1998 OPEL FRONTERA fuel

6E–91 ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
StepNo Ye s Va l u e ( s ) Action
10Locate and repair the loss of vacuum to the fuel
pressure regulator.
Is the action complete?
—Verify repair—
11Replace the fuel pressure regulator.
Is the action complete?
—Verify repair—
121. Run the fuel pump with Tech 2.
2. After pressure has built up, turn off the pump and
clamp the supply hose shut with suitable locking
pliers.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
—Go to Step 13Go to Step 15
13Visually inspect the fuel supply line and repair any
leaks.
Was a problem found?
—Verify repairGo to Step 14
14Remove the fuel tank and inspect for leaky hose or
in-tank fuel line.
Was a problem found?
—Verify repairGo to Step 8
151. If the pliers are still clamped to the fuel supply hose,
remove the locking pliers.
2. With suitable locking pliers, clamp the fuel return
line to prevent fuel from returning to the fuel tank.
3. Run the fuel pump with Tech 2.
4. After pressure has built up, remove power to the
pump.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
—Go to Step 11Go to Step 16
16Locate and replace any leaking fuel injector(s).
Is the action complete?
—Verify repair—
17Is the fuel pressure indicated by the fuel pressure
gauge above the specified limit?376 kPa
(55 psi)
Go to Step 18Go to Step 21
181. Relieve the fuel pressure. Refer to the Fuel
Pressure Relief.
2. Disconnect the fuel return line from the fuel rail.
3. Attach a length of flexible hose to the fuel rail return
outlet passage.
4. Place the open end of the flexible hose into an
approved gasoline container.
5. Run the fuel pump with Tech 2.
6. Observe the fuel pressure indicated by the fuel
pressure gauge with the fuel pump running.
Is the fuel pressure within the specified limits?
290-376 kPa
(42-55 psi)
Go to Step 19Go to Step 20
19Locate and correct the restriction in the fuel return line.
Is the action complete?
—Verify repair—
20Visually and physically inspect the fuel rail outlet
passages for a restriction.
Was a restriction found?
—Verify repairGo to Step 11
21Is the fuel pressure indicated by the fuel pressure
gauge above the specified value?
0kPa (0psi)Go to Step 22Go to Step 23

6E–92
ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
StepNo Ye s Va l u e ( s ) Action
221. Command the fuel pump “ON” with Tech 2.
2. Using suitable pliers which will not damage the fuel
hose, gradually apply pressure with the pliers to
pinch the flexible fuel return hose closed.
CAUTION: Do not let the fuel pressure exceed
the second specified value.
Does the fuel pressure indicated by the fuel pressure
gauge rise above the first specified value?
376 kPa
(55 psi)
414 kPa
(60 psi)
Go to Step 11Go to Step 7
231. Command the fuel pump “ON” with Tech 2.
2. Remove the fuel filler cap and listen for the sound of
the fuel pump running.
3. Turn the pump off.
Was the fuel pump running?
—Go to Step 7
Go to Fuel
System
Electrical Test
Chart

6E–93 ENGINE DRIVEABILITY AND EMISSIONS
Idle Air Control (IAC) System Check
Circuit Description
The powertrain control module (PCM) controls engine
idle speed with the idle air control (IAC) valve. To increase
idle speed, the PCM retracts the IAC valve pintle away
from its seat, allowing more air to bypass the throttle bore.
To decrease idle speed, it extends the IAC valve pintle
towards its seat, reducing by pass air flow. Tech 2 will
read the PCM commands to the IAC valve in counts.
Higher counts indicate more air bypass (higher idle).
Lower counts indicate less air is allowed to bypass (lower
idle).
Diagnostic Aids
A slow, unstable, or fast idle may be caused by a non-IAC
system problem that cannot be overcome by the IAC
valve. Out of control range IAC Tech 2 counts will be
above 60 if idle is too low, and zero counts if idle is too
high. The following checks should be made to repair a
non-IAC system problem:
Vacuum leak (high idle) – If idle is too high, stop the
engine. Fully extend (low) IAC with the Tech 2. Start
the engine. If idle speed is above 800 RPM, locate and
correct the vacuum leak, including the PCV system.
Check for binding of the throttle blade or linkage.
Lean heated oxygen sensor signal (high air/fuel ratio) –
The idle speed may be too high or too low. Engine
speed may vary up and down, and disconnecting the
IAC valve does not help. Diagnostic trouble codes
P0131, P0151, P0171, or P0174 may be set. Tech 2
oxygen (O2) voltage will be less than 100 mV (0.1 V).
Check for low regulated fuel pressure, water in fuel, or
a restricted injector.
Rich heated oxygen sensor signal (low air/fuel ratio) –
The idle speed will be too low. Tech 2 IAC counts will
usually be above 80. The system is obviously rich and
may exhibit black smoke in the exhaust.
Tech 2 O2 voltage will be fixed at about 750 mV (0.75
V). Check for high fuel pressure, or a leaking or
sticking injector. A silicon-contaminated heated
oxygen sensor will show an O2 voltage slow to
respond on Tech 2.
Throttle body – Remove the IAC valve and inspect the
bore for foreign material.
IAC valve electrical connections – IAC valve
connections should be carefully checked for proper
contact.
PCV valve – An incorrect or faulty PCV valve may
result in an incorrect idle speed. Refer to
Diagnosis,
Rough Idle, Stalling.
If intermittent poor driveability or
idle symptoms are resolved by disconnecting the IAC,
carefully recheck the connections and valve terminal
resistance, or replace the IAC.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
1. The Tech 2 is used to extend and retract the IAC
valve. Valve movement is verified by an engine
speed change. If no change in engine speed
occurs, the valve can be resettled when removed
from the throttle body.
2. This step checks the quality of the IAC movement in
step 1. Between 700 revolutions per minute (RPM)
and about 1500 RPM, the engine speed should
change smoothly with each flash of the tester light
in both extend and retract. If the IAC valve is
retracted beyond the control range (about 1500
RPM), it may take many flashes to extend the IAC
valve before engine speed will begin to drop. This
is normal on certain engines. Fully extending the
IAC may cause engine stall. This may be normal.

