engine SUBARU LEGACY 1995 Service Repair Manual

OBD0627
7) Read data on Subaru Select Monitor.
Designate mode use function key.
Function mode: F33, F34, F35 and F36
: Is the maximum misfire rate of each cylin-
der less than 2 %?
: Go to next.
: Go to step 3.
: The vehicle has been empty of fuel.
:
The engine has no abnormality.

Finish diagnostics operation.
: Go to next.
: Check if the cause of misfire was made
when the engine is running.
Ex. Remove spark plug cord, etc.
:
The engine has no abnormality.

Finish diagnostics operation.
: Repair poor contact in ignitor, ignition coil, fuel
injector, ECM and coupling harness connector.
3
CHECK AIR INTAKE SYSTEM.
: Check the following items.

1Are there air leaks or air suction caused
by loose or dislocated nuts and bolts?

2Are there cracks or any disconnection of
hoses?
: Repair air intake system.
: Go to step 4.
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5GROUP OF #2 AND #4 CYLINDERS
: Check the following items for #2 and #4 cyl-
inders.

Spark plugs

Fuel injectors

Skipping timing belt teeth

6THE CYLINDER AT RANDOM
: Is the engine idle rough?
: Go to next. (AT models only)
: Go to DTC P0170 [T11P3], [T11P4] and [T11P5].
NOTE:
On MT models, go to DTC P0170 [T11P3], [T11P4] and
[T11P5].
OBD0631
OBD0632
: Is the differential pressure between maxi-
mum EGR system pressure (value of func-
tion mode F37) and minimum EGR system
pressure (value of function mode F38) less
than 10 mmHg?
NOTE:
Use the values read in step 3 for function modes F37 and
F38.
: Replace EGR valve.
: Go to DTC P0170 [T11P3], [T11P4] and [T11P5].
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OBD0283
Y: DTC P0325
—KNOCK SENSOR CIRCUIT MALFUNCTION
(KNOCK)—
OBD0284A
DESCRIPTION:
The knock sensor senses engine knocks and send a volt-
age signal to the ECM depending on the degree of the
knock.
This signal information is used for spark timing learning
control to provide optimal spark timing.
The knock sensor is bolted to the cylinder block at #4 pis-
ton. It senses knocks which can occur in any cylinder. Its
components are a weight, which moves up and down when
it senses vibrations, a piezo element, which produces a
voltage, and a resistor, which senses a broken circuit (all
these are molded into a single unit). When the sensor
senses engine knocks, knocking vibration is conveyed to
the weight. The up or down movement of the weight is
applied to the piezo element as a pressure difference. The
knock sensor will then produce a voltage signal in relation
to the degree of the knock.
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Poor driving performance

Knocking occurs.
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11. Diagnostics Chart with Trouble Code

DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Engine stalls.

Failure of engine to start
1.Check harness.
2.Check crankshaft position sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:
OBD0295

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OBD0304
AA: DTC P0340
—CAMSHAFT POSITION SENSOR CIRCUIT
MALFUNCTION (CAM)—
OBD0305A
DESCRIPTION:

The camshaft position sensor is located on the left-hand
camshaft support to detect the combustion cylinder at any
one moment.

It is designed so that the ECM accurately reads the
number of pulses which occur when protrusions provided
on the back of the LH camshaft-drive sprocket cross the
sensor.
Internal construction and the basic operating principle of
the camshaft position sensor are similar to those of the
crankshaft position sensor. A total of seven protrusions
(one each at two locations, two at one location and three
at one location) are arranged in four equal parts of the
sprocket.
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Engine stalls.

Failure of engine to start
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OBD0315
AB: DTC P0400
—EXHAUST GAS RECIRCULATION FLOW
MALFUNCTION (EGR)—
DESCRIPTION:

The EGR system aims at reduction of NOx by lowering
the combustion temperature through recirculation of a part
of exhaust gas into cylinders via the intake manifold.

