NISSAN LATIO 2010 Service Repair Manual

EC-36
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MULTIPORT FUEL INJECTION SYSTEM
MULTIPORT FUEL INJECTION SYSTEM
System DiagramINFOID:0000000005398252
System DescriptionINFOID:0000000005398253
INPUT/OUTPUT SIGNAL CHART
*1: This sensor is not used to control the engine system under normal conditions.
JMBIA2193GB
Sensor
Input signal to ECMECM functionActuator
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
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
Throttle position sensor Throttle position
Accelerator pedal position sensor Accelerator pedal position
Park/neutral position (PNP) switch (M/T)
Transmission range switch (A/T) Gear position
Battery Battery voltage*
3
Knock sensorEngine knocking condition
Heated oxygen sensor 2*
1Density of oxygen in exhaust gas
EPS control unit Power steering operation*
2
ABS actuator and electric unit (control unit)
Vehicle speed*2
Combination meter
BCMAir conditioner ON signal*
2
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*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). T he 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 t he crankshaft position sensor (POS), camshaft position
sensor (PHASE) 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.

• During warm-up
• When starting the engine
• During acceleration
• Hot-engine operation
• When selector lever is changed from N to D (A/T models)
• High-load, high-speed operation

• During deceleration
• During high engine speed operation
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 si gnal. For more information about A/F sensor 1, refer to
EC-176, "
Description". This maintains the mixture ratio within t he range of stoichiometric (ideal air-fuel mix-
ture).
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 rati o is controlled to stoichiometric by the signal from heated
oxygen sensor 2.
• Open Loop Control
The open loop system condition refers to when the EC M 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 (A/T models)
- 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 mi xture ratio is not necessarily controlled as originally
PBIB2793E
Revision: January 20102010 Versa

EC-38
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MULTIPORT FUEL INJECTION SYSTEM
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 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 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
Two types of systems are used.
• Sequential Multiport Fuel Injection System Fuel is injected into each cylinder during each engine cy cle 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 four cylinder s twice each engine cycle. In other words, pulse signals
of the same width are simultaneously transmitted from the ECM.
The four 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 speeds.
SEF337W
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Component Parts LocationINFOID:0000000005398254
1. Ignition coil (with power transistor)
and spark plug 2. Intake valve timing control solenoid
valve 3. Refrigerant pressure sensor
4. Knock sensor 5. Fuel injector6. Cooling fan motor
7. Camshaft position sensor (PHASE) 8. IPDM E/R 9. ECM
10. Mass air flow sensor (with intake air temperature sensor) 11. Engine coolant temperature sensor 12. Electric throttle control actuator
(with built in throttle position sensor
and throttle control motor)
13. EVAP canister purge volume control solenoid valve
PBIB2939E
Revision: January 20102010 Versa

EC-40
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MULTIPORT FUEL INJECTION SYSTEM
1. Mass air flow sensor
(with intake air temperature sensor) 2. Engine coolant temperature sensor 3. Electric throttle control actuator
4. Camshaft position sensor (PHASE) 5. Ignition coil (with power transistor) 6. Fuel injector
7. EVAP canister purge volume control solenoid valve
Vehicle front
PBIB2940E
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MULTIPORT FUEL INJECTION SYSTEMEC-41
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1. ECM harness connectors
2. ECM3. IPDM E/R
4. Fuel pump fuse (15A) 5. Intake valve timing control solenoid
valve 6. Knock sensor
7. Refrigerant pressure sensor 8. PCV valve Vehicle front
PBIB2941E
Revision: January 20102010 Versa

EC-42
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MULTIPORT FUEL INJECTION SYSTEM
1. Air fuel ratio (A/F) sensor 1 2. Three way catalyst (Manifold) 3. Heated oxygen sensor 2
4. Three way catalyst (Under floor) 5. Muffler
Vehicle front
1. Exhaust manifold 2. Air fuel ratio (A/F) sensor 1 3. Heated oxygen sensor 2
4. Heated oxygen sensor 2 harness connector
Vehicle front
JMBIA2192ZZ
PBIB2943E
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MULTIPORT FUEL INJECTION SYSTEMEC-43
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Component DescriptionINFOID:0000000005398255
1. Cooling fan motor harness connec-
tor 2. Crankshaft position sensor 3. Stop lamp switch
4. Brake pedal 5. Accelerator pedal position sensor
harness connector 6. Accelerator pedal position sensor
7. Accelerator pedal 8. Fuel level sensor unit and fuel pump
harness connector (view with in-
spection hole cover removed) 9. Fuel pressure regulator
10. Fuel pump
AWBIA0044ZZ
Component Reference
A/F sensor 1 EC-176, "
Description"
Accelerator pedal position sensorEC-392, "Description"
Camshaft position sensor (PHASE)EC-262, "Description"
Crankshaft position sensor (POS)EC-257, "Description"
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EC-44
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MULTIPORT FUEL INJECTION SYSTEM
Engine coolant temperature sensor
EC-161, "Description"
Fuel injectorEC-423, "Description"
Heated oxygen sensor 2EC-198, "Description"
Intake air temperature sensorEC-156, "Description"
Knock sensorEC-253, "Description"
Mass air flow sensorEC-142, "Description"
Throttle position sensorEC-165, "Description"
Component Reference
Revision: January 20102010 Versa

ELECTRIC IGNITION SYSTEMEC-45
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ELECTRIC IGNITION SYSTEM
System DiagramINFOID:0000000005398256
System DescriptionINFOID:0000000005398257
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 - 3 - 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 injecti
on pulse width and camshaft position sensor (PHASE) sig-
nal. Computing this information, ignition si gnals are transmitted to the power transistor.
During the following conditions, the ignition timing is revi sed 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
JMBIA2194GB
Sensor Input signal to ECMECM functionActuator
Crankshaft position sensor (POS) Engine speed*
2
Piston position
Ignition timing
controlIgnition coil (with 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
Battery Battery voltage*
2
Knock sensorEngine knocking
Park/neutral position (PNP) switch (M/T)
Transmission range switch (A/T) Gear position
ABS actuator and electric unit (control unit) Vehicle speed*
1Combination meter
Revision: January 20102010 Versa