Opel Frontera UBS. Manual - part 297

 

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Opel Frontera UBS. Manual - part 297

 

 

6E–94

ENGINE DRIVEABILITY AND EMISSIONS

Idle Air Control (IAC) System Check

 

Step

Action

Value(s)

Yes

No

1

1. Ignition “OFF.”
2. Connect the Tech 2.
3. Set the parking brake.
4. Block the wheels.
5. Turn the air conditioning “OFF.”
6. Idle the engine in Park (A/T) or Neutral (M/T).
7. Operate the IAC test.
8. The engine speed should decrease and increase as

the IAC is cycled.

Does the RPM change?

Go to 

Step 2

Go to 

Step 3

2

RPM should change smoothly.

Does the RPM change within the range specified?

700-1500

RPM

Go to 

Step 3

3

Check the IAC passages.

Are the IAC passages OK?

Go to 

Step 4

Go to 

Step 5

4

Clear any obstruction from the IAC passages.

Is the action complete?

Verify repair

5

Replace the IAC.  Refer to 

On-Vehicle Service, Idle Air

Control Valve.

Is the action complete?

Verify repair

6E–95

ENGINE DRIVEABILITY AND EMISSIONS

Knock Sensor (KS) System Check 

(Engine Knock, Poor Performance, or Poor Economy)

D06RW035

Circuit Description

The knock sensor (KS) sends an AC voltage signal to the
powertrain control module (PCM).  As the KS detects
engine knock, the signal to the PCM changes in amplitude
and frequency.  The PCM retards timing if the engine
speed is over 900 RPM.

Diagnostic Aids

If the KS system checks OK, but detonation is the
complaint, refer to 

Diagnosis, Detonation/Spark Knock.

Test Description

The numbers below refer to the step numbers on the
Diagnostic Chart.
9. The change in signal speed depends on how hard

the tapping is done.  Normally there is about 1.5 to
10 mV at PCM pin A2 with the engine off.  Loud
tapping should be able to make the reading jump to
20-25 mV AC.

6E–96

ENGINE DRIVEABILITY AND EMISSIONS

Knock Sensor (KS) System Check 

(Engine Knock, Poor Performance, or Poor Economy)

 

Step

Action

Value(s)

Yes

No

1

Is DTC P0325 or P0327 set?

Go to 

DTC

P0325 or

DTC P0327

Go to 

Step 2

2

Run the engine at 1500 RPM.

Is there an internal engine knock?

Go to 

Step 3

Go to 

Step 4

3

Repair the mechanical problem.

Is the action complete?

Verify repair

4

1. Install Tech 2.
2. Turn the ignition “ON.”
3. Cycle through the list until “Knock Retard” is

displayed.

Is knock retard at the specified value?

0

°

Go to 

Step 6

Go to 

Step 7

5

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.  Refer to

UBS 98model year Immobilizer

Workshop Manual.

Is the action complete?

Verify repair

6

1. Start the engine.
2. Monitor the knock retard display on Tech 2 while

changing the throttle setting to place different loads
on the engine.

Is knock retard at the specified value? (Turn the ignition
“OFF.”)

0

°

Go to 

Step 9

Go to 

Step 7

7

1. At the rear of the engine, behind the rear fuel

injector on the lift side, disconnect the 2-wire knock
sensor harness connector.

2. Attach the positive lead of DVM to B+.
3. On the main harness side of the connector, use the

negative lead of the DVM to probe the connector pin
that is connected to the black wire.

Dose the DVM indicate the specified value?
(Reconnect the knock sensor harness.)

B+

Go to 

Step 9

Go to 

Step 8

8

Repair the open black wire ground for the shield which
prevents stray electromagnetic pulses from affecting
the knock signal.

Is the action complete?

Verify repair

9

1. Reconnect the wire harness.
2. Set a DVM to AC voltage.
3. With the DVM, backprobe the PCM connector at

A2.

4. Tap the engine lift brackprobe with a socket

extension.

Did the DVM show an increase in AC voltage while
tapping on the lift bracket?

System OK

Go to 

Step 10

10

Replace the knock sensor.

Is the action complete?

Verify repair

6E–97

ENGINE DRIVEABILITY AND EMISSIONS

Exhaust Gas Recirculation (EGR) System Check

D06RW106

Circuit Description

A properly operation exhaust gas recirculation (EGR)
system will directly affect the air/fuel requirements of the
engine.  Since the exhaust gas introduced into the air/fuel
mixture is an inert gas (contains very little or no oxygen),
less fuel is required to maintain a correct air/fuel ratio.
Introducing exhaust gas into the combustion chamber
lowers combustion temperatures and reduces the
formation of oxides of nitrogen (NOx) in the exhaust gas.
Lower combustion temperatures also prevent detonation.
If the EGR pintle were to stay closed, the inert exhaust
gas would be replaced with air and the air/fuel mixture
would be leaner.  The powertrain control module (PCM)
would compensate for the lean condition by adding fuel,
resulting in higher long term fuel trim values.

Diagnostic Aids

The EGR valve chart is a check of the EGR system.  An
EGR pintle constantly in the closed position could cause
detonation and high emissions of NOx.  It could also result
in high long term fuel trim values in the open throttle cell,
but not in the closed throttle cell.  An EGR pintle
constantly in the open position would cause a rough idle.
Also, an EGR mounted incorrectly (rotated 180

°

) could

cause rough idle.  Check for the following items:

D

EGR passages – Check for restricted or blocked EGR
passages.

D

Manifold absolute pressure sensor – A manifold
absolute pressure sensor may shift in calibration
enough to affect fuel delivery.  Refer to 

Manifold

Absolute Pressure Output Check.

 

 

 

 

 

 

 

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