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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
I 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
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