SsangYong Musso. Manual - part 108

1F-16 ENGINE CONTROLS

SSANGYONG  Y158

items:

•••••

Contaminated fuel.

•••••

Low fuel.

•••••

Fuel-fouled spark plugs.

•••••

Basic engine fault.

Fuel Trim System Monitor Diagnostic Operation

This system monitors the averages of short-term and
long-term fuel trim values. If these fuel trim values stay
at their limits for a calibrated period of time, a malfunc-
tion is  indicated. The fuel trim diagnostic compares the
averages of short-term fuel trim values and longterm fuel
trim values to rich and lean thresholds. If either value is
within the thresholds, a pass is recorded. If both values
are outside their thresholds, a rich or lean DTC will be
recorded.

The fuel trim system diagnostic also conducts an intru-
sive test. This test determines if a rich condition is being
caused by excessive fuel vapor from the Evaporative
Emission (EVAP) canister. In order to meet EOBD
requirements, the control module uses weighted fuel trim
cells to determine the need to set a fuel trim DTC. A
fuel trim DTC can only be set if fuel trim counts in the
weighted fuel trim cells exceed specifications. This

means that the vehicle could have a fuel trim problem
which is causing a problem under certain conditions (i.e.,
engine idle high due to a small vacuum leak or rough
idle due to a large vacuum leak) while it operates fine at
other times. No fuel trim DTC would set (although an
engine idle speed DTC or O2S DTC may set). Use a
scan tool to observe fuel trim counts while the problem
is occurring.

A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a
fuel trim fault.

Fuel Trim Cell Diagnostic Weights

No fuel trim DTC will set regardless of the fuel trim counts
in cell 0 unless the fuel trim counts in the weighted cells
are also outside specifications. This  means that the
vehicle could have a fuel trim problem which is causing
a problem under certain conditions (i.e. engine idle high
due to a small vacuum leak or rough  due to a large
vacuum leak) while it operates fine at other times. No
fuel trim DTC would set (although an engine idle speed
DTC or O2S DTC may set). Use a scan tool to observe
fuel trim counts while the problem is occurring.

ENGINE CONTROLS 1F-17

SSANGYONG  Y158

KAA1F0UA

SYSTEM DIAGNOSIS

DIAGNOSTIC AIDS

If an intermittent problem is evident, follow the guide-
lines below.

Preliminary Checks

Before using this section you should have already per-
formed the "Euro On-Board Diagnostic System Check.”

Perform a thorough visual inspection. This inspection
can often lead to correcting a problem without further
checks and can save valuable time. Inspect for the fol-
lowing conditions:

•••••

Engine Control Module (ECM) grounds for being
clean, tight, and in their proper location.

•••••

Vacuum hoses for splits, kinks, collapsing and proper
connections as shown on the Vehicle Emission Con-
trol Information label. Inspect thoroughly for any type
of leak or restriction.

•••••

Air leaks at the throttle body mounting area and the
intake manifold sealing surfaces.

•••••

Ignition wires for cracks, hardness, proper routing,
and carbon tracking.

•••••

Wiring for proper connections.

•••••

Wiring for pinches or cuts.

Diagnostic Trouble Code Tables

Do not use the Diagnostic Trouble Code (DTC) tables to
try and correct an intermittent fault. The fault must be

present to locate the problem.

Incorrect use of the DTC tables may result in the unnec-
essary replacement of parts.

Faulty Electrical Connections or Wiring

Most intermittent problems are caused by faulty electri-
cal connections or wiring. Perform a careful inspection
of suspect circuits for the following:

•••••

Poor mating of the connector halves.

•••••

Terminals not fully seated in the connector body.

•••••

Improperly formed or damaged terminals. All connec-
tor terminals in a problem circuit should be carefully
inspected, reformed, or replaced to insure contact
tension.

•••••

Poor terminal-to-wire connection. This requires re-
moving the terminal from the connector body.

Road Test

If a visual inspection does not find the cause of the prob-
lem, the vehicle can be driven with a voltmeter or a scan
tool connected to a suspected circuit. An abnormal

DIAGNOSTIC INFORMATION AND PROCEDURE

voltage or scan tool reading will indicate that the problem
is in that circuit.

If there are no wiring or connector problems found and a
DTC was stored, refer to the applicable DTC tables.

Intermittent Malfunction Indicator Lamp (MIL)

An intermittent Malfunction Indicator Lamp (MIL) with
no DTC present may be caused by the following:

•••••

Improper installation of electrical options such as
lights, two way radios, sound, or security systems.

•••••

MIL driver wire intermittently shorted to ground.

Fuel System

Some intermittent driveability problems can be attrib-
uted to  poor fuel quality. If a vehicle is occasionally run-
ning rough, stalling, or otherwise performing badly, ask
the customer about the following fuel buying habits:

•••••

Do they always buy from the same source? If so,
fuel quality problems can usually be discounted.

•••••

Do they buy their fuel from whichever fuel station that
is advertising the lowest price? If so, check the fuel
tank for signs of debris, water, or other contamina-
tion.

KAA1F0UA

YAB1F050

1F-18 ENGINE CONTROLS

SSANGYONG  Y158

Process of Flywheel Backlash
Compensation for Misfire Detection

When an ECM is reflashed, initialized or replaced, and
driveplate of flywheel has been replaced, follow these
procedures to relearn the Crankshaft Position (CKP)
system variation:

Caution: To avoid personal injury when performing
the flywheel adaptation procedure, always set the
vehicle parking brake and block the drive wheels.
Release the throttle immediately when the engine
starts to decelerate. Once the learning procedure is
completed, engine control will be learned to the
operator, and the engine will respond to the throttle
position.

STEP 1 : Initialization ECM to delete all adaptation val-

ues.

STEP 2 : Build-up following adaptation values.

•••••

Oxygen sensor adaptation values.

•••••

Idle controller adaptation values.

STEP 3 : Acceleation the vehicle in gear position 3 up

to 5500 rpm.

Caution : During this time, do not acceleration or
Brake.

STEP 5 : Check the compensation status through scan

tool.

STEP 6 : Fulfill this procedure again if not this value is

"0".

Parameter

Unit

Learning

Value

Disable Condition for Flywheel
Adaptation

1=YES / 0=NO

Engine speed is too high or to low

Symptom 17, 18, 20

 (engine speed fault)

Compensation process is in

preparation

Engine speed of gradient is too high,

or Brake is in use

No Decel. Fuel Shut Off, No Fuel Cut

0

1

2

3

4

5

ENGINE CONTROLS 1F-19

SSANGYONG  Y158

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