SsangYong Musso. Manual - part 106

1F-8 ENGINE CONTROLS

SSANGYONG  Y158

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 fur-
ther 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
1800rpm

Driving

When driving (part/full throttle), the servo motor controls
the throttle valve in line with the various load states and
according to the input signals from the pedal value sen-
sor according to the input signals from the pedal value
sensor according to the position of the accelerator ped-
al.

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;

•••••

Idle speed control

•••••

Cruise control

•••••

Reducing engine torque for ASR/ABS operation

•••••

Electronic accelerator emergency running

•••••

Storing faults

•••••

Data transfer through CAN

RESONANCE FLAP (3.2L DOHC)

A pneumatically actuated resonance flap is located on
the intake manifold. This effect is a kind of variable in-
take system for turbo-charging in accordance with reso-
nance  oscillation. The will be controlled by ECM
according to the throttle angle (position) and engine
speed (rpm).

Resonance flap closed

 (at idle/partial load : less than about 3,800 rpm) The
switch valve will be adjusted by ECM and resonance
flap will be closed. By increasing air flow passage through
dividing intake air flow toward both air collection housing.
This leads to a significant increase in the torque in the
lower speed range.

Resonance flap open

 (at full load : over about 3,800 rpm)

This switch valve will be adjusted by ECM and reso-
nance flap will be opened. When this flap is open, the
collected air volume in resonance tube is not divided.

The cylinder on the intake stroke uses the air in both in-
take lines of the resonance intake manifold.

ACCELERATOR PEDAL POSITION
SENSOR

The Accelerator Pedal Position (APP) sensor consists
of two potentiometers and is connected to the accelera-
tor pedal. The APP sensor electrical circuit consists of
two 5-volt supply lines and two ground lines, both pro-
vided by the Engine Control Module (ECM). The ECM
calculates the accelerator pedal position by monitoring
the voltages on these signal lines. The APP sensor out-
put changes as the accelerator pedal is moved.

The outputs of the APP sensor 1 and sensor 2 are low,
about 0.5 volt and 0.3 volt respectively at the closed
throttle position. As pushing the accelerator pedal, the
output increases so that the output voltages will be about
4.5 volts and 2.3 volts individually when accelerating  fully
with the kickdown, at Wide Open Throttle (WOT).

The ECM can determine fuel delivery based on APP sig-
nal (driver demand). A broken or loose APP sensor can
cause intermittent bursts of fuel from the injector and
an unstable idle, because the ECM thinks the throttle
is moving. A problem in any of the APP sensor circuits
should set a Diagnostic Trouble Codes (DTCs) P0220.
Once the DTC is set, the ECM will substitute a default
value for the APP sensor and some vehicle performance
will return.

CATALYST MONITOR OXYGEN
SENSORS

Three-way catalytic converters are used to control emis-
sions of  hydrocarbons (HC), carbon monoxide (CO), and
oxides of nitrogen (NOx). The catalyst within the
converters promotes a chemical reaction. This reaction
oxidizes the HC and CO present in the exhaust gas and
converts them into harmless water vapor and carbon
dioxide. The catalyst also reduces NOx by converting it
to nitrogen. The ECM can monitor this process using
the two heated O2 sensors (2.3L DOHC); O2 Bank 1
Sensor 1 and O2 Bank 1 Sensor 2 or four heated O2
sensors (3.2L DOHC); O2 Bank 1 Sensor 1, O2 Bank 1
Sensor 2, O2 Bank 2 Sensor 3 and O2 Bank 2 Sensor
4. These sensors produce an output signal which
indicates the amount of oxygen present in the exhaust
gas entering and leaving the three-way converter.

This indicates the catalyst’s ability to efficiently convert
exhaust gasses. In example if the catalyst is operating
efficiently, the O2 Bank 1 Sensor 1 sensor signals will
be  more active than the signals produced by the O2
Bank 1 Sensor 2 sensor. The O2 sensors’ main function
is cata-lyst monitoring, but they also have a limited role

ENGINE CONTROLS 1F-9

SSANGYONG  Y158

in fuel  control. If a sensor output indicates a voltage
either above or below the 450 mv bias voltage for an
extended  period of time, the Engine Control Module
(ECM) will  make a slight adjustment to fuel trim to
ensure that fuel delivery is correct for catalyst monitoring.

