Infiniti F50. Manual - part 346

 

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Infiniti F50. Manual - part 346

 

 

ENGINE CONTROL SYSTEM

EC-25

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EC

System Chart

EBS00LVB

*1: This sensor is not used to control the engine system. This is used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This signal is sent to the ECM through CAN communication line.

Input (Sensor)

ECM Function

Output (Actuator)

Camshaft position sensor (PHASE)

Crankshaft position sensor (POS)

Mass air flow sensor

Engine coolant temperature sensor

Heated oxygen sensor 1

Throttle position sensor

Accelerator pedal position sensor

Park/neutral position (PNP) switch

Intake air temperature sensor

Power steering pressure sensor

Ignition switch

Battery voltage

Knock sensor

Refrigerant pressure sensor

Stop lamp switch

Fuel level sensor*

1

EVAP control system pressure sensor

Fuel tank temperature sensor*

1

Heated oxygen sensor 2*

2

TCM (Transmission control module)*

3

VDC/TCS/ABS control unit*

3

Air conditioner switch*

3

Wheel sensor*

3

Electrical load signal*

3

Fuel injection & mixture ratio control

Fuel injector

Electronic ignition system

Power transistor

Nissan torque demand control system

Electric throttle control actuator

Fuel injector

Fuel pump control

Fuel pump relay

Fuel pump control module
(FPCM)

On board diagnostic system

MIL (On the instrument panel)

Power valve control

VIAS control solenoid valve

Heated oxygen sensor 1 heater control

Heated oxygen sensor 1 heater

Heated oxygen sensor 2 heater control

Heated oxygen sensor 2 heater

EVAP canister purge flow control

EVAP canister purge volume control 
solenoid valve

Air conditioning cut control

Air conditioner relay

Cooling fan speed control

Cooling fan speed control solenoid 
valve

ON BOARD DIAGNOSIS for EVAP system

EVAP canister vent control valve

Vacuum cut valve bypass valve

EC-26

ENGINE CONTROL SYSTEM

Multiport Fuel Injection (MFI) System

EBS00LVC

INPUT/OUTPUT SIGNAL CHART

*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.

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.

<Fuel increase>

During warm-up

When starting the engine

During acceleration

Hot-engine operation

When selector lever 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
Piston position

Fuel injection 
& mixture ratio 
control

Fuel injectors

Camshaft position sensor (PHASE)

Mass air flow sensor

Amount of intake air

Engine coolant temperature sensor

Engine coolant temperature

Heated oxygen 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

Ignition switch

Start signal

Knock sensor

Engine knocking condition

Battery

Battery voltage

Power steering pressure sensor

Power steering operation

Heated oxygen sensor 2*

1

Density of oxygen in exhaust gas

VDC/TCS/ABS control unit*

2

VDC/TCS operation command

Air conditioner switch*

2

Air conditioner operation

Wheel sensor*

2

Vehicle speed

ENGINE CONTROL SYSTEM

EC-27

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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
heated oxygen 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
heated oxygen sensor 1, refer to 

EC-212

 . 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 heated oxygen 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 heated oxygen sensor 1 or its circuit

Insufficient activation of heated oxygen 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 heated oxygen
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 film) and characteristic changes
during 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 heated oxygen sensor 1 indicates whether the mixture ratio is RICH or LEAN compared
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 differences,
wear over time and changes in the usage environment.

PBIB0121E

EC-28

ENGINE CONTROL SYSTEM

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 eight cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The eight 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 or operation of the engine at excessively high speeds.

Electronic Ignition (EI) System

EBS00LVD

INPUT/OUTPUT SIGNAL CHART

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

SYSTEM DESCRIPTION

The ignition timing is controlled by the ECM to maintain the best air-
fuel ratio for every running condition of the engine. The ignition tim-
ing data is stored in the ECM. This data forms the map shown.
The ECM receives information such as the injection pulse width
crankshaft position sensor (POS) signal, and camshaft position sen-
sor (PHASE) signal. Computing this information, ignition signals are
transmitted to the power transistor.
e.g., N: 1,800 rpm, Tp: 1.50 msec

°

BTDC

During the following conditions, the ignition timing is revised by the
ECM according to the other data stored in the ECM.

At starting

PBIB0122E

Sensor

Input Signal to ECM

ECM function

Actuator

Crankshaft position sensor (POS)

Engine speed
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

Ignition switch

Start signal

Knock sensor

Engine knocking

Park/neutral position (PNP) switch

Gear position

Battery

Battery voltage

Wheel sensor*

1

Vehicle speed

SEF742M

 

 

 

 

 

 

 

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