Opel Frontera UE. Manual - part 1561

 

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Opel Frontera UE. Manual - part 1561

 

 

6E–459

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Run Mode

The run mode has the following two conditions:

D

Open loop

D

Closed loop

When the engine is first started the system is in “open
loop” operation.  In “open loop,” the PCM ignores the
signal from the heated oxygen sensor (HO2S).  It
calculates the air/fuel ratio based on inputs from the TP,
ECT, and MAF sensors.
The system remains in “open loop” until the following
conditions are met:

D

The HO2S has a varying voltage output showing that
it is hot enough to operate properly (this depends on
temperature).

D

The ECT has reached a specified temperature.

D

A specific amount of time has elapsed since starting
the engine.

D

Engine speed has been greater than a specified RPM
since start-up.

The specific values for the above conditions vary with
different engines and are stored in the programmable
read only memory (PROM).  When these conditions are
met, the system enters “closed loop” operation.  In
“closed loop,” the PCM calculates the air/fuel ratio
(injector on-time) based on the signal from the HO2S.
This allows the air/fuel ratio to stay very close to 14.7:1.

Starting Mode

When the ignition is first turned “ON,” the PCM energizes
the fuel pump relay for two seconds to allow the fuel pump
to build up pressure.  The PCM then checks the engine
coolant temperature (ECT) sensor and the throttle
position (TP) sensor to determine the proper air/fuel ratio
for starting.
The PCM controls the amount of fuel delivered in the
starting mode by adjusting how long the fuel injectors are
energized by pulsing the injectors for very short times.

Throttle Body Unit

The throttle body has a throttle plate to control the amount
of air delivered to the engine.  The TP sensor are also
mounted on the throttle body.  Vacuum ports located
behind the throttle plate provide the vacuum signals
needed by various components.
Engine coolant is directed through a coolant cavity in the
throttle body to warm the throttle valve and to prevent
icing.

025RY00005

General Description (Electronic
Ignition System)

Crankshaft Position (CKP) Sensor

The crankshaft position (CKP) sensor provides a signal
used by the powertrain control module (PCM) to calculate
the ignition sequence.  The sensor initiates the 58X
reference pulses which the PCM uses to calculate RPM
and crankshaft position.  Refer to 

Electronic Ignition

System section for additional information.

Electronic Ignition

The electronic ignition system controls fuel combustion
by providing a spark to ignite the compressed air/fuel
mixture at the correct time.  To provide optimum engine
performance, fuel economy, and control of exhaust
emissions, the PCM controls the spark advance of the
ignition system.  Electronic ignition has the following
advantages over a mechanical distributor system:

D

No moving parts.

D

Less maintenance.

D

Remote mounting capability.

D

No mechanical load on the engine.

D

More coil cooldown time between firing events.

D

Elimination of mechanical timing adjustments.

D

Increased available ignition coil saturation time.

SECTION

6E–460

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

0013

Ignition Coils

A separate coil-at-plug module is located at each spark
plug.  The coil-at-plug module is attached to the engine
with two screws.  It is installed directly to the spark plug by
an electrical contact inside a rubber boot.  A three-way
connector provides 12-volt primary supply from the
15-amp ignition fuse, a ground-switching trigger line from
the PCM, and a ground.

060RY00022

Ignition Control

The ignition control (IC) spark timing is the PCM’s method
of controlling the spark advance and the ignition dwell.
The IC spark advance and the ignition dwell are
calculated by the PCM using the following inputs:

D

Engine speed.

D

Crankshaft position (58X reference).

D

Engine coolant temperature (ECT) sensor.

D

Throttle position (TP) sensor.

D

ION sensing module.

D

Park/Neutral position (PRNDL input).

D

Vehicle speed (vehicle speed sensor).

D

PCM and ignition system supply voltage.

D

The crankshaft position (CKP) sensor sends the PCM
a 58X signal related to the exact position of the
crankshaft.

TS22909

Based on these sensor signals and engine load
information,  the PCM sends 5V to each ignition coil.

060RY00116

This module has the function to energize and de-energize
the primary ignition coil in response to signals from the
PCM. The Throttle PCM controls ignition timing and dwell
time.
Continuity and out-or-range value check:
This diagnosis detects open circuit or short-circuiting in
the Electronic Spark Timing (EST) line by monitoring EST
signals. A failure determination is made when the signal
voltage remains higher or lower than the threshold for
corresponding fault code beyond a predetermined time
period.
Diagnosis enabling conditions are as follows:

D

RPM is higher than the specified threshold.

D

EST line is enabled.

SECTION

6E–461

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

060RY00029

Ignition Control PCM Output

The PCM provides a zero volt (actually about 100 mV to
200 mV) or a 5-volt output signal to the ignition control (IC)
module.  Each spark plug has its own primary and
secondary ignition coil assembly (”coil-at-plug”) located
at the spark plug itself.  When the ignition coil receives the
5-volt signal from the PCM, it provides a ground path for
the B+ supply to the primary side of the coil-at -plug
module. When the PCM shuts off the 5-volt signal to the
ION sensing module, the ground path for the primary coil
is broken.  The magnetic field collapses and induces a
high voltage secondary impulse which fires the spark plug
and ignites the air/fuel mixture.
The circuit between the PCM and the ignition coil is
monitored for open circuits, shorts to voltage, and shorts
to ground.  If the PCM detects one of these events, it will
set one of the following DTCs:

D

P0351:  Ignition coil Fault on Cylinder #1

D

P0352:  Ignition coil Fault on Cylinder #2

D

P0353:  Ignition coil Fault on Cylinder #3

D

P0354:  Ignition coil Fault on Cylinder #4

D

P0355:  Ignition coil Fault on Cylinder #5

D

P0356:  Ignition coil Fault on Cylinder #6

Powertrain Control Module (PCM)

The PCM is responsible for maintaining proper spark and
fuel injection timing for all driving conditions.  To provide
optimum derivability and emissions, the PCM monitors
the input signals from the following components in order
to calculate spark timing:

D

Engine coolant temperature (ECT) sensor.

