SSANGYONG KORANDO 1997 Service Repair Manual

M161 ENGINE CONTROLS 1F2 -- 53
D AEW OO M Y_2000
Fuel Pressure Test
Tools Required
103 589 00 21 00 Fuel Pressure Gauge
1. Turn the ignition switch to “OFF” position.
2. Remove the fuel pressure test connector.
YAA1F700
3. Connect the fuel pressure gauge to the fuel pressure test connector.
4. Test the fuel pressure at idling by operating the engine using the fuel pressure gauge 103 589 00 21 00.
Vacuum Hose Connected (bar)
3.2~3.6
Vacuum Hose Disconnected (bar)3.7~4.2
5. Replace the pressure regulator diaphragm if out of the specification.
Internal Leakage Test
1. Connect the fuel pressure gauge 103 589 00 21 00 to
the fuel pressure test connector.
YAA1F0K0
2. Stop the engine for approximately 30 minutes and then check the fuel pressure changes.
Pressure change
Fuel pressure drops slowlyDFuel leakage at the injector
DFaulty fuel pressure regulator ’s diaphragm and O-ring
Fuel pressure drops rapidlyDFaulty check valve in the fuel pump
3. If there is no change in fuel pressure and maintain the following pressure over 30minutes, it is normal.
Fuel pressure (bar)
≥2.5

1F2 -- 54 M161 ENGINE CONTROLS
D AEW OO M Y_2000
FUEL PRESSURE REGULATOR
YA A 1 F0 F0
Function of the Fuel Pressure Regulator
The fuel pressure regulator maintains the fuel pressure
in the fuel line with the pressure of 3.2 bars to 3.8 bars
according to the intake manifold pressure. This operat-
ing pressure cannot be changed, and the fuel injection
volume will be only determined by the injection time.
Over supplied fuel returns to the fuel tank through the
return line.

There is no negative pressure applied to the spring
chamber (9) during the full load, and it is separated from
the fuel chamber (8) by the diaphragm (5).
When the fuel pressure goes up, the diaphragm forces
the compression spring (6) in the direction of compres-
sion . At this moment, the valve (3) sticks to the dia-
phragm by the fuel pressure, and the fuel return line (2)
opens. The fuel over supplied returns to the fuel tank
through the return line.
YAA1F490
2. Fuel return line
3. Valve
5. Diaphragm
6. Compression Spring
8. Fuel Chamber
9. Spring Chamber
A. Valves Closed
B. Valves Opened

M161 ENGINE CONTROLS 1F2 -- 55
D AEW OO M Y_2000
The pressure difference between the fuel pressure and
the intake manifold is about 3.8 bars during the full load.
YAA1F500
1. Fuel Pressure Regulator
2. Intake Manifold
3. Fuel Return (to fuel tank)
4. Fuel Supply (from fuel pump)
5. Fuel Pressure (approx. 3.8 bars)
6. Intake Manifold Negative Pressure (0 bar)

The spring chamber (9) is connected to the intake man-
ifold with the vacuum hose at the intake pipe connection
(7). The negative pressure generated in the intake man-
ifold activates the diaphragm, and thus the fuel pressure
gets reduced to the rate of the operating extent of the
diaphragm by the intake manifold’s negative pressure.
YAA1F510
Consequently, the fuel pressure in the fuel distributor
changes by the intake manifold’s negative pressure, and
the injector ’s fuel pressure gets reduced independentlyto the throttle valve’s position. Thus, the fuel injection
volume can only be determined according to the injec-
tor’s injecting duration.
The pressure difference between the fuel pressure and
the intake manifold is approx. 3.2 bars during idling.
YAA1F520
1. Fuel Pressure Regulator
2. Intake Manifold
3. Fuel Return (to fuel tank)
4. Fuel Supply (from fuel pump)
7. Fuel Pressure (approx. 3.2 bars)
8. Intake Manifold Negative Pressure (0.6 bars)

YAA1F530
A. Fuel pressure
B. Intake Manifold Negative Pressure
LL. Idling
TL. Partial load
VL. Full load

