1996 SUBARU LEGACY spark plugs

3. Engine Idle Speed
A: MEASUREMENT
1) Before checking idle speed, check the following:
(1) Ensure that air cleaner element is free from
clogging, ignition timing is correct, spark plugs are in
good condition, and that hoses are connected properly.
(2) Ensure that malfunction indicator light (CHECK
ENGINE light) does not illuminate.
2) Warm-up the engine.
G2M0096
3) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
CAUTION:
When connecting Subaru Select Monitor, turn ignition
switch to OFF.
4) Start the engine and measure engine speed.
NOTE:
Engine speed is indicated on Subaru Select Monitor by
selecting “MODE F04”.
G2M0097
NOTE:

When using the OBD-II general scan tool, carefully read
its operation manual.

When Subaru Select Monitor is not used, attach the
pickup sensor on tachometer (Secondary pickup type) to
#1 cylinder spark plug cord.

This ignition system provides simultaneous ignition for
#1 and #2 plugs. It must be noted that some tachometers
may register twice that of actual engine speed.
5) Check idle speed when unloaded. (With headlights,
heater fan, rear defroster, radiator fan, air conditioning, etc.
OFF)
Idle speed (No load and gears in neutral (MT) or N or
P (AT) position):
700±100 rpm
6) Check idle speed when loaded. (Turn air conditioning
switch to “ON” and operate compressor for at least one
minute before measurement.)
Idle speed [A/C“ON”, no load and gears in neutral
(MT) or N or P (AT) position]:
850±50 rpm
CAUTION:
Never rotate idle adjusting screw. If idle speed is out
of specifications, refer to General On-board Diagnosis
Table under “2-7 On-Board Diagnostics II System”.
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2-2
3. Engine Idle Speed

4. Engine Compression
A: MEASUREMENT
1. 2200 cc MODEL
1) After warming-up the engine, turn ignition switch to
OFF.
2) Make sure that the battery is fully charged.
3) Remove all the spark plugs.
4) Disconnect connectors from fuel injectors.
5) Fully open throttle valve.
6) Check the starter motor for satisfactory performance
and operation.
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7) Hold the compression gauge tight against the spark
plug hole.
CAUTION:
When using a screw-in type compression gauge, the
screw (put into cylinder head spark plug hole) should
be less than 18 mm (0.71 in) long.
8) Crank the engine by means of the starter motor, and
read the maximum value on the gauge when the pointer is
steady.
9) Perform at least two measurements per cylinder, and
make sure that the values are correct.
Compression (200—300 rpm and fully open throttle):
Standard
1,079—1,275 kPa
(11.0—13.0 kg/cm
2, 156—185 psi)
Limit
883 kPa (9.0 kg/cm
2, 128 psi)
Difference between cylinders
196 kPa (2.0 kg/cm
2, 28 psi)
2. 2500 cc MODEL
CAUTION:
After warming-up, engine becomes very hot. Be care-
ful not to burn yourself during measurement.
1) After warming-up the engine, turn ignition switch to
OFF.
2) Make sure that the battery is fully charged.
3) Remove all the spark plugs. [W3E0].>
4) Disconnect connectors from fuel injectors.
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2-2
4. Engine Compression

