Content .. 340 341 342 343 ..

Opel Frontera UBS. Manual - part 342

6E–274

ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Check ignition coils for cracks or carbon tracking.
2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 18

Using Tech 2, monitor the throttle position (TP) angle
with the engine idling.

Is the TP angle at the specified value and steady?

Go to

Step 19

Refer to

DTC

P0123 for

further

diagnosis

1. Check the positive crankcase ventilation (PCV)

valve for proper operation. Refer to

Crankcase

Ventilation System.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 20

1. Check the transmission range switch circuit. Use

Tech 2 and be sure Tech 2 indicates that the vehicle
is in drive with the gear selector in drive or overdrive.

2. If a problem is found, diagnose and repair the

transmission range switch as necessary (refer to
4L30-E Automatic Transmission Diagnosis).

Was a problem found?

—

Verify repair

Go to

Step 21

1. Check for the following engine mechanical items.

Refer to

Engine Mechanical for diagnosis

procedures:

EGR valve mounted backward. Compare with
a known-good vehicle.

Low compression

Sticking or leaking valves

Worn camshaft lobe(s)

Camshaft drive belt slipped or stripped

Incorrect valve timing

Worn rocker arms

Broken valve springs

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 22

1. Check for faulty motor mounts. Refer to

Engine

Mechanical for inspection of mounts.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 23

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All electrical connections within a suspected
circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Contact

Technical

Assistance

6E–275

ENGINE DRIVEABILITY AND EMISSIONS

Poor Fuel Economy Symptom

Step

Action

Value(s)

Yes

DEFINITION:
Fuel economy, as measured by an actual road test, is
noticeably lower than expected. Also, economy is
noticeably lower than it was on this vehicle at one time,
as previously shown by an actual road test.
(Non-standard tires will cause odometer readings to be
incorrect, and that may cause fuel economy to appear
poor when it is actually normal.)

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

—

Go to

Step 2

Go to

OBD

System

Check

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

—

Verify repair

Go to

Step 3

Was a visual/physical check performed?

—

Go to

Step 4

Go to

Visual/Physic

al Check

Check owner’s driving habits.

Is the A/C “ON” full time (defroster mode “ON”)?

Are tires at the correct pressure?

Are excessively heavy loads being carried?

Is acceleration too much, too often?

Was a problem found?

—

Go to

Step 5

Go to

Step 6

Review the items in Step 4 with the customer and
advise as necessary.

Is the action complete?

—

System OK

—

1. Visually/physically check: Vacuum hoses for splits,

kinks, and improper connections and routing as
shown on the “Vehicle Emission Control
Information” label.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 7

1. Remove and check the air filter element for dirt or for

restrictions. Refer to

Air Intake System.

2. Replace the air filter element if necessary.

Was a repair required?

—

Verify repair

Go to

Step 8

1. Remove spark plugs and check for wet plugs,

cracks, wear, improper gap, burned electrodes, or
heavy deposits. Refer to

Spark Plug Replacement.

NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 9

1. Check for low engine coolant level. Refer to

Engine

Cooling.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 10

6E–276

ENGINE DRIVEABILITY AND EMISSIONS

Poor Fuel Economy Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Check for an incorrect or faulty engine thermostat.

Refer to

Engine Cooling.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 11

1. Check for low engine compression. Refer to

Engine

Mechanical.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 12

1. Check the TCC operation. Refer to

4L30-E

Transmission Diagnosis.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 13

1. Check the exhaust system for possible restriction:

Inspect the exhaust system for damaged or
collapsed pipes.

Inspect the muffler for heat distress or possible
internal failure.

Check for a possible plugged three-way
catalytic converter by checking the exhaust
system back pressure. Refer to

Restricted

Exhaust System Check.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 14

Check for proper calibration of the speedometer.

Does the speed indicated on the speedometer closely
match the vehicle speed displayed on Tech 2?

—

Go to

Step 16

Go to

Step 15

Diagnose and repair an inaccurate speedometer
condition as necessary. Refer to

Vehicle Speed

Sensor in Electrical Diagnosis.

Was a problem found?

—

Verify repair

—

1. Check the air intake system and the crankcase for

air leaks. Refer to

Air Intake System and

Crankcase Ventilation System.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 17

1. Review all diagnostic procedures within this table.
2. When all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

All connections within a suspected circuit
and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 18

Perform the procedure in

Fuel System Pressure Test.

Was the fuel pressure normal?

—

Contact

Technical

Assistance

Verify repair

6E–277

ENGINE DRIVEABILITY AND EMISSIONS

Excessive Exhaust Emissions or Odors Symptom

Step

Action

Value(s)

Yes

DEFINITION:
Vehicle fails an emission test. Vehicle has excessive
“rotten egg” smell. (Excessive odors do not necessarily
indicate excessive emissions.)

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

—

Go to

Step 2

Go to

OBD

System

Check

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

—

Go to

Step 12

Go to

Step 3

Was a thorough visual/physical check performed?

—

Go to

Step 4

Go to

Visual/Physic

al Check

1. Check for vacuum leaks. Check vacuum lines,

intake manifold, throttle body, etc.

2. If a problem is found, repair as necessary.

Were any vacuum leaks located?

—

Go to

Step 12

Go to

Step 5

1. Check the fuel cap for proper installation.
2. Secure the fuel cap if necessary.

Was the fuel cap installed properly?

—

Go to

Step 6

Go to

Step 12

1. Check the fuel pressure. Perform the procedure in

Fuel System Pressure Test.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Go to

Step 12

Go to

Step 7

1. Check for a faulty, plugged, or incorrectly installed

crankcase ventilation valve; also check the
crankcase ventilation system for plugging.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Go to

Step 12

Go to

Step 8

1. Check the injector connections.
2. If any of the injectors are connected to an incorrect

cylinder, correct as necessary.

Was a problem found?

—

Go to

Step 12

Go to

Step 9

1. Perform the “Injector Coil/Balance Test” in

Fuel

Metering System.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Go to

Step 12

Go to

Step 10

1. Refer to

Engine Cooling for cooling system

diagnosis.

2. If a problem is found, repair as necessary.

Was a problem found?

—

Go to

Step 12

Go to

Step 11

1. Remove excessive carbon buildup with a top engine

cleaner. Refer to the instructions on the top engine
cleaner can.

2. Perform the exhaust emission test.

Does the vehicle pass the test?

—

System OK

Go to

Step 13

Perform the exhaust emission test.

Does the vehicle pass the test?

—

System OK

Go to

Step 13

Content .. 340 341 342 343 ..