1F2 -- 56 M161 ENGINE CONTROLS
D AEW OO M Y_2000
INDUCTION SYSTEM
THROTTLE VALVE ACTUATOR
YAA1F540
The throttle actuator is actuated by the Engine Control Module (ECM) according to the position of the accelerator pedal
position.
It has two potentiometers which signal the position of the throttle valve to the ECM to enable it to recognize the various
engine load states.
Ignition “Off”
In the de-- energized states the throttle valve position is determined to be spring capsule.
Ignition “On”
When the ignition S/W on the servo motor in the throttle actuator is operated by the ECM. The throttle valve adopts a
position in line with the coolant temperature.
Closed position
In the closed throttle position, the servo motor controls engine speed by operating the throttle valve further (greater
mixture) or closing it further (reduced mixture), depending on coolant temperature and engine load. When this is done,
the throttle valve can be closed further by the servo motor overcoming the force of the spring capsule (mechanical end
stop). If the actuator is de-- energized, the throttle valve is resting against the spring capsule.
Consequently, the throttle valve opening is a constant 10-- 12°approximately.
At no load, this produces an engine speed of about 1,800 rpm
Driving
When driving (part/full throttle), the servo motor controls the throttle valve in line with the various load states and ac-
cording to the input signals from the pedal value sensor according to the input signals from the pedal value sensor
according to the position of the accelerator pedal.
The function of the EA (electronic accelerator) in the ECM determines the opening angle of the throttle valve through
the throttle actuator. Further functions are;
DIdle speed control
DCruise control
DReducing engine torque for ASR/ABS operation
DElectronic accelerator emergency running
DStoring faults
DData transfer through CAN

M161 ENGINE CONTROLS 1F2 -- 57
D AEW OO M Y_2000
KAB1F240
Failure
CodeDescriptionTrouble AreaMaintenance Hint
104Throttle position sensor
1 low voltageTPS 1 short circuit to ground
or open
105Throttle position sensor
1 high voltageTPS 1 short circuit to power
108Throttle position sensor
2 low voltageTPS 2 short circuit to ground
or open
109Throttle position sensor
2 high voltageTPS 2 short circuit to powerDMonitoring the actual values through
scantool
116Throttle actuator
learning control failureWhen actuator adaption
fluctuation or not meet the
conditionscantool
DInspection the ECM pin 84, 85, 87,
112, 67, 68 about short circuit or open
with bad contact
119Throttle valve return
spring failureWhen return spring defective
of actuator
withbadcontact
DInspection the throttle valve actuator
DInspection the ECM
121Throttle actuator failureWhen supply voltage of the
actuator short circuit to power
InspectiontheECM
123
Different mass air flow
sensor signal with
throttle position sensorWhen shut down of output
driver
125Both throttle position
sensor failureWhen defective of both
potentiometers

1F2 -- 58 M161 ENGINE CONTROLS
D AEW OO M Y_2000
Failure
CodeDescriptionTrouble AreaMaintenance Hint
126
Throttle position sensor
1 not plausible with
Throttle position sensor
2
When difference between
TPS 1 and TPS 2DMonitoring the actual values through
scan tool
DIns
pection the ECMpin 84, 85, 87,
127High permanent throttle
signalWhen failure of wiring
harness or actuator
DInspectiontheECMpin84,85,87,
112, 67, 68 about short circuit or open
with bad contact
Itiththttlltt
185
Mass air flow sensor
and throttle position
sensor failureWhen difference between
MAF and TPS signal
DInspection the throttle valve actuator
DInspection the ECM
Circuit Description
The ECM supplies a 5 volt reference signal and a ground to the TP sensor. The TP sensor sends a voltage signal back
to the ECM relative to the throttle plate opening. The voltage signalwill vary from approximately 0.3 ~ 0.9 volts at
closed throttle, to over 4.0 ~ 4.6 volts at Wide Open Throttle (WOT).
The TP sensors serve for engine load control according to the drive pedal command. Load adjustments independent of
the drive pedal command can be implemented; such functions are, for instance, idle control, speed control, drive slip
control, load shock damping, and similar functions.
When the actuator current fails, the throttle valve is returned to emergency operating position by a spring. The throttle
valve position, thereby the actuator drive position checkback is provided by two potentiometers. The motor positions
the throttle valve against the return spring force. Motor and return spring are two separate energy sources. Each of
them is able to position the throttle valve in emergency position alone. Throttle valve position checkback and monitor-
ing is provided by two actual value potentiometers connected to the engine control electronics.
Throttle Actuator Inspection
1. Turn the ignition switch to “ON” position.
2. Measure the TPS 1 signal voltage at the ECM pin No. 87 and TPS 2 signal voltage at the ECM pin No. 85.
Pedal PositionSpecified Value
TPS1Closed0.3 ~ 0.9 vTPS1Opened4.0 ~ 4.6 v
TPS2Closed4.0 ~ 4.6 vTPS2Opened0.3 ~ 0.9 v
Throttle Actuator DC Motor Inspection
1. Turn the ignition switch to “ON” position.
2. Measure the signal voltage between the ECM pin No. 67 and No. 68.
Application
Specified Value
Ignition “ON”0.8 ~ 2.3 v
Engine StatusIdling1.0 ~ 2.5 v
(Coolant temperature is over 70°C)
Throttle Actuator DC Motor Resistance
1. Turn the ignition switch to “OFF” position.
2. Measure the resistance between the ECM pin No. 67 and No. 68.
Specified Value
<10Ω