A problem with the O2 Sensor circuit will set several
DTCs as DTC P0131, P0132, P0133, P0134 or P0135
depending on the special condition.

A fault in the heating circuit of oxygen sensor will result
in lower oxygen sensor response. This may  cause
incorrect catalyst monitor diagnostic results.

INTAKE AIR TEMPERATURE
SENSOR

The Intake Air Temperature (IAT) sensor is a thermistor,
a resistor which changes value based on the temperature
of the air entering the engine. Low temperature produces
a high resistance (39.260 ohms at -40 °C [-40 °F]), while
high temperature causes a low resistance (130 ohms at
130 °C [266 °F]).

The Engine Control Module (ECM) provides 5 volts to
the IAT sensor through a resistor in the ECM and mea-
sures 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.

A failure in the IAT sensor circuit sets a diagnostic
trouble code P0111, P0112 or P0113.

HOT FILM MASS AIR FLOW
METER (3.2L DOHC)

The Hot Film Mass air flow meter (HFM) with recogni-
tion of  flow direction related to pulsating flow is designed
for recording load on ECM by measuring the output volt-
age proportional to the reference voltage of the ECM.

HFM is a thermal flow meter whose sensor element with
its temperature sensors and heating area is ex-posed
to the mass air flow to be measured. A heating  area
located in the center of a thin membrane is con-trolled
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
incoming 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.

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 main-
tain 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
Engine Control Module (ECM) uses this information to
enrich the mixture, thus increasing the fuel injector on-
time, to provide the correct amount of fuel. When de-
celerating,  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.

A failure in the MAF sensor circuit sets a diagnostic
trouble codes P0101, P0102 or P0103.

To facilitate the installation of the HFM in the intake
passage, lubricating agents may be used. However, when
lubricants 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.

The following tables show the relationship between MAF
and output voltage.

MANIFOLD ABSOLUTE PRESSURE
SENSOR (2.3L DOHC)

The Manifold Absolute Pressure (MAP) sensor measures
the changes in the intake manifold pressure which result
from engine load and speed changes and converts these
to a voltage output.

A closed throttle on engine coast down produces a
relatively low MAP output. MAP is the opposite of
vacuum. When manifold pressure is high, vacuum is low.
The MAP sensor is also used to measure barometric
pressure. This is performed as part of MAP sensor
calculations. With the ignition ON and the engine not

Air mass flow (kg/h)

Voltage  (V)

0

0.95 – 1.05

10

1.28

15

1.41

30

1.71

60

2.16

120

2.76

250

3.51

370

3.93

480

4.23

640

4.56

800

4.82

1F-10 ENGINE CONTROLS

SSANGYONG  Y158

running, the Engine Control Module (ECM) will read the
manifold pressure as barometric pressure and adjust
the air/fuel ratio accordingly. This compensation for
a l t i t u d e   a l l o w s   t h e   s y s t e m   t o   m a i n t a i n   d r i v i n g
performance while holding emissions low.

The barometric function will update periodically during
steady driving or under a wide open throttle condition.
In the case of a fault in the barometric portion of the
MAP sensor, the ECM will set to the default value.

A failure in the MAP sensor circuit sets a diagnostic
trouble codes P0105, P0107, P0108.

ENGINE CONTROL MODULE

The Engine Control Module (ECM), located inside the
right side kick panel, is the control center of the fuel in-
jection  system. It constantly looks at the information
from various sensors and controls the systems that af-
fect the vehicle’s performance.

Engine RPM and air mass are used to measure the air
intake quantity resulting in fuel injection metering.

The ECM also performs the diagnostic functions of the
system. It can recognize operational problems, alert the
driver through the Malfunction Indicator Lamp (MIL), and
store diagnostic trouble code(s) which identify the
problem areas to aid the technician in making repairs.

There are no serviceable parts in the ECM. The calibra-
tions are stored in the ECM in the Programmable Read
Only Memory (PROM).

