Opel Frontera UBS. Manual - part 2178

6E–285

ENGINE DRIVEABILITY AND EMISSIONS

Hesitation, Sag, Stumble Symptom

 

Step

Action

Value(s)

Yes

No

1

DEFINITION:
Momentary lack of response as the accelerator is
pushed down.  Can occur at any vehicle speed.  Usually
most pronounced when first trying to make the vehicle
move, as from a stop sign.  May cause the engine to stall
if severe enough.

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

1. Check the fuel control heated oxygen sensors

(HO2S, B1S1 and B2S1).  The fuel control heated
oxygen sensors (HO2S) should respond quickly to
different throttle positions.  If they don’t, check them
for silicon or other contaminants from fuel or use of
improper RTV sealant.  The sensors may have a
white powdery coating.

Silicon contamination causes a high but false
HO2S signal voltage (rich exhaust indication).
The PCM will then reduce the amount of fuel
delivered to the engine, causing a severe
driveability problem.  For more information, refer
to 

Powertrain Control Module (PCM) and Sensors.

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

Was a problem found?

—

Verify repair

Go to 

Step  5

5

1. Check the fuel pressure.  Refer to 

Fuel System

Pressure Test.

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

Was a problem found?

—

Verify repair

Go to 

Step 6

6

Observe the TP angle display on Tech 2 while slowly
increasing throttle pedal.

Does the TP angle display steadily increase from 0% at
closed throttle to 100% at WOT?

—

Go to 

Step 7

Go to 

Step 18

7

Monitor the long term fuel trim on Tech 2.

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

—

Go to 

Step 8

Go to 

Step 9

8

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 10

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 10

6E–286

ENGINE DRIVEABILITY AND EMISSIONS

Hesitation, Sag, Stumble Symptom

  (Cont'd)

Step

No

Yes

Value(s)

Action

10

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 11

11

1. Check for a loose ignition coil ground.

Refer to 

Electronic Ignition System.

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

Was a problem found?

—

Verify repair

Go to 

Step 12

12

1. Check the 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 13

13

1. Remove spark plugs and 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 14

14

1. Check the PCM grounds for clearness, 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 15

15

1. Check the MAF sensor connections.
2. If a problem is found, replace the faulty terminals as

necessary.  Refer to 

Electrical Diagnosis for wiring

repair procedures.

Was a problem found?

—

Verify repair

Go to 

Step 16

16

1. Visually/physically check vacuum hoses for splits,

kinks, and proper 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 17

6E–287

ENGINE DRIVEABILITY AND EMISSIONS

Hesitation, Sag, Stumble Symptom

  (Cont'd)

Step

No

Yes

Value(s)

Action

17

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 butter

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

18

Replace the TP sensor.

Is the action complete?

—

Verify repair

—

6E–288

ENGINE DRIVEABILITY AND EMISSIONS

Default Matrix Table

Service Procedure Default Strategy

A referral strategy has been established to assist the
technician with additional information when the cause of
the failure cannot be determined.  If no problem is found
after performing diagnostics, then refer to the default
matrix table for further diagnostic information.

Default Matrix Table

Strategy Based Diagnostic Charts

Initial Diagnosis

Default Section(s)

On-Board Diagnostic (OBD) System
Check

Vehicle does not enter diagnostics.

Chassis Electrical

On-Board Diagnostic (OBD) System
Check

Vehicle enters diagnostics and
communicates with Tech 2.  MIL is
“ON” in diagnostics.  Engine does not
start and run.

Ignition System Check

On-Board Diagnostic (OBD) System
Check

Engine starts and runs, no PCM
codes set.  Customer complains of
vibration.

—

On-Board Diagnostic (OBD) System
Check

Engine starts and runs, no PCM
codes set.  Customer complains of
harsh or soft shift, poor performance,
delayed or no engagement into drive
or reverse, transmission fluid leak,
transmission noise or vibration, or
improper TCC operation.

Automatic Transmission

PCM Power and Ground Check

On-Board Diagnostic (OBD) System
Check.

Chassis Electrical

PCM Power and Ground Check

On-Board Diagnostic (OBD) System
Check. PCM power and ground
circuits OK. Data link voltage
incorrect.

Chassis Electrical

On-Board Diagnostic (OBD) System
Check

Engine starts and runs, no PCM
codes set.  Customer complains of
harsh or soft shift, poor performance,
delayed or no engagement into drive
or reverse, transmission fluid leak,
transmission noise or vibration, or
improper TCC operation.

Automatic Transmission

Symptoms

Initial Diagnosis

Default Section(s)

Intermittents

1. On-board Diagnostic (OBD)

system check.

2. Careful visual/physical

inspections.

Chassis Electrical

Hard Starts

1. OBD system check.
2. Sensors (ECT, MAP, MAF, TP) ;

MAP output chart.

3. Fuel system electrical test, fuel

system diagnosis.

4. Ignition system.
5. IAC system check.

Engine Mechanical, Ignition
System Check, Exhaust System
Diagnosis

Surges and/or Chuggles

1. OBD system check.
2. Heated oxygen sensors.
3. Fuel system diagnosis.
4. Ignition system.

Calibration ID “Broadcast
Code”/Service Bulletins, Ignition
System Check, Generator
Output, Exhaust System
Diagnosis, 4L30-E System Test