M161 ENGINE CONTROLS 1F2 -- 59
D AEW OO M Y_2000
BLANK

1F2 -- 60 M161 ENGINE CONTROLS
D AEW OO M Y_2000
HOT FILM AIR MASS (HFM) SENSOR
YAA1F570
The Hot Film Air Mass (HFM) sensor with recognition of flow direction related to pulsating flow is designed for record-
ing load on Engine Control Module (ECM) by measuring the output voltage proportional to the reference voltage of the
ECM.
Mass Air Flow Sensor
Mass Air Flow (MAF) is a thermal flow meter whose sensor element with its temperature sensors and heating area is
exposed to the MAF to be measured. A heating area located in the center of a thin membrane is controlled to an over --
temperature by a heating resistor and a temperature sensor of this membrane. And the value of over -- temperature
depends on the temperature of the in-- flowing air.
Two temperature sensors on upstream and downstream of the heating area show the same temperature without in-
coming flow. With incoming flow, upstream part is cooled down but downstream temperature retains its temperature
more or less due to the air heated up in the heating area. This temperature difference in quantity and direction depends
on the direction of the incoming flow.
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 MAF. 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 (WOT). 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.
To facilitate the installation of the HFM in the intake passage, lubricating agents may be used. However, when lubri-
cants are used care must be taken to ensure that they do not enter the flow passage and cannot be sucked in with the
air flow.

M161 ENGINE CONTROLS 1F2 -- 61
D AEW OO M Y_2000
The following tables show the relationship between MAF and output voltage.
Mass Air Flow (kg/h)
Voltage (v)Mass Air Flow (kg/h)Voltage (v)
00.95 ~ 1.052503.51
101.283703.93
151.414804.23
301.716404.56
602.168004.82
1202.76
Intake Air Temperature
The Intake Air Temperature (IAT) sensor is a part of Hot Film Air Mass (HFM) sensor and is a thermistor, a resistor
which changes value based on the temperature of the air entering the engine. Low temperature produces a high resist-
ance, while high temperature causes a low resistance as the following table.
The ECM provides 5 volts to the IAT sensor through a resistor in the ECM and measures the change in voltage to
determine the IAT. The voltage will be high when the manifold air is cold and low when the air is hot. The ECM knows
the intake IAT by measuring the voltage.
The IAT sensor is also used to control spark timing when the manifold air is cold.
Te m p. (°C)
Rmin.(Ω)R nom. (Ω)R max. (Ω)
-- 4 0351403926043760
-- 2 0126601385015120
0511954995829
20229024202551
40109611661238
60565609654
80312340370
100184202222
120114127141
13091102114

1F2 -- 62 M161 ENGINE CONTROLS
D AEW OO M Y_2000
KAB1F250
Failure
CodeDescriptionTrouble AreaMaintenance Hint
03Intake air temperature
sensor low voltageIAT sensor short circuit to
ground or openDMonitoring the actual air temperature
throu
gh scan tool
04Intake air temperature
sensor high voltageIAT sensor short circuit to
power
throughscantool
DInspection the ECM pin 80, 79 about
short circuit or open with bad contact
05Intake air temperature
sensor plausibilityMalfunction in recognition of
IAT
When functional problem
p
DInspection the IAT sensor (integrated
in HFM sensor)
DInspection the ECM
09Mass air flow sensor
plausibilityMalfunction in recognition of
MAF
When air mass not plausibleDMonitoring the actual air mass flow
through scan tool
DIns
pection the ECMpin 81, 105 about
10Mass air flow sensor low
voltageMAF sensor short circuit to
ground or open
DInspectiontheECMpin81,105about
short circuit or open with bad contact
DInspection the MAF sensor (integrated
iHFM)
11Mass air flow sensor
high voltageMAF sensor short circuit to
powerin HFM sensor)
DInspection the ECM
Circuit Description
The heated element on the MAF is a platinum film resistor (heater). It is located on a ceramic plate together with the
other elements in the bridge circuit. The temperature sensitive resistor (flow sensor) also included in the bridge. The
separation of heater and flow sensor facilitates design of the control circuitry. Saw cuts are employed to ensure thermal
decoupling between the heating element and the intake air temperature (IAT) sensor. The complete control circuitry is
located on a single layer. The voltage at the heater provides the index for the mass air flow. The MAF’s electronic
circuitry then converts the voltage to a level suitable for processing in the ECM. This device does not need a burn off
process to maintain its measuring precision over an extended period. In recognition of the fact that most deposits
collect on the sensor element’s leading edge, the essential thermal transfer elements are located downstream on the
ceramic layer. The sensor element is also design to ensure that depositswill not influence the flow pattern around the
sensor.
The IAT sensor uses a thermistor to control the signal voltage to the ECM. The ECM supplies 5 volt reference and a
ground to the sensor. When the air is cold, the resistance is high; therefore the IAT signal voltagewill be high. If the
intake air is warm, resistance is low; therefore the IAT signal voltagewill be low.