The ECM supplies either 5 or 12 volts to power the sen-
sors or switches. This is done through resistances in
the ECM which are so high in value that a test light will
not  come ON when connected to the circuit. In some
cases, even an ordinary shop voltmeter will not give an
accurate reading because its resistance is too low. You
must  use a digital voltmeter with a 10 M ohm input
impedance to get accurate voltage readings. The ECM
controls output  circuits such as the ignition coils, the
fuel injectors, the fuel pump relay, the intake manifold
resonance flap (3.2L DOHC), the camshaft actuator, fuel
tank shut off solenoid, Malfunction Indicator lamp (MIL),
or the A/C clutch relay, etc., by controlling the ground
circuit through transistors or a device called a “quad-
driver”.

FUEL INJECTOR

The Multipoint Fuel Injection (MFI) assembly is a sole-
noid-operated device controlled by the Engine Control
Module (ECM) that meters pressurized fuel to an each
individual cylinder. The injector sprays the fuel, in pre-
cise quantities at a point in time determined by the ECM,
directly toward the cylinder intake valve. ECM energizes
the fuel injector solenoid to lift the needle valve and to
flow the fuel through the orifice. This injector’s discharge
orifice is calibrated to meet the effective fuel atomization
necessary for both ensuring the maximum homogeneity
in the air-fuel mixture and holding the condensation along

the walls of the intake tract to a minimum.

Fuel enters the top feed injector from above and flows
through its vertical axis. The lower end extends into the
intake valve. Fuel from the tip is directed at the intake
valve, causing it to become further atomized and vapor-
ized before entering the combustion chamber.

A fuel injector which is stuck partially open would cause
a loss of fuel pressure after the engine is shut down.

Also, an extended crank time would be noticed on some
engines. Dieseling could also occur because some fuel
could be delivered to the engine after the ignition is turned
off.

KNOCK SENSOR

The knock sensor detects abnormal knocking in the en-
gine. The two knock sensors are mounted in the engine
block near the cylinders. The sensors produce an output
voltage which increases with the severity of the knock.

This signal is sent to the Engine Control Module (ECM)
via a shielded cable. The ECM then adjusts the ignition
timing to reduce the spark knock.

STRATEGY-BASED DIAGNOSTICS

Strategy-Based Diagnostics

The strategy-based diagnostic is a uniform approach to
repair all Electrical/Electronic (E/E) systems. The diag-
nostic flow can always be used to resolve an E/E system
problem and is a starting point when repairs are neces-
sary.

The following steps will instruct the technician on how
to proceed with a diagnosis:

•••••

Verify the customer complaint. To verify the customer
complaint, the technician should know the normal
op-eration of the system.

•••••

Perform preliminary checks as follows:

•••••

Conduct a thorough visual inspection.

•••••

Review the service history.

•••••

Detect unusual sounds or odors.

•••••

Gather Diagnostic Trouble Code (DTC) information

to achieve an effective repair.

•••••

Check bulletins and other service information. This
includes videos, newsletters, etc.

•••••

Refer to service information (manual) system check(s).

•••••

Refer to service diagnostics.

No Trouble Found

This condition exists when the vehicle is found to oper-
ate normally. The condition described by the customer
may be normal. Verify the customer complaint against
another vehicle that is operating normally. The condition
may be intermittent. Verify the complaint under the con-
ditions described by the customer before releasing the
vehicle.

ENGINE CONTROLS 1F-11

SSANGYONG  Y158

Re-examine the complaint.

When the complaint cannot be successfully found or
isolated, a re-evaluation is necessary. The complaint
should be re-verified and could be intermittent as de-
fined in “Intermittents”, or could be normal.

After isolating the cause, the repairs should be made.
Validate for proper operation and verify that the symp-
tom has been corrected. This may involve road testing
or other methods to verify that the complaint has been
resolved under the following conditions:

•••••

Conditions noted by the customer.

•••••

If a DTC was diagnosed, verify a repair by duplicating
conditions present when the DTC was set as noted
in the Failure Records or Freeze Frame data.

