Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 129

FU(w/o STI)-43

Manifold Absolute Pressure Sensor

FUEL INJECTION (FUEL SYSTEMS)

10.Manifold Absolute Pressure

Sensor

A: REMOVAL

1) Remove the collector cover.

2) Disconnect the ground cable from battery.

3) Disconnect the connector (A) from manifold ab-

solute pressure sensor, and remove the filter as-

sembly (B) from intake manifold.

4) Remove the manifold absolute pressure sensor

from the solenoid valve bracket.

B: INSTALLATION

Install in the reverse order of removal.
Tightening torque:

6.4 N·m (0.7 kgf-m, 4.7 ft-lb)

C: INSPECTION

1) Check that the manifold absolute pressure sen-

sor has no deformation, cracks or other damages.

2) Connect dry-cell battery positive terminal to ter-

minal No. 3 and dry-cell battery ground terminal to

terminal No. 1, circuit tester positive terminal to ter-

minal No. 2 and the circuit tester negative terminal

to terminal No. 1.

NOTE:

• Use new dry-cell batteries.

• Using circuit tester, check the voltage of a single

dry-cell battery is 1.6 V or more. And also check the

voltage of three batteries in series is between 4.8 V

and 5.2 V.

3) Check the voltage at a normal atmospheric pres-

sure.
NOTE:

The atmospheric pressure at higher altitude is low-

er than normal. Therefore, the voltage is lower than

the standard value.

4) Connect the Mighty Vac to the pressure port (A)

of manifold absolute pressure sensor.

IN-00203

(A)

FU-05757

(B)

Terminal No.

Standard

2 (+) and 1 (–)

Approx. 2.2 V

(when 25°C (77°F))

FU-04486

3 2 1

V

1.5V

1.5V

1.5V

4.8 5.2V

FU-04487

(A)

FU(w/o STI)-44

Manifold Absolute Pressure Sensor

FUEL INJECTION (FUEL SYSTEMS)

5) Check the voltage when generating vacuum and

positive pressure using Mighty Vac.
CAUTION:

Do not apply vacuum of less than –88 — 200

kPa (–0.9 — 2.04 kgf/cm

2

, –12.8 — 29.0 psi). Do-

ing so may damage the manifold absolute pres-

sure sensor.
NOTE:

When vacuum occurs at the pressure port of man-

ifold absolute pressure sensor, the voltage will drop

from the value as in step 3). When positive pres-

sure occurs, on the other hand, the voltage will rise.

Pressure

Terminal No.

Standard

–88 kPa (–0.9 kgf/cm

2

,

–12.8 psi)

2 (+) and

1 (–)

Approx. 1.0 V

(when 25°C (77°F))

152 kPa (1.55 kgf/cm

2

,

22.0 psi)

Approx. 4.5 V

(when 25°C (77°F))

FU(w/o STI)-45

Fuel Injector

FUEL INJECTION (FUEL SYSTEMS)

11.Fuel Injector

A: REMOVAL

1. RH SIDE

1) Release the fuel pressure. <Ref. to FU(w/o STI)-

65, RELEASING OF FUEL PRESSURE, PROCE-

DURE, Fuel.>

2) Disconnect the ground cable from battery.

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

cap.

4) Remove the intake manifold. <Ref. to FU(w/o

STI)-18, REMOVAL, Intake Manifold.>

5) Remove the fuel pipe protector RH from the in-

take manifold.

6) Disconnect the connector from fuel injector.

7) Remove the bolt which holds fuel injector pipe

RH onto intake manifold.

8) Remove the fuel injector.

2. LH SIDE

1) Release the fuel pressure. <Ref. to FU(w/o STI)-

65, RELEASING OF FUEL PRESSURE, PROCE-

DURE, Fuel.>

2) Disconnect the ground cable from battery.

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

cap.

4) Remove the intake manifold. <Ref. to FU(w/o

STI)-18, REMOVAL, Intake Manifold.>

IN-00203

FU-06561

FU-06548

FU-03089

FU-03094

IN-00203

FU(w/o STI)-46

Fuel Injector

FUEL INJECTION (FUEL SYSTEMS)

5) Remove the engine ground terminal from the

fuel pipe protector LH and remove the fuel pipe pro-

tector LH from the intake manifold.

6) Disconnect the connector from fuel injector.

7) Remove the bolt which holds fuel injector pipe

LH onto intake manifold.

8) Remove the fuel injector.

B: INSTALLATION

1. RH SIDE

Install in the reverse order of removal.
NOTE:

Use new O-rings, rubbers and seal rings.
Tightening torque:

19 N·m (1.9 kgf-m, 14.0 ft-lb)

FU-06540

FU-06549

FU-05752

FU-04299

FU-03091

FU-03089

FU-06550