Opel Frontera UBS. Manual - part 1226

6E–270

ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Spark Knock Symptom

 

Step

Action

Value(s)

Yes

No

1

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

2

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

3

Was a visual/physical check performed?

—

Go to 

Step 4

Go to

Visual/Physic

al Check

4

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

5

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

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

7

1. Check for obvious overheating problems:

D

Low engine coolant.

D

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

D

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

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

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

No

Yes

Value(s)

Action

10

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

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

12

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

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:

D

Visual/physical inspection

D

Tech 2 data

D

Freeze Frame data/Failure Records buffer

D

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

No

1

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

2

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

3

Was a visual/physical check performed?

—

Go to 

Step 4

Go to

Visual/Physic

al Check

4

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

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

6

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

7

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

—

Go to 

Step 8

Go to 

Step 9

8

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

9

1. Check for incorrect idle speed.  Ensure that the

following conditions are present:

D

The engine is fully warm.

D

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

6E–273

ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

1. Visually/physically inspect for the following

conditions:

D

Restricted air intake system.  Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

D

Throttle body.  Check for objects blocking the
IAC passage or throttle bore, excessive
deposits in the IAC passage and on the IAC
pintle, and excessive deposits in the throttle
bore and on the throttle plate.

D

Large vacuum leak.  Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty crankcase
ventilation valve or a disconnected brake
booster hose.

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

Was a problem found?

—

Verify repair

Go to 

Step 8

11

Check the injector connections.  If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.

Was a problem found?

—

Verify repair

Go to 

Step 12

12

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

Fuel

Metering System.

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

Was a problem found?

—

Verify repair

Go to 

Step 13

13

1. Check for fuel in the pressure regulator vacuum

hose.

2. If fuel is present, replace the fuel pressure regulator

assembly.  Refer to 

Fuel Metering System.

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

Was a problem found?

—

Verify repair

Go to 

Step 14

14

1. Check for proper ignition voltage output with spark

tester J 26792 (ST-125).  Refer to 

Electronic Ignition

System for the procedure.

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

Was a problem found?

—

Verify repair

Go to 

Step 15

15

1. Remove spark plugs.  Check for wet plugs, cracks,

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

Electronic Ignition System.

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 16

16

1. Check for a loose ignition coil ground.

Refer to 

Electrical Ignition System.

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

Was a problem found?

—

Verify repair

Go to 

Step 17