TROUBLE
Engine will not start.
Rough idle and engine stall
Low output, hesitation and poor acceleration
Surging
Engine does not return to idle.
Dieseling (Run-on)
After burning in exhaust system
Knocking
Excessive engine oil consumption
Excessive fuel consumption Starter does not turn.
Initial combustion does not occur.
Initial combustion occurs.
Engine stalls after initial combustion.
INTAKE SYSTEM
2111 3Loosened or cracked intake air pipe
3111 3 1Loosened or cracked blow-by hose
31211 2Loosened or cracked vacuum hose
22222Defective intake manifold gasket
22222Defective throttle body gasket
322 2 2Defective PCV valve
222 323Loosened oil filler cap
3312 1Dirty air cleaner element
FUEL LINE
13 322Defective fuel pump and relay
33322Clogged fuel line
222233Lack of or insufficient fuel
BELT
222Defective
222322 22 2Defective timing
FRICTION
3Seizure of crankshaft and connecting rod bearing
3Seized camshaft
3Seized or stuck piston and cylinder
COMPRESSION
333222 23 2Defective hydraulic lash adjuster
333223 3 3Loosened spark plugs or defective gasket
333223 3 3Loosened cylinder head bolts or defective gasket
333223 2 2Improper valve seating
333333 3 13Defective valve stem
222223 3 3Worn or broken valve spring
333233 3 12Worn or stuck piston rings, cylinder and piston
222111 12 2Incorrect valve timing
222222Improper engine oil (low viscosity)
76
2-3DIAGNOSTICS
1. Engine Trouble in General

TROUBLE
Engine will not start.
Rough idle and engine stall
Low output, hesitation and poor acceleration
Surging
Engine does not return to idle.
Dieseling (Run-on)
After burning in exhaust system
Knocking
Excessive engine oil consumption
Excessive fuel consumption Starter does not turn.
Initial combustion does not occur.
Initial combustion occurs.
Engine stalls after initial combustion.
INTAKE SYSTEM
2111 3Loosened or cracked intake air pipe
3111 3 1Loosened or cracked blow-by hose
31211 2Loosened or cracked vacuum hose
22222Defective intake manifold gasket
22222Defective throttle body gasket
322 2 2Defective PCV valve
222 323Loosened oil filler cap
3312 1Dirty air cleaner element
FUEL LINE
13 322Defective fuel pump and relay
33322Clogged fuel line
222233Lack of or insufficient fuel
BELT
222Defective
222322 22 2Defective timing
FRICTION
3Seizure of crankshaft and connecting rod bearing
3Seized camshaft
3Seized or stuck piston and cylinder
COMPRESSION
333222 23 2Defective hydraulic lash adjuster
333223 3 3Loosened spark plugs or defective gasket
333223 3 3Loosened cylinder head bolts or defective gasket
333223 2 2Improper valve seating
333333 3 13Defective valve stem
222223 3 3Worn or broken valve spring
333233 3 12Worn or stuck piston rings, cylinder and piston
222111 12 2Incorrect valve timing
222222Improper engine oil (low viscosity)
76
2-3bDIAGNOSTICS
1. Engine Trouble in General

3. Spark Plug
A: REMOVAL AND INSTALLATION
CAUTION:
All spark plugs installed on an engine, must be of the
same heat range.
Spark plug:
CHAMPION: RC10YC4
(Alternate)
NGK: BKR6E-11
NIPPONDENSO: K20PR-U11
1) Remove spark plug cords by pulling boot, not cord itself.
2) Remove spark plugs.
3) When installing spark plugs on cylinder head, use spark
plug wrench.
Tightening torque (Spark plug):
20.6±2.9 N⋅m (2.10±0.30 kg-m, 15.19±2.14 ft-lb)
CAUTION:
The above torque should be only applied to new spark
plugs without oil on their threads.
In case their threads are lubricated, the torque should
be reduced by approximately 1/3 of the specified
torque in order to avoid their over-stressing.
4) Connect spark plug cords.
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B: INSPECTION
Check electrodes and inner and outer porcelain of plugs,
noting the type of deposits and the degree of electrode
erosion.
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1) Normal
Brown to grayish-tan deposits and slight electrode wear
indicate correct spark plug heat range.
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6-1SERVICE PROCEDURE
3. Spark Plug

