2009 NISSAN LATIO Service Repair Manual

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Page 1873 of 4331

NISSAN LATIO 2009 Service Repair Manual PREPARATION
EC-517
< SERVICE INFOMATION >
[MR TYPE 1] C
D E
F
G H
I
J
K L
M A EC
NP
O
Fuel filler cap adapter
i.e.: (MLR-8382) Checking fuel tank vacuum relief valve opening
pressure
Socket wrench Re

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Page 1875 of 4331

NISSAN LATIO 2009 Service Repair Manual EC
NP
O
*1: This sensor is not used to control the engine system under normal conditions.
*2: This signal is sent to the ECM through CAN communication line.
*3: ECM determines the start signal status

EC
NP
O
*1: This sensor is not used to control the engine system under normal conditions.
*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). 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) 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 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 is changed from N to D (A/T and CVT models)
• High-load, high-speed operation

• During deceleration
• During high engine speed operation
MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL) 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
Park/neutral position (PNP) switch Gear position
Battery Battery voltage*3
Knock sensor Engine knocking condition
EPS control unit Power steering operation*2
Heated oxygen sensor 2* 1
Density of oxygen in exhaust gas
Air conditioner switch Air conditioner operation*2
ABS actuator and electric unit (control unit) Vehicle speed*2
Combination meter

Page 1876 of 4331

NISSAN LATIO 2009 Service Repair Manual EC-520< SERVICE INFOMATION >
[MR TYPE 1]
ENGINE CONTROL SYSTEM
The mixture ratio feedback system provides the best air/ fuel mixture ratio for driveability and emission control.
The three way catal

EC-520< SERVICE INFOMATION >
[MR TYPE 1]
ENGINE CONTROL SYSTEM
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 r educe 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 t he sensor voltage signal. For more information about air
fuel ratio (A/F) sensor 1, refer to EC-698 . 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 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 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 air fuel ratio (A/F) sensor 1 or its circuit
• Insufficient activation of air fuel ratio (A /F) sensor 1 at low engine coolant temperature
• High engine coolant temperature
• During warm-up
• After shifting from N to D (A/T and CVT models)
• When starting the engine
MIXTURE RATIO SELF-LEARNING CONTROL
The mixture ratio feedback control system monitors the mixt ure ratio signal transmitted from air fuel ratio (A/F)
sensor 1. This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio as close to
the theoretical mixture ratio as possible. However, the bas ic mixture ratio is not necessarily controlled as orig-
inally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and characteristic
changes during 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 air fuel ratio (A/F) sensor 1 i ndicates whether the mixture ratio is RICH or LEAN com-
pared to the theoretical value. The signal then triggers a r eduction 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 long-term to compensate for continual deviation
of the short term fuel trim from t he central value. Such deviation will occur due to individual engine differences,
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 cycl e 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 four cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The four fuel injectors will then receive the signals two times for each engine cycle. SEF337W

Page 1877 of 4331

NISSAN LATIO 2009 Service Repair Manual EC
NP
O
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 e

EC
NP
O
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.
Electronic Ignition (EI) System INFOID:0000000004537021
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 - 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
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) INFOID:0000000004537022
INPUT/OUTPUT SIGNAL CHART 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
Battery Battery voltage*2
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
ABS actuator and electric unit (control unit) Vehicle speed*1
Combination meter Sensor Input Signal to ECM ECM function Actuator
Park/neutral position (PNP) switch Neutral position
Fuel cut control Fuel 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
ABS actuator and electric unit (control unit) Vehicle speed*
Combination meter

Page 1878 of 4331

NISSAN LATIO 2009 Service Repair Manual Multiport Fuel Injection (MFI) Sys-
tem " .

Page 1879 of 4331

NISSAN LATIO 2009 Service Repair Manual EC
NP
O
AIR CONDITIONING
CUT CONTROL
Input/Output Signal Chart INFOID:0000000004537023
*1: This signal is sent to the ECM through CAN communication line.
*2: ECM determines the start signal status by

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