Infiniti I30 (A33). Manual — part 178
System Chart
NHEC0013
Input (Sensor)
ECM Function
Output (Actuator)
I
Camshaft position sensor (PHASE)
I
Crankshaft position sensor (REF)
I
Mass air flow sensor
I
Engine coolant temperature sensor
I
Heated oxygen sensor 1 (front)
I
Ignition switch
I
Throttle position sensor
I
Closed throttle position switch*3
I
Park/neutral position (PNP) switch
I
Air conditioner switch
I
Knock sensor
I
Intake air temperature sensor
I
Absolute pressure sensor
I
EVAP control system pressure sensor*1
I
Battery voltage
I
Power steering oil pressure switch
I
Vehicle speed sensor
I
Fuel tank temperature sensor*1
I
Crankshaft position sensor (POS)
I
Heated oxygen sensor 2 (rear)*2
I
TCM (Transmission control module)
I
Refrigerant pressure sensor
I
ABS/TCS control unit
I
Electrical load
I
Fuel level sensor*1
Fuel injection & mixture ratio control
Injectors
Electronic ignition system
Power transistor
Idle air control system
IACV-AAC valve
Fuel pump control
Fuel pump relay
On board diagnostic system
MIL (On the instrument panel)
Swirl control valve control
Swirl control valve control solenoid
valve
Power valve control
VIAS control solenoid valve
Heated oxygen sensor 1 heater (front) con-
trol
Heated oxygen sensor 1 heater
(front)
Heated oxygen sensor 2 heater (rear) control
Heated oxygen sensor 2 heater
(rear)
EVAP canister purge flow control
EVAP canister purge volume con-
trol solenoid valve
Air conditioning cut control
Air conditioner relay
Cooling fan control
Cooling fan relays
ON BOARD DIAGNOSIS for EVAP system
I
EVAP canister vent control valve
I
Vacuum cut valve bypass valve
*1: These sensors are not used to control the engine system. They are used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This switch will operate in place of the throttle position sensor to control EVAP parts if the sensor malfunctions.
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ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Chart
EC-27
Multiport Fuel Injection (MFI) System
DESCRIPTION
NHEC0014
Input/Output Signal Chart
NHEC0014S01
Sensor
Input Signal to ECM
ECM func-
tion
Actuator
Crankshaft position sensor (POS)
Engine speed (POS signal)
Fuel injec-
tion & mix-
ture ratio
control
Injectors
Crankshaft position sensor (REF)
Engine speed (REF signal)
Camshaft position sensor (PHASE)
Piston position
Mass air flow sensor
Amount of intake air
Engine coolant temperature sensor
Engine coolant temperature
Heated oxygen sensor 1 (front)
Density of oxygen in exhaust gas
Throttle position sensor
Throttle position
Throttle valve idle position
Park/neutral position (PNP) switch
Gear position
Vehicle speed sensor
Vehicle speed
Ignition switch
Start signal
Air conditioner switch
Air conditioner operation
Knock sensor
Engine knocking condition
Battery
Battery voltage
Absolute pressure sensor
Ambient air barometric pressure
Power steering oil pressure switch
Power steering operation
Heated oxygen sensor 2 (rear)*
Density of oxygen in exhaust gas
ABS/TCS control unit
TCS operation command
*: Under normal conditions, this sensor is not for engine control operation.
Basic Multiport Fuel Injection System
NHEC0014S02
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 both the crankshaft position sensor and the mass air
flow sensor.
Various Fuel Injection Increase/Decrease Compensation
NHEC0014S03
In addition, the amount of fuel injected is compensated to improve engine performance under various oper-
ating conditions as listed below.
<Fuel increase>
I
During warm-up
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When starting the engine
I
During acceleration
I
Hot-engine operation
I
When selector lever is changed from “N” to “D”
I
High-load, high-speed operation
<Fuel decrease>
I
During deceleration
I
During high engine speed operation
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System
EC-28
Mixture Ratio Feedback Control (Closed loop control)
NHEC0014S04
SEF336WA
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission con-
trol. The three way catalyst (Manifold) can then better reduce CO, HC and NOx emissions. This system uses
a heated oxygen sensor 1 (front) in the exhaust manifold to monitor if the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about the
heated oxygen sensor 1 (front), refer to EC-192. This maintains the mixture ratio within the range of stoichio-
metric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 (rear) is located downstream of the three way catalyst (Manifold). Even if the switch-
ing characteristics of the heated oxygen sensor 1 (front) shift, the air-fuel ratio is controlled to stoichiometric
by the signal from the heated oxygen sensor 2 (rear).
Open Loop Control
NHEC0014S05
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.
I
Deceleration and acceleration
I
High-load, high-speed operation
I
Malfunction of heated oxygen sensor 1 (front) or its circuit
I
Insufficient activation of heated oxygen sensor 1 (front) at low engine coolant temperature
I
High engine coolant temperature
I
During warm-up
I
After shifting from “N” to “D”
I
When starting the engine
Mixture Ratio Self-learning Control
NHEC0014S06
The mixture ratio feedback control system monitors the mixture ratio signal transmitted from the heated oxy-
gen sensor 1 (front). 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 con-
trolled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and char-
acteristic 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 the heated oxygen sensor 1 (front) 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.
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ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System (Cont’d)
EC-29
Fuel Injection Timing
NHEC0014S07
SEF179U
Two types of systems are used.
Sequential Multiport Fuel Injection System
NHEC0014S0701
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
NHEC0014S0702
Fuel is injected simultaneously into all six cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The six 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
NHEC0014S08
Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
Electronic Ignition (EI) System
DESCRIPTION
NHEC0015
Input/Output Signal Chart
NHEC0015S01
Sensor
Input Signal to ECM
ECM func-
tion
Actuator
Crankshaft position sensor (POS)
Engine speed (POS signal)
Ignition
timing con-
trol
Power transistor
Crankshaft position sensor (REF)
Engine speed (REF signal)
Camshaft position sensor (PHASE)
Piston position
Mass air flow sensor
Amount of intake air
Engine coolant temperature sensor
Engine coolant temperature
Throttle position sensor
Throttle position
Throttle valve idle position
Vehicle speed sensor
Vehicle speed
Ignition switch
Start signal
Knock sensor
Engine knocking
Park/neutral position (PNP) switch
Gear position
Battery
Battery voltage
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System (Cont’d)
EC-30
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