Nissan Pathfinder (2012 year). Instruction — part 303
ENGINE CONTROL SYSTEM
EC-505
< SYSTEM DESCRIPTION >
[VK56DE]
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1.
ASCD steering switch
2.
MAIN switch
3.
CANCEL switch
4.
SET/COAST switch
5.
RESUME/ACCELERATE switch
6.
ECM harness connectors (view with
ECM cover removed)
7.
Coolant reservoir
8.
Accelerator pedal position sensor
9.
Fuel level sensor unit and fuel pump
harness connector (view with fuel
tank removed)
AWBIA0084ZZ
August 2012
2012 Pathfinder
EC-506
< SYSTEM DESCRIPTION >
[VK56DE]
ENGINE CONTROL SYSTEM
10. Fuel pump, fuel level sensor unit and
fuel filter
11. Fuel pressure regulator
12. ASCD brake switch
13. Stop lamp switch
14. Brake pedal
August 2012
2012 Pathfinder
MULTIPORT FUEL INJECTION SYSTEM
EC-507
< SYSTEM DESCRIPTION >
[VK56DE]
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MULTIPORT FUEL INJECTION SYSTEM
System Description
INFOID:0000000007358425
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 via the 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 the crankshaft position sensor, the camshaft 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 position 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
control
Fuel 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
Knock sensor
Engine knocking condition
Battery
Battery voltage*
3
Power steering pressure sensor
Power steering operation
Heated oxygen sensor 2*
1
Density of oxygen in exhaust gas
ABS actuator and electric unit (control unit)
VDC/TCS operation command*
2
Air conditioner switch
Air conditioner operation*
2
Unified meter control unit
Gear position
Vehicle speed*
2
August 2012
2012 Pathfinder
EC-508
< SYSTEM DESCRIPTION >
[VK56DE]
MULTIPORT FUEL INJECTION SYSTEM
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 A/F
sensor 1, refer to
EC-676, "Component Description"
. This maintains the mixture ratio within the range of sto-
ichiometric (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 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 overtime 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.
PBIB3020E
August 2012
2012 Pathfinder
MULTIPORT FUEL INJECTION SYSTEM
EC-509
< SYSTEM DESCRIPTION >
[VK56DE]
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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 ignition order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
Fuel is injected simultaneously into all 8 cylinders twice each engine cycle. In other words, pulse signals of the
same width are simultaneously transmitted from the ECM.
The 8 fuel injectors will then receive the signals 2 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.
PBIB0122E
August 2012
2012 Pathfinder
EC-510
< SYSTEM DESCRIPTION >
[VK56DE]
ELECTRIC IGNITION SYSTEM
ELECTRIC IGNITION SYSTEM
System Description
INFOID:0000000007358426
INPUT/OUTPUT SIGNAL CHART
*1: This signal is sent to the ECM via the CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
SYSTEM DESCRIPTION
Ignition 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
• 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.
Sensor
Input signal to ECM
ECM function
Actuator
Crankshaft position sensor (POS)
Engine speed*
2
Piston position
Ignition timing
control
Power 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
Battery
Battery voltage*
2
Unified meter control unit
Gear position
Vehicle speed*
1
August 2012
2012 Pathfinder
AIR CONDITIONING CUT CONTROL
EC-511
< SYSTEM DESCRIPTION >
[VK56DE]
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AIR CONDITIONING CUT CONTROL
Input/Output Signal Chart
INFOID:0000000007358427
*1: This signal is sent to the ECM via the CAN communication line.
*2: ECM determines the start signal status by the signals of engine speed and battery voltage.
System Description
INFOID:0000000007358428
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
Air conditioner ON signal*
1
Air conditioner
cut control
Air 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
Unified meter control unit
Vehicle speed*
1
August 2012
2012 Pathfinder
EC-512
< SYSTEM DESCRIPTION >
[VK56DE]
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
AUTOMATIC SPEED CONTROL DEVICE (ASCD)
System Description
INFOID:0000000007358429
INPUT/OUTPUT SIGNAL CHART
*: This signal is sent to the ECM via the CAN communication line
BASIC ASCD SYSTEM
Refer to Owner's Instruction 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 on combination meter. If any
malfunction occurs in ASCD system, CRUISE indicator blinks and ASCD control is deactivated.
NOTE:
Always drive vehicle in a safe manner according to traffic conditions and obey all traffic laws.
SET OPERATION
Press MAIN switch. (The CRUISE indicator on 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 on combination meter illuminates.)
ACCELERATE 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 maintain 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 position 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 CRUISE indicator.
• Engine coolant temperature is slightly higher than the normal operating temperature, CRUISE indicator may
blink slowly.
When the engine coolant temperature decreases to the normal operating temperature, CRUISE indicator 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 indicator will blink quickly.
If MAIN switch is turned to OFF while ASCD is activated, all of ASCD operations will be canceled and vehicle
speed memory will be erased.
COAST OPERATION
When the SET/COAST switch is pressed during cruise control driving, decrease vehicle set speed until the
switch is released. And then ASCD will maintain the new set speed.
RESUME OPERATION
Sensor
Input signal to ECM
ECM function
Actuator
ASCD brake switch
Brake pedal operation
ASCD vehicle speed control
Electric throttle control
actuator
Stop lamp switch
Brake pedal operation
ASCD steering switch
ASCD steering switch operation
Unified meter control unit
Gear position
Vehicle speed*
TCM
Powertrain revolution*
August 2012
2012 Pathfinder
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