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2) Carbon fouled
Dry fluffy carbon deposits on insulator and electrode are
mostly caused by slow speed driving in city, weak ignition,
too rich fuel mixture, dirty air cleaner, etc.
It is advisable to replace with plugs having hotter heat
range.
G6M0089
3) Oil fouled
Wet black deposits show excessive oil entrance into com-
bustion chamber through worn rings and pistons or exces-
sive clearance between valve guides and stems. If same
condition remains after repair, use a hotter plug.
G6M0090
4) Overheating
White or light gray insulator with black or gray brown spots
and bluish burnt electrodes indicate engine overheating.
Moreover, the appearance results from incorrect ignition
timing, loose spark plugs, wrong selection of fuel, hotter
range plug, etc. It is advisable to replace with plugs having
colder heat range.
G6M0091
C: CLEANING AND REGAPPING
Clean spark plugs in a sand blast type cleaner.
Avoid excessive blasting. Clean and remove carbon or
oxide deposits, but do not wear away porcelain.
If deposits are too stubborn, discard plugs.
After cleaning spark plugs, recondition firing surface of
electrodes with file. Then correct the spark plug gap using
a gap gauge.
Spark plug gap: L
1.0—1.1 mm (0.039—0.043 in)
D: REMOVAL AND INSTALLATION (2500 cc
EXCEPT OUTBACK MODEL)
CAUTION:
All spark plugs installed on an engine, must be of the
same heat range.
Spark plug:
NGK: PFR5B-11
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6-1SERVICE PROCEDURE
3. Spark Plug

B6M0563A
6) Remove #4 spark plug cord by pulling boot, not cord
itself.
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7) Remove spark plug with the spark plug socket.
8) Installation is in the reverse order of removal.
Tightening torque (Spark plug):
20.6±2.9 N⋅m (2.10±0.30 kg-m, 15.19±2.14 ft-lb)
CAUTION:
The above torque should be only applied to new spark
plugs without oil on their threads.
In case their threads are lubricated, the torque should
be reduced by approximately 1/3 of the specified
torque in order to avoid over-stressing.
E: REMOVAL (2500 cc OUTBACK MODEL)
CAUTION:
All spark plugs installed on an engine, must be of the
same heat range.
Spark plug:
NGK: PFR5B-11
G6M0095
1. #1 SPARK PLUG
1) Disconnect battery ground cable.
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6-1SERVICE PROCEDURE
3. Spark Plug

B6M0574
6) Re-insert the tools disconnected in step 3) into plug
hole, and set them again over the spark plug.
7) Set extension and ratchet in turn onto the connected
tools in plug hole, and tighten spark plug to the specified
torque.
Tightening torque (spark plug):
20.6±2.9 N⋅m (2.10±0.30 kg-m, 15.19±2.14 ft-lb)
CAUTION:
The above torque should be only applied to new spark
plugs without oil on their threads.
In case their threads are lubricated, the torque should
be reduced by approximately 1/3 of the specified
torque in order to avoid over-stressing.
8) The subsequent procedures are in reverse order of #1
spark plug removal.
2. #2 SPARK PLUG
CAUTION:
When installing spark plug, cover the ATF cooling
pipes with a rag to prevent damage.
1) Carry out steps 1), 2), 3), 4), 6) and 7) of #1 spark plug
installation procedure.
2) Proceed in reverse order of #2 spark plug removal.

3. #3 SPARK PLUG
1) Carry out steps 1) through 7) of #1 spark plug installa-
tion procedure.
2) Proceed in reverse order of #3 spark plug removal.

4. #4 SPARK PLUG
CAUTION:
When installing spark plug, cover the ATF cooling
pipes with a rag to prevent damage.
1) Carry out steps 1), 2), 3), 4), 6) and 7) of #1 spark plug
installation procedure.
2) Proceed in reverse order of #4 spark plug removal.

B6M0160
4. Ignition Coil
A: REMOVAL AND INSTALLATION
1) Disconnect battery ground cable.
2) Disconnect connector from ignition coil.
3) Remove ignition coil.
4) Installation is in the reverse order of removal.
CAUTION:
Be sure to connect wires to their proper positions.
Failure to do so will damage unit.
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6-1SERVICE PROCEDURE
3. Spark Plug - 4. Ignition Coil