This system consists of the EGR valve, the EGR sole-
noid valve and BPT (Back Pressure Transducer). The EGR
valve is operated by the vacuum pressure from throttle
body via BPT and controls the exhaust gas flow from the
exhaust manifold to the intake manifold by open/close
operation of the EGR valve.
The EGR solenoid valve is controlled by the ECM accord-
ing to the engine driving condition and opens/closes the
vacuum line from the BPT to the EGR valve diaphragm.
The BPT controls the vacuum pressure to control the
amount of EGR according to the engine load.
OBD0316A
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OBD0317A

The EGR valve is situated between the exhaust manifold
and intake manifold. After opening EGR solenoid valve,
EGR valve is opened for receiving throttle port pressure on
diaphragm. Then, part of the exhaust gas is recirculated
into intake manifold.
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Poor driving performance on low engine speed
1.Check transmission type.
AT
MT
Check AT/MT identification circuit. [T11BN0].>
2.Check DTC P0105, P0106, P0403, P1102 on
display.

3.Check vacuum hose.
4.Check operation of EGR system.
Confirmation of actual driving
pattern
CAUTION:
Before confirmation of actual driving pattern, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>




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3
CHECK VACUUM HOSE.
: Check vacuum hoses for disconnection,
leakage and clogging.
: Check and repair the following items.

Two lines of pipes and hoses running between
throttle body and BPT

Pipe and hose line connecting BPT and EGR
solenoid valve

Hose between EGR solenoid valve and EGR
valve

BPT pressure transmitting hose
: Go to step 4.
4
CHECK OPERATION OF EGR SYSTEM.
1) Turn ignition switch to OFF.
2) Connect the test mode connector.
3) Turn ignition switch to ON.
: Does EGR solenoid valve produce operating
sound?
: Replace EGR solenoid valve.
: Go to next step.
4) Turn ignition switch to OFF.
5) Disconnect connector from EGR solenoid valve.
6) Connect 12 V battery’s ground
terminal to one ter-
minal of the EGR solenoid valve. Then connect 12 V bat-
tery’sterminal to the other terminal of it.
CAUTION:
Do not use the 12 V battery installed in the vehicle,
because the electrical system may be damaged.
7) Start the engine.
: Open throttle valve by 5 to 10 degrees and
visually check EGR valve operation.
: Possibly EGR valve malfunction may be due to
freezing or clogging by foreign matter. At this point
in time do not replace EGR valve, since it is not
faulty. And after the checking, go to
CONFIR-
MATION OF ACTUAL DRIVING PATTERN.
NOTE:
If malfunction is detected again in the confirmation of actual
driving pattern, EGR valve is faulty. Go to next
.
: Go to next.
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: Is there clogging in the gas outlets of intake
manifold or cylinder head, checking by
breathing into the outlets?
: Repair or replace intake manifold or cylinder
head. And go to
CONFIRMATION OF
ACTUAL DRIVING PATTERN.
: Replace EGR valve. And go toCONFIRMA-
TION OF ACTUAL DRIVING PATTERN.
CONFIRMATION OF ACTUAL DRIVING
PATTERN.
1) Conduct CLEAR MEMORY and INSPECTION MODES.

2) Connect Subaru select monitor to its data link connec-
tor.
3) Start and warm-up the engine until the radiator fan
makes one complete rotation. (All accessory switches are
OFF.)
4) Turn Subaru select monitor switch to ON.
5) Designate mode using function key.
Function mode: FA4
6) Drive at 55±3 MPH (88±5 km/h) until the LED No. 5 is
turned on.
NOTE:
Keep the throttle valve opening at the same degree, since
diagnosis will be interrupted when the opening varies.
Diagnosis starts in 190 seconds after starting engine and
takes 4 seconds.
Put the gear to“D”range for the diagnosis.
7) Designate mode using function key.
Function mode: FB0
8) Confirm the“No trouble”indication on Subaru select
monitor.
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OBD0323
AC: DTC P0403
—EXHAUST GAS RECIRCULATION CIRCUIT
MALFUNCTION (EGRSOL)—
OBD0324A
DESCRIPTION:
The EGR solenoid valve is situated between the BPT and
EGR valve. EGR solenoid valve is opened by a signal
emitted from the ECM. Therefore, throttle port pressure is
transmitted to diaphragm of EGR valve.
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Poor driving performance on low engine speed
1.Check transmission type.
AT
MT
Check AT/MT identification circuit.
2.Check output signal from ECM.

3.Check harness.
4.Check harness.
5.Check EGR solenoid valve.
6.Check power supply to EGR solenoid valve.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>




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