Content .. 2172 2173 2174 2175 ..

Opel Frontera UBS. Manual - part 2174

6E–269

ENGINE DRIVEABILITY AND EMISSIONS

Lack of Power, Sluggish or Spongy Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Check the PCM grounds for the cleanliness,

tightness and proper locations. Refer to the PCM
wiring diagrams in

Electrical Diagnosis.

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

Was a problem found?

—

Verify repair

Go to

Step 12

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 13

1. Check the torque converter clutch (TCC) for proper

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 14

1. Check for an engine mechanical problem. Check

for low compression, incorrect or worn camshaft,
loose timing belt, etc. Refer to

Engine Mechanical.

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

Was a problem found?

—

Verify repair

Go to

Step 15

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–270

ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Spark Knock Symptom

Step

Action

Value(s)

Yes

DEFINITION:
A mild to severe ping, usually worse under acceleration.
The engine makes sharp metallic knocks that change
with throttle opening.

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

If Tech 2 readings are normal (refer to

Typical Scan

Values) and there are no engine mechanical faults, fill
the fuel tank with a known quality gasoline that has a
minimum octane rating of 87 and re-evaluate the
vehicle performance.

Is detonation present?

—

Go to

Step 5

Verify repair

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 6

1. Check 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 7

1. Check for obvious overheating problems:

Low engine coolant.

Restricted air flow to radiator, or restricted
water flow through radiator.

Correct coolant solution should be a 50/50 mix
of approved antifreeze/coolant and water.
Refer to

Engine Cooling.

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

Was a problem found?

—

Verify repair

Go to

Step 8

1. Check fuel pressure. Refer to Chart Fuel System

Pressure Test.

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

Was a problem found?

—

Verify repair

Go to

Step 9

1. Check items that can cause an engine to run lean

(long term fuel trim significantly in the positive
range). For a lean condition, refer to

Diagnostic

Aids in DTC P0171 Diagnostic Support.

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

Was a problem found?

—

Verify repair

Go to

Step 10

6E–271

ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Spark Knock Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Spark plugs for proper heat range. Refer to

General

Information.

2. If incorrect spark plugs are installed, replace spark

plugs as necessary.

Did any spark plugs require replacement?

—

Verify repair

Go to

Step 11

1. Remove excessive carbon buildup with a top engine

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

2. Re-evaluate vehicle performance.

Is detonation still present?

—

Go to

Step 12

Verify repair

1. Check for an engine mechanical problem. Perform

a cylinder compression check. Refer to

Engine

Mechanical.

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

Was a problem found?

—

Verify repair

Go to

Step 13

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–272

ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

Step

Action

Value(s)

Yes

DEFINITION:
Engine runs unevenly at idle. If severe, the engine or
vehicle may shake. Engine idle speed may vary in
RPM. Either condition may be severe enough to stall
the engine.

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 13

Go to

Step 3

Was a visual/physical check performed?

—

Go to

Step 4

Go to

Visual/Physic

al Check

1. Check the PCM grounds for cleanliness, tightness

and proper routing. Refer to the PCM wiring
diagrams in

Electrical Diagnosis.

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

Was a problem found?

—

Verify repair

Go to

Step 5

Observe the long term fuel trim on Tech 2.

Is the long term fuel trim significantly in the negative
range (rich condition)?

—

Go to

Step 6

Go to

Step 7

1. Check items that can cause the engine to run rich.

Refer to

Diagnostic Aids in DTC P0172 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to

Step 9

Is the long term fuel trim significantly in the positive
range (lean condition)?

—

Go to

Step 8

Go to

Step 9

1. Check items that can cause the engine to run lean.

Refer to

Diagnostic Aids in DTC P0171 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to

Step 9

1. Check for incorrect idle speed. Ensure that the

following conditions are present:

The engine is fully warm.

The accessories are “OFF.”

2. Using Tech 2, monitor the IAC position.

Is the IAC position within the specified values?

Between 10

and 50

counts

Go to

Step 11

Go to

Step 10

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