Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 65

ME(STI)-22

Ignition Timing

MECHANICAL

4. Ignition Timing

A: INSPECTION

CAUTION:

After warming-up, engine becomes very hot. Be

careful not to burn yourself at measurement.

1. METHOD WITH SUBARU SELECT MON-

ITOR

1) Before checking the ignition timing, check the

following item:

(1) Check the air cleaner element is free from

clogging, spark plugs are in good condition, and

hoses are connected properly.

(2) Check the malfunction indicator light does

not illuminate.

2) Warm up the engine.

3) Read the ignition timing using Subaru Select

Monitor. <Ref. to EN(H4DOTC)(diag)-41, READ

CURRENT DATA FOR ENGINE (NORMAL

MODE), OPERATION, Subaru Select Monitor.>
NOTE:

If ignition timing is out of standard, check the igni-

tion control system. Refer to “Engine Control Sys-

tem”. <Ref. to EN(H4DOTC)(diag)-2, Basic

Diagnostic Procedure.>
Ignition timing [BTDC/rpm]:

Standard

15°

±

10°/700

2. METHOD WITH TIMING LIGHT

1) Before checking the ignition timing, check the

following item:

(1) Check the air cleaner element is free from

clogging, spark plugs are in good condition, and

hoses are connected properly.

(2) Check the malfunction indicator light does

not illuminate.

2) Warm up the engine.

3) Stop the engine, and turn the ignition switch to

OFF.

4) Disconnect the ground cable from battery.

5) Remove the air intake duct. <Ref. to IN(STI)-10,

REMOVAL, Air Intake Duct.>

6) Remove the air cleaner case. <Ref. to IN(STI)-8,

REMOVAL, Air Cleaner Case.>

7) Connect the timing light to the power wire of #1

ignition coil.

8) Install the air cleaner case. <Ref. to IN(STI)-8,

INSTALLATION, Air Cleaner Case.>

9) Connect the battery ground terminal.

10) Start the engine, turn the timing light to the

crank pulley, and check the ignition timing through

the timing belt cover gauge.
NOTE:

If ignition timing is out of standard, check the igni-

tion control system. Refer to “Engine Control Sys-

tem”. <Ref. to EN(H4DOTC)(diag)-2, Basic

Diagnostic Procedure.>
Ignition timing [BTDC/rpm]:

Standard

15°

±

10°/700

11) After inspection, install the related parts in the

reverse order of removal.

IN-00203

IN-00203

ME(STI)-23

Intake Manifold Vacuum

MECHANICAL

5. Intake Manifold Vacuum

A: INSPECTION

1) Warm up the engine.

2) Disconnect the brake booster vacuum hose from the intake manifold, and attach the vacuum gauge.

3) Keep the engine at idle speed and read the vacuum gauge indication.
NOTE:

Condition of engine inside can be diagnosed by observing the behavior of the vacuum gauge needle as de-

scribed in table below.
Intake manifold vacuum (at idling, A/C OFF):

Standard

–65.3 kPa (–490 mmHg, –19.29 inHg) or more

4) After inspection, install the related parts in the reverse order of removal.

ME-00008

Diagnosis of engine condition by inspection of intake manifold vacuum

Vacuum gauge needle behavior

Possible engine condition

1. Needle is steady but lower than standard value. This ten-
dency becomes more evident as engine temperature rises.

Leakage around intake manifold gasket, disconnection or dam-
age of vacuum hose

2. Needle intermittently drops to position lower than standard
value.

Leakage around cylinder

3. Needle drops suddenly and intermittently from standard
value.

Sticky valve

4. When engine speed is gradually increased, needle begins to
vibrate rapidly at certain speed, and then vibration increases as
engine speed increases.

Weak or broken valve springs

5. Needle vibrates above and below standard value in narrow
range.

Defective ignition system

ME(STI)-24

Engine Oil Pressure

MECHANICAL

6. Engine Oil Pressure

A: INSPECTION

1) Disconnect the ground cable from battery.

2) Remove the oil pressure switch. <Ref. to

LU(STI)-22, REMOVAL, Oil Pressure Switch.>

3) Install the oil pressure gauge to cylinder block.

4) Connect the battery ground terminal.

5) Start the engine, and check the oil pressure.
NOTE:

• Standard value is based on an engine oil temper-

ature of 80°C (176°F).

• If the oil pressure is out of specification, check oil

pump, oil filter and lubrication line. <Ref. to

LU(STI)-32, INSPECTION, Engine Lubrication

System Trouble in General.>

• If the oil pressure warning light is ON and oil

pressure is within specification, check the oil pres-

sure switch. <Ref. to LU(STI)-32, INSPECTION,

Engine Lubrication System Trouble in General.>
Engine oil pressure:

Standard

98 kPa (1.0 kgf/cm

2

, 14 psi) or more

(at 600 rpm)

392 kPa (4.0 kgf/cm

2

, 57 psi) or more

(at 6,000 rpm)

6) After inspection, install the related parts in the

reverse order of removal.

IN-00203

ME-03698

IN-00203

ME(STI)-25

Fuel Pressure

MECHANICAL

7. Fuel Pressure

A: INSPECTION

CAUTION:

• Before removing the fuel pressure gauge, re-

lease the fuel pressure.

• Be careful not to spill fuel.

• Catch the fuel from hoses using a container

or cloth.

1) Release the fuel pressure. <Ref. to FU(STI)-67,

RELEASING OF FUEL PRESSURE, PROCE-

DURE, Fuel.>

2) Open the fuel filler lid and remove the fuel filler

cap.

3) Disconnect the fuel delivery hose from the fuel

delivery pipe, and connect the fuel pressure gauge.
CAUTION:

• Be careful not to spill fuel.

• Catch the fuel from hoses using a container

or cloth.

(1) Attach ST to the fuel delivery pipe and push

ST in the direction of arrow mark to disconnect

the quick connector of the fuel delivery hose.

ST 42099AE000 QUICK CONNECTOR RE-

LEASE

(2) Connect the fuel pressure gauge with ST1

and ST2.

NOTE:

ST1 is a SUBARU genuine part.

ST1 42075AG690 FUEL HOSE

ST2 18471AA000

FUEL PIPE ADAPTER

4) Start the engine.

5) Check the fuel pressure while disconnecting

pressure regulator vacuum hose from intake mani-

fold.
NOTE:

• The fuel pressure gauge registers 10 to 20 kPa

(0.1 to 0.2 kgf/cm

2

, 1 to 3 psi) higher than standard

values during high-altitude operations.

• If the fuel pressure is out of specification, check

or replace the fuel pump, fuel line, pressure regula-

tor & damper assembly, and pressure regulator

vacuum hose.
Fuel pressure:

Standard

284 — 314 kPa

(2.9 — 3.2 kgf/cm

2

, 41 — 46 psi)

6) After connecting the vacuum hose to the pres-

sure regulator, check the fuel pressure again.
NOTE:

• The fuel pressure gauge registers 10 to 20 kPa

(0.1 to 0.2 kgf/cm

2

, 1 to 3 psi) higher than standard

values during high-altitude operations.

• If the fuel pressure is out of specification, check

or replace the fuel pump, fuel line, pressure regula-

tor & damper assembly, and pressure regulator

vacuum hose.
Fuel pressure:

Standard

230 — 260 kPa

(2.4 — 2.7 kgf/cm

2

, 33 — 38 psi)

7) After inspection, install the related parts in the

reverse order of removal.

ME-05988

ST

ME-05989

ST2

ST1