Opel Frontera UE. Manual - part 195

6E1–78

X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Fuel System Diagnosis

 

Step

Action

Value(s)

Yes

No

1

Was the ”On–Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2 

Go to OBD

System

Check 

2

1. Turn the ignition OFF.
2. Turn the air conditioning system OFF.
3. Relieve fuel system pressure and install the fuel

pressure gauge.

4. Turn the ignition ON.

NOTE: The fuel pump will run for approximately 2
seconds. Use the Tech 2 to command the fuel pump
ON.

5. Observe the fuel pressure indicated by the fuel

pressure gauge with the fuel pump running.

Is the fuel pressure within the specified limits?

283–376 kPa

(41–55 psi)

Go to Step 3 

Go to Step 17

3

NOTE: The fuel pressure will drop when the fuel pump
stops running, then it should stabilize and remain
constant.

Does the fuel pressure indicated by the fuel pressure
gauge remain constant?

—

Go to Step 4 

Go to Step 12

4

1. When the vehicle is at normal operating

temperature, turn the ignition ON to build fuel
pressure and observe the measurement on the
gauge.

2. Start the engine and observe the fuel pressure

gauge.

Did the reading drop by the amount specified after the
engine was started?

21–105 kPa

(3–15 psi)

Go to Step 5 

Go to Step 9 

5

Is fuel pressure dropping off during acceleration,
cruise, or hard cornering?

—

Go to Step 6 

Check for

improper fuel

6

Visually and physically inspect the following items for a
restriction:

D

The in–pipe fuel filter.

D

The fuel feed line.

Was a restrication found?

—

Verify repair

Go to Step 7 

7

Remove the fuel tank and visually and physically
inspect the following items:

D

The fuel pump strainer for a restriction.

D

The fuel line for a leak.

D

Verify that the correct fuel pump is in the vehicle.

Was a problem found in any of these areas?

—

Verify repair

Go to Step 8 

8

Replace the fuel pump.

Is the action complete?

—

Verify repair

—

9

1. Disconnect the vacuum hose from the fuel pressure

regulator.

2. With the engine idling, apply 12–14 inches of

vacuum to the fuel pressure regulator.

Does the fuel pressure indicated by the fuel pressure
gauge drop by the amount specified?

21–105 kPa

(3–15 psi)

Go to Step 10

Go to Step 11

6E1–79

X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Fuel System Diagnosis

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

Locate and repair the loss of vacuum to the fuel
pressure regulator.

Is the action complete?

—

Verify repair

—

11

Replace the fuel pressure regulator.

Is the action complete?

—

Verify repair

—

12

1. Run the fuel pump with the Tech 2.
2. After pressure has built up, turn off the pump and

clamp the supply hose shut with suitable locking
pliers which will not damage the hose.

Does the fuel pressure indicated by the fuel pressure
gauge remain constant?

—

Go to Step 13

Go to Step 15

13

Visually inspect the fuel supply line and repair any
leaks.

Was a problem found?

—

Verify repair

Go to Step 14

14

Remove the fuel tank and inspect for leaky hose or
in–tank fuel line.

Was a problem found?

—

Verify repair

Go to Step 8 

15

1. If the pliers are still clamped to the fuel supply hose,

remove the locking pliers.

2. With suitable locking pliers which will not damage

the hose, clamp the fuel return line to prevent fuel
from returning to the fuel tank.

3. Run the fuel pump with the Tech 2.
4. After pressure has built up, remove power to the

pump.

Does the fuel pressure indicated by the fuel pressure
gauge remain constant?

—

Go to Step 11

Go to Step 16

16

Locate and replace any leaking fuel injector(s).

Is the action complete?

—

Verify repair

—

17

Is the fuel pressure indicated by the fuel pressure
gauge above the specified limit?

376 kPa  (55

psi)

Go to Step 18

Go to Step 21

18

1. Relieve the fuel pressure. Refer to the Fuel

Pressure Relief. 

2. Disconnect the fuel return line from the fuel rail.
3. Attach a length of flexible hose to the fuel rail return

outlet passage.

4. Place the open end of the flexible hose into an

approved gasoline container.

5. Run the fuel pump with the Tech 2.
6. Observe the fuel pressure indicated by the fuel

pressure gauge with the fuel pump running.

Is the fuel pressure within the specified limits?

290–376 kPa

(42–55 psi)

Go to Step 19

Go to Step 20

19

Locate and correct the restriction in the fuel return line.

Is the action complete?

—

Verify repair

—

20

Visually and physically inspect the fuel rail outlet
passages for a restriction.

Was a restriction found?

—

Verify repair

Go to Step 11

6E1–80

X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Fuel System Diagnosis

  (Cont'd)

Step

No

Yes

Value(s)

Action

21

Is the fuel pressure indicated by the fuel pressure
gauge above the specified value?

0 kPa (0 psi)

Go to Step 22

Go to Step 23

22

1. Command the fuel pump ON with the Tech 2.
2. Using suitable pliers which will not damage the fuel

hose, gradually apply pressure with the pliers to
pinch the flexible fuel return hose closed.

CAUTION: Do not let the fuel pressure exceed
the second specified value.

Does the fuel pressure indicated by the fuel pressure
gauge rise above the first specified value?

414 kPa (60

psi)

Go to Step 11

Go to Step 7 

23

1. Command the fuel pump ON with the Tech 2.
2. Remove the fuel filler cap and listen for the sound of

the fuel pump running.

3. Turn the pump off.

Was the fuel pump running?

—

Go to Step 7 

Go to Fuel

System

Electrical Test

Chart 

6E1–81

X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

IDLE AIR CONTROL (IAC) SYSTEM CHECK

D06RX112

Circuit Description

The engine control module (ECM) controls engine idle
speed with the idle air control (IAC) valve. To increase idle
speed, the ECM retracts the IAC valve pintle away from
its seat, allowing more air to bypass the throttle bore. To
decrease idle speed, it extends the IAC valve pintle
towards its seat, reducing bypass air flow. A Tech 2 will
read the ECM commands to the IAC valve in counts.
Higher counts indicate more air bypass (higher idle).
Lower counts indicate less air is allowed to bypass (lower
idle).

Diagnostic Aids

A slow, unstable, or fast idle may be caused by a non-IAC
system problem that cannot be overcome by the IAC
valve.  Out of control range IAC Tech 2 counts will be

above 60 if idle is too low, and zero counts if idle is too
high.  The following checks should be made to repair a
non-IAC system problem:

D

Vacuum leak (high idle) – If idle is too high, stop the
engine.  Fully extend (low) IAC with the Tech 2.  Start
the engine.  If idle speed is above 800 RPM, locate
and correct the vacuum leak, including the PCV
system.  Check for binding of the throttle blade or
linkage.

D

Lean heated oxygen sensor signal (high air/fuel ratio)
– The idle speed may be too high or too low.  Engine
speed may vary up and down, and disconnecting the
IAC valve does not help.  Diagnostic trouble codes
P0131, P0151, P0171, may be set.  Tech 2 oxygen
(O2) voltage will be less than 100 mV (0.1 V).  Check
for low regulated fuel pressure, water in fuel, or a
restricted injector.