Fuel System - SSANGYONG Rexton Y200 Manual

1F1-30 M162 ENGINE CONTROLS
The function of the fuel metering system is to deliver
the correct amount of fuel to the engine under all
operating conditions.
The fuel is delivered to the engine by the individual
fuel injectors mounted into the intake manifold near
each cylinder.
The main fuel control sensors are the Mass Air Flow
(MAF) sensor and the oxygen (O2) sensors.
The MAF sensor monitors the mass flow of the air being
drawn into the engine. An electrically heated element
is mounted in the intake air stream, where it is cooled
by the flow of incoming air. Engine Control Module
(ECM) modulates the flow of heating current to maintain
the temperature differential between the heated film
and the intake air at a constant level. The amount of
heating current required to maintain the temperature
thus provides an index for the mass air flow. This
concept automatically compensates for variations in
air density, as this is one of the factors that determines
the amount of warmth that the surrounding air absorbs
from the heated element. MAF sensor is located
between the air filter and the throttle valve.
Under high fuel demands, the MAF sensor reads a
high mass flow condition, such as wide open throttle.
The ECM uses this information to enrich the mixture,
thus increasing the fuel injector on—time, to provide
the correct amount of fuel. When decelerating, the mass
flow decreases. This mass flow change is sensed by
the MAF sensor and read by the ECM, which then
decreases the fuel injector on—time due to the low fuel
demand conditions.
The O2 sensors are located in the exhaust pipe before
catalytic converter. The O2 sensors indicate to the ECM
the amount of oxygen in the exhaust gas, and the ECM
changes the air/fuel ratio to the engine by controlling
the fuel injectors. The best air/fuel ratio to minimize
exhaust emissions is 14.7 to 1, which allows the
catalytic converter to operate most efficiently. Because
of the constant measuring and adjusting of the air/fuel
ratio, the fuel injection system is called a "closed loop"
system.
The ECM uses voltage inputs from several sensors to
determine how much fuel to provide to the engine. The
fuel is delivered under one of several conditions, called
' ' m o d e s " .
Starting Mode
When the ignition is turned ON, the ECM turns the fuel
pump relay on for 1 second. The fuel pump then builds
fuel pressure. The ECM also checks the Engine Coolant
Temperature (ECT) sensor and the Throttle Position (TP)
sensor and determines the proper air/fuel ratio for
starting the engine. This ranges from1.5 to 1 at
-36 ° C (-33 ° F) coolant temperature to 14.7 to 1 at
94 ° C (201 ° F) coolant temperature. The ECM controls

FUEL SYSTEM

the amount of fuel delivered in the starting mode by
changing how long the fuel injector is turned on and
off. This is done by ''pulsing" the fuel injectors for
very short times.
Run Mode
The run mode has two conditions called ''open loop"
and ''closed loop".
Open Loop
When the engine is first started and it is above 690 rpm,
the system goes into "open loop" operation. In "open
loop", the ECM ignores the signal from the O2S and
calculates the air/fuel ratio based on inputs from the
ECT sensor and the MAF sensor. The ECM stays in
"open loop" until the following conditions are met:
•
The O2 has a varying voltage output, showing that
it is hot enough to operate properly.
•
The ECT sensor is above a specified temperature
(22.5 °C).
•
A specific amount of time has elapsed after starting
the engine.
Closed Loop
The specific values for the above conditions vary with
different engines and are stored in the Electronically
Erasable programmable Read-Only Memory (EEPROM).
When these conditions are met, the system goes into
"closed loop" operation. In "closed loop", the ECM
calculates the air/fuel ratio (fuel injector on-time) based
on the signals from the O2 sensors. This allows the
air/fuel ratio to stay very close to 14.7 to 1.
Acceleration Mode
The ECM responds to rapid changes in throttle position
and airflow and provides extra fuel.
Deceleration Mode
The ECM responds to changes in throttle position and
airflow and reduces the amount of fuel. When
deceleration is very fast, the ECM can cut off fuel
completely for short periods of time.
Battery Voltage Correction Mode
When battery voltage is low, the ECM can compensate
for a weak spark delivered by the ignition module by
using the following methods:
•
Increasing the fuel injector pulse width.
•
Increasing the idle speed rpm.
•
Increasing the ignition dwell time.
Fuel Cut-Off Mode
No fuel is delivered by the fuel injectors when the
ignition is off. This prevents dieseling or engine run-
on. Also, the fuel is not delivered if there are no reference
pulses received from the CKP sensor. This prevents
flooding.
SSANGYONG Y200