SsangYong Rexton. Service manual — part 428
SSANGYONG Y200
1F2-30 M161 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
“modes”.
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 the amount
FUEL SYSTEM
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 HO2S
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
1F2-32 M161 ENGINE CONTROLS
FUEL PUMP
YAD1F240
Requirements for Fuel Pump
Item
System Pressure
Maximum Pressure
Minimum Pressure
Nominal Voltage
Minimum Amount
of Fuel Supply
Specified Value
3.8 bar
8.5 bar (12 V)
5.0 bar (12 V)
12 V
114 Liter/ Hr
(12 V, 3.8 bar, -30 ~ +70° C)
Specified Value
30 Litre/ Hr
8 V
7.5 A
-30 ~ +70° C
165 Liter/ Hr
(12 V, 3.8 bar, -30 ~ +70° C)
Item
Minimum Delivery at 8V
Operating Voltage
Maximum Allowable
Current
Ambient Temperature
Maximum Amount of Fuel
Supply
1 Flange and Harness Assembly
2 Spring
3 Fuel Pump
4 Float
5 Thermistor
6 Float Arm
7 Thermistor Housing
8 Resistor Card and Wiper
M161 ENGINE CONTROLS 1F2-33
SSANGYONG Y200
YAD1F250
Circuit Description
When the ignition switch is turned ON, the ECM will activate the pump relay and run the in-tank fuel pump. The
fuel pump will operate as long as the engine is cranking or running and the ECM is receiving ignition reference
pulses.
If there are no reference pulses, the ECM will shut off the fuel pump within 2 seconds after the ignitions witch is
turned ON, engine stopped or engine stalled.
Fuel Pump Relay Inspection
Measure the voltage between the ECM terminal No. 33 and ground.
Failure
Code
Description
Trouble Area
Maintenance Hint
Fuel pump relay short
circuit to battery
Fuel pump relay short
circuit to ground or
open
When short circuit to power
source
When short circuit to ground
or open
•
Inspection the Engine Control Module
(ECM) pin 33 about short circuit or open
with bad contact
•
Inspection the fuel pump relay
•
Inspection the ECM
34
35
Ignition Switch : ON
Cranking
0 V (for 1 ~ 2 sec.)
0 V
SSANGYONG Y200
1F2-34 M161 ENGINE CONTROLS
Measure the Fuel Delivery from the Fuel Pump
1. Disconnect the return pipe from fuel distributor and insert the appropriate hose into it.
2. Place the hose end into the beaker with the minimum capacity of 1 Liter
3. Turn the ignition switch to “ON” position.
4. Connect the terminal No. 33 and No. 5 of ECM with a service wire.
5. Measure the fuel delivery from the fuel pump.
Measure the Current Consumption of Fuel Pump
1. Remove the fuel pump relay from fuse and relay box in trunk, and turn the ignition switch to “ON” position.
2. Using a multimeter, measure the current consumption by connecting the terminal No. 30 and No. 87 of the fuel
pump relay connector.
Specified Value
5 ~ 9 A
Notice: Replace the fuel pump relay if the measured value is over 9 A.
Specified Value
1 Liter/max. 35 sec.
Notice: Check the fuel filter and fuel line when the fuel delivery is not within specified value.
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