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Nissan March K13. Manual - part 143

SYSTEM

EC-33

< SYSTEM DESCRIPTION >

[HR12DE (TYPE 1)]

MULTIPORT FUEL INJECTION SYSTEM : System Description

INFOID:0000000005995401

INPUT/OUTPUT SIGNAL CHART

*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.
*3: This signal is sent to the ECM through CAN communication line.

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 (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
• High-load, high-speed operation

• During deceleration
• During high engine speed operation

Sensor

Input signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)

Engine speed

Piston position

Fuel injection
& mixture ratio
control

Fuel 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

PNP signal

Battery

Battery voltage

Knock sensor

Engine knocking condition

Heated oxygen sensor 2*

Density of oxygen in exhaust gas

EPS control unit

EPS operation signal

Combination meter

Vehicle speed signal

BCM

A/C ON signal

Blower fan ON signal

EC-34

< SYSTEM DESCRIPTION >

[HR12DE (TYPE 1)]

SYSTEM

MIXTURE RATIO FEEDBACK CONTROL (CLOSED LOOP CONTROL)

The mixture ratio feedback system provides the best air-fuel mixture ratio for drivability and emission control.
The three way catalyst (manifold) can 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-25, "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 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 Air fuel ratio (A/F) sensor 1 or its circuit
- Insufficient activation of heated sensor 1 at low engine coolant temperature
- High engine coolant temperature
- During warm-up
- When starting the engine

MIXTURE RATIO SELF-LEARNING CONTROL

The mixture ratio feedback control system monitors the mixture 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 basic 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 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 Air fuel ratio (A/F) sensor 1 indicates whether the mixture ratio is RICH or LEAN com-
pared to the theoretical 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 differ-
ences, wear over time and changes in the usage environment.

PBIB2793E

SYSTEM

EC-35

< SYSTEM DESCRIPTION >

[HR12DE (TYPE 1)]

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 three cylinders twice each engine cycle. In other words, pulse signals
of the same width are simultaneously transmitted from the ECM.
The three 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.

ELECTRIC IGNITION SYSTEM

ELECTRIC IGNITION SYSTEM : System Diagram

INFOID:0000000005995402

ELECTRIC IGNITION SYSTEM : System Description

INFOID:0000000005995403

INPUT/OUTPUT SIGNAL CHART

JSBIA0318GB

JSBIA0319GB

EC-36

< SYSTEM DESCRIPTION >

[HR12DE (TYPE 1)]

SYSTEM

*1: ECM determines the start signal status by the signals of engine speed and battery voltage.
*2: This signal is sent to the ECM through CAN communication line.

SYSTEM DESCRIPTION

Firing order: 1 - 2 - 3
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 (PHASE) sig-
nal. Computing 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.

AIR CONDITIONING CUT CONTROL

Sensor

Input signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)

Engine speed

Piston position

Ignition timing
control

Ignition coil (with power tran-
sistor)

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

Park/neutral position (PNP) switch

PNP signal

Battery

Battery voltage

Knock sensor

Engine knocking

Combination meter

Vehicle speed signal

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