D

Intake air temperature (IAT) sensor.

D

Mass air flow (MAF) sensor.

D

PRNDL input from transmission range switch.

D

Throttle position (TP) sensor.

D

Vehicle speed sensor (VSS) .

D

Crankshaft position (CKP) sensor.

Spark Plug

Although worn or dirty spark plugs may give satisfactory
operation at idling speed, they frequency fail at higher
engine speeds.  Faulty spark plugs may cause poor fuel
economy, power loss, loss of speed, hard starting and
generally poor engine performance.  Follow the
scheduled maintenance service recommendations to
ensure satisfactory spark plug performance.  Refer to
Maintenance and Lubrication section.
Normal spark plug operation will result in brown to
grayish-tan deposits appearing on the insulator portion of
the spark plug.  A small amount of red-brown, yellow, and
white powdery material may also be present on the
insulator tip around the center electrode.  These deposits
are normal combustion by-products of fuels and
lubricating oils with additives.  Some electrode wear will
also occur.  Engines which are not running properly are
often referred to as “misfiring.”  This means the ignition
spark is not igniting the air/fuel mixture at the proper time.
While other ignition and fuel system causes must also be
considered, possible causes include ignition system
conditions which allow the spark voltage to reach ground
in some other manner than by jumping across the air gap
at the tip of the spark plug, leaving the air/fuel mixture
unburned.  Refer to 

DTC P0300.  Misfiring may also occur

when the tip of the spark plug becomes overheated and
ignites the mixture before the spark jumps. This is
referred to as “pre-ignition.”
Spark plugs may also misfire due to fouling, excessive
gap, or a cracked or broken insulator.  If misfiring occurs
before the recommended replacement interval, locate
and correct the cause.
Carbon fouling of the spark plug is indicated by dry, black
carbon (soot) deposits on the portion of the spark plug in
the cylinder.   Excessive idling and slow speeds under
light engine loads can keep the spark plug temperatures
so low that these deposits are not burned off. Very rich
fuel mixtures or poor ignition system output may also be
the cause.  Refer to DTC P0172.
Oil fouling of the spark plug is indicated by wet oily
deposits on the portion of the spark plug in the cylinder,
usually with little electrode wear.  This may be caused by
oil during break-in of new or newly overhauled engines.
Deposit fouling of the spark plug occurs when the normal
red-brown, yellow or white deposits of combustion by
products become sufficient to cause misfiring.  In some
cases, these deposits may melt and form a shiny glaze on
the insulator around the center electrode.  If the fouling is
found in only one or two cylinders, valve stem clearances
or intake valve seals may be allowing excess lubricating
oil to enter the cylinder, particularly if the deposits are
heavier on the side of the spark plug facing the intake
valve.

SECTION

6E–462

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

TS23995

Excessive gap means that the air space between the
center and the side electrodes at the bottom of the spark
plug is too wide for consistent firing.  This may be due to
improper gap adjustment or to excessive wear of the
electrode during use. A spark plug gap that is too small
may cause an unstable idle condition.  Excessive gap
wear  can be an indication of continuous operation at high
speeds or with engine loads, causing the spark to run too
hot.  Another possible cause is an excessively lean fuel
mixture.

TS23992

Low or high spark plug installation torque or improper
seating can result in the spark plug running too hot and
can cause excessive center electrode wear.  The plug
and the cylinder head seats must be in good contact for
proper heat transfer and spark plug cooling.  Dirty or
damaged threads in the head or on the spark plug can
keep it from seating even though the proper torque is
applied.  Once spark plugs are properly seated, tighten
them to the torque shown in the Specifications Table.  Low
torque may result in poor contact of the seats due to a
loose spark plug.  Overtightening may cause the spark
plug shell to be stretched and will result in poor contact

between the seats.  In extreme cases,  exhaust blow-by
and damage beyond simple gap wear may occur.
Cracked or broken insulators may be the result of
improper installation, damage during spark plug
re-gapping, or heat shock to the insulator material.  Upper
insulators can be broken when a poorly fitting tool is used
during installation or removal, when the spark plug is hit
from the outside, or is dropped on a hard surface. Cracks
in the upper insulator may be inside the shell and not
visible. Also, the breakage may not cause problems until
oil or moisture penetrates the crack later.

TS23994

A/C Clutch Diagnosis

A/C Clutch Circuit Operation

A 12-volt signal is supplied to the A/C request input of the
PCM when the A/C is selected through the A/C control
switch.
The A/C compressor clutch relay is controlled through the
PCM.  This allows the PCM to modify the idle air control
position prior to the A/C clutch engagement for better idle
quality.  If the engine operating conditions are within their
specified calibrated acceptable ranges, the PCM will
enable the A/C compressor relay.  This is done by
providing a ground path for the A/C relay coil within the
PCM.  When the A/C compressor relay is enabled,
battery voltage is supplied to the compressor clutch coil.
The PCM will enable the A/C compressor clutch
whenever the engine is running and the A/C has been
requested.  The PCM will not enable the A/C compressor
clutch if any of the following conditions are met:

D

The throttle is greater than  90%.

D

The engine speed is greater than 6315 RPM.

D

The ECT is greater than 119

°

C (246

°

F).

D

The IAT is less than 5

°

C (41

°

F).

D

The throttle is more than 80% open.

A/C Clutch Circuit Purpose

The A/C compressor operation is controlled by the
powertrain control module (PCM) for the following
reasons:

SECTION

 

 

 

 

 

 

 

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