Infiniti M45 (Y34). Manual — part 334
ENGINE CONTROL SYSTEM
EC-25
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EC
System Chart
ABS002D3
*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)
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Crankshaft position sensor (POS)
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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
Intake valve timing control
Intake valve timing control solenoid
valve
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
ABS002D4
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 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
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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 injector
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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EC
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
. 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
ABS002D5
INPUT/OUTPUT SIGNAL CHART
*: 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
A
°
BTDC
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
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*
Vehicle speed
SEF742M
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