and high speed conditions High
Battery voltage
(11 – 14 V)
Except the above Mid Approximately 10 V
Revision: 2010 May2011 QX56