102
［
2
］
. Operation principle:
Single Port Injection System is applied on the vehicle equipped with 3 way catalyst converter .the system
insures air/fuel mixture ratio in the vicinity of the ideal air/fuel ratio.
The ideal air/fuel ratio is important for catalyst converter to work normally. The aim having the catalyst
converter installed is to reduce harmful exhaust emission. The
λ
sensor, analyzing oxygen content in
exhaust gas continuously , may ensure getting ideal mixture . If air/fuel ration is not ideal, ECU may adjust
the mixture consistence continuously by measuring fuel intake in progression.
Fuel system(fuel pump, fuel filter, pressure regulator) offers the fuel of 1 bar to fuel injector.
The fuel Injection value is proportional to the air sucked into the engine. Also the fuel is injected into
intake manifold synchronously with TDC. Under some specified condition, the amount of fuel needed for
engine circulation is too small to measure, the system may perform a asynchronous injection (inject once
instead of the normal injection ever several TDCs).
Ignition controller with inductive discharging is of electrostatic discharge type (distributorless). Ignition
advance is calculated by a basic chart (pressure, revolution) and trimmed by engine load, water temperature,
and air temperature. In addition, it may perform dynamic ignition advance to stabilize idle speed. Engine
idle speed actuator adjusts the by-pass pipe opening to keep idle value constant. And engine idle actuator is
consisted of linear stepper motor.
Generally, ECU receives input signal and operates output actuating device to integrate idle speed, spray,
ignition’s control. Moreover, HCMOS microprocessor, with wonderful static-prevention and high-speed
calculation ability and low power consumption, may fulfill the following functions:
·
The diagnosis for
resuming system operation. As a sensor fails, the diagnosis system may resumes the operation using the
stored value preset.
·
diagnosis for faulty Actuator condition
·
Even if stopped, as a system part fails , the
warning indicator will be energized and the information of fail type will be stored.
·
during service,
diagnostic tester may be connected and actuator may be operated to check for failure. 1.“I.A.W
6F
……
”ECU
Read the square figure (figure 160), ECU processes all sensor signals related with running parameters:
·
Intake manifold absolute pressure
·
The TDC and revolution of cylinder 1,4 and 2,3
·
Throttle valve
open position
·
Intake air temperature
·
Engine coolant temperature
·
A/C compressor switch
signal
·
Oxygen (
λ
) sensor signal (millivolt signal ) By this way, calculate air charge (process absolute
pressure, air temperature, speed, and throttle valve position signal) and use output circuit to control the
following:
·
control fuel injector switch on time for calculating fuel feed.
·
control by-pass air volume and
ignition advance for stepper motor compensating to control idle speed.
·
control two high pressure ignition
coil, and ignition energy of cylinder 1,4 and 2,3.
·
control fuel vapor recirculation solenoid switch on/off
also ECU features a complete self diagnostic for input sensor and output actuator. The diagnosis may be
performed by connecting CHE CK—UP1 with system and the failures detected will be shown on the
screen. For instance:
·
all sensor are shorted or opened, including pressure, air, water, throttle valve,
λ
sensor, TDC/RPM sensor ( signal sequence is missing).
·
Engine idle speed actuator (stepper motor)
doesn’t work.
·
stepper motor, fuel injector, and fuel pump circuits are shorted
·
high pressure ignition coil,
fuel vapor recirculation solenoid is shorted or opened.
Main parameters are shown according to the requirements: speed, water temperature, injection time,
ignition advance, intake manifold pressure, throttle valve position, battery voltage, stepper motor position
(steps).
When engine is stopped and ignition switch is on, ECU may perform active diagnostic function, which