Verifying Vehicle Repair

Verification of the vehicle repair will be more compre-
hensive  for vehicles with Euro On-Board Diagnostic
(EOBD)  system diagnostics. Following a repair, the
technician should perform the following steps:

Important: Follow the steps below when you verify re-
pairs on EOBD systems. Failure to follow these steps
could result in unnecessary repairs.

Review and record the Failure Records and the Freeze
Frame data for the DTC which has been diagnosed
(Freeze Fame data will only be stored for an A or B type
diagnostic and only if the Malfunction Indicator Lamp
has been requested).

•••••

Clear the DTC(s).

•••••

Operate the vehicle within conditions noted in the
Failure Records and Freeze Frame data.

•••••

Monitor the DTC status information for the specific
DTC which has been diagnosed until the diagnostic
test associated with that DTC runs.

EOBD SERVICEABILITY ISSUES

Based on the knowledge gained from Euro On-Board
Diagnostic (EOBD) experience in the 2001 model years,
this list of non-vehicle faults that could affect the
performance of the EOBD system has been compiled.

These non-vehicle faults vary from environmental condi-
tions to the quality of fuel used. With the introduction of
EOBD across the entire passenger car and light-duty
truck market in 2000, illumination of the Malfunction Indi-
cator Lamp (MIL) due to a non-vehicle fault could lead
to misdiagnosis of the vehicle, increased warranty ex-
pense and customer dissatisfaction. The following list
of non-vehicle faults does not include every possible fault
and may not apply equally to all product lines.

Fuel Quality

Fuel quality is not a new issue for the automotive indus-
try, but its potential for turning ON the MIL with EOBD
systems is new.

Fuel additives such as “dry gas” and “octane enhanc-
ers” may affect the performance of the fuel. If this results
in an incomplete combustion or a partial burn, it will set
Diagnostic Trouble Code (DTC) P0300. The Reid Vapor
Pressure of the fuel can also create problems in the fuel
system, especially during the spring and fall months
when severe ambient temperature swings occur. A high
Reid Vapor Pressure could show up as a Fuel Trim DTC
due to excessive canister loading. High vapor pressures
generated in the fuel tank can also affect the Evapora-
tive Emission diagnostic.

Using fuel with the wrong octane rating for your vehicle
may cause driveability problems. Many of the major fuel
companies advertise that using “premium” gasoline will
improve the performance of your vehicle. Most premium
fuels use alcohol to increase the octane rating of the
fuel. Although alcohol-enhanced fuels may raise the oc-
tane rating, the fuel’s ability to turn into vapor in cold
temperatures deteriorates. This may affect the starting
ability and cold driveability of the engine.

Low fuel levels can lead to fuel starvation, lean engine
operation, and eventually engine misfire.

Non-OEM Parts

The EOBD system has been calibrated to run with Origi-
nal Equipment Manufacturer (OEM) parts. Aftermarket
electronics, such as cellular phones, stereos, and anti-
theft devices, may radiate Electromagnetic Interference

 (EMI) into the control system if they are improperly
installed. This may cause a false sensor reading and
turn ON the MIL.

Environment

Temporary environmental conditions, such as localized
flooding, will have an effect on the vehicle ignition
system. If the ignition system is rain-soaked, it can
temporarily cause engine misfire and turn ON the MIL.

Vehicle Marshaling

The transportation of new vehicles from the assembly
plant to the dealership can involve as many as 60 key
cycles within 2 to 3 miles of driving. This type of opera-
tion  contributes to the fuel fouling of the spark plugs
and will turn ON the MIL with a set DTC P0300.

Poor Vehicle Maintenance

The sensitivity of the EOBD will cause the MIL to turn
ON if the vehicle is not maintained properly. Restricted
air filters, fuel filters, and crankcase deposits due to
lack of  oil changes or improper oil viscosity can trigger
actual vehicle faults that were not previously monitored
prior to EOBD. Poor vehicle maintenance can not be
classified as a “non-vehicle fault,” but with the sensitivity
of the EOBD, vehicle maintenance schedules must be
more closely followed.