6E–96
ENGINE DRIVEABILITY AND EMISSIONS
Knock Sensor (KS) System Check
(Engine Knock, Poor Performance, or Poor Economy)
StepActionVa l u e ( s )Ye sNo
1Is DTC P0325 or P0327 set?
—
Go to DTC
P0325 or
DTC P0327
Go to Step 2
2Run the engine at 1500 RPM.
Is there an internal engine knock?
—Go to Step 3Go to Step 4
3Repair the mechanical problem.
Is the action complete?
—Verify repair—
41. 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?
0Go to Step 6Go to Step 7
5Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—
61. 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.”)
0Go to Step 9Go to Step 7
71. 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 m ain harness side of the connector, use th e
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 9Go to Step 8
8Repair the open black wire ground for the shield which
prevents stray electromagnetic pulses from affecting
the knock signal.
Is the action complete?
—Verify repair—
91. 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 OKGo to Step 10
10Replace 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:
EGR passages – Check for restricted or blocked EGR
passages.
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.

6E–104
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0101 MAF System Performance
D06RW103
Circuit Description
The mass air flow (MAF) sensor measures the amount of
air which passes through it into the engine during a given
time. The powertrain control module (PCM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration or high
load situation, while a small quantity or air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which can
be monitored using a Tech 2. DTC P0101 will be set if the
signal from the MAF sensor does not match a predicted
value based on throttle position and engine RPM.
Conditions for Setting the DTC
The engine is running.
No TP sensor or MAP sensor DTCs are set.
The throttle is steady, TP angle doesn’t change by
more than 1%.
System voltage is between 11.5 volts and 16 volts.
Calculated air flow is between 25 g/second and 40
g/second.
Above conditions present for at least 1 second.
MAF signal frequency indicates an airflow significantly
higher or lower than a predicted value based on throttle
position and engine RPM for a total of 12.5 seconds
over a 25-second period of time.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
The PCM calculates an airflow value based on idle air
control valve position, throttle position, RPM and
barometric pressure.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
DTC P0101 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Mis-routed harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Refer to Intermittents under service category Symptoms.
Any un-metered air may cause this DTC to set. Check for
the following:
The duct work at the MAF sensor for leaks.
An engine vacuum leak.
The PCV system for vacuum leaks.
An incorrect PCV valve.

6E–107 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0102 MAF Sensor Circuit Low Frequency
T321122
Circuit Description
The mass air flow (MAF) sensor measures the amount of
air which passes through it into the engine during a given
time. The powertrain control module (PCM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration or high
load situation, while a small quantity of air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which can
be monitored using a Tech 2. The frequency will vary
within a range of around 2500 Hz at idle to around
1900 Hz at maximum engine load. DTC P0102 will be set
if the signal from the MAF sensor is below the possible
range of a normally operating MAF sensor.
Conditions for Setting the DTC
The engine is running above 500 RPM for greater than
10 seconds.
System voltage is above 11.5 volts.
MAF signal frequency is below 1000 Hz for a total of
50-percent of the last 1000 samples monitored. A
sample is taken every cylinder event.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
The PCM calculates an air flow value based on idle air
control valve position, throttle position, RPM and
barometric pressure.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
DTC P0102 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
Check for the following conditions:
Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
Misrouted harness – Inspect the MAF sensor harness
to ensure that it is not routed too close to high voltage
wires.
Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
Tech 2 while moving connectors and wiring harnesses
related to the MAF sensor. A change in the display will
indicate the location of the fault.
Plugged intake air duct or filter element – A wide-open
throttle acceleration from a stop should cause the
mass air flow displayed on a Tech 2 to increase from
about 3-6 g/second at idle to 100 g/second or greater
at the time of the 1-2 shift. If not, check for a restriction.
If DTC P0102 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.

6E–110
ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0103 MAF Sensor Circuit High Frequency
T321122
Circuit Description
The mass air flow (MAF) sensor measures the amount of
air which passes through it into the engine during a given
time. The powertrain control module (PCM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration or high
load situation, while a small quantity of air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which can
be monitored using a Tech 2. The frequency will vary
within a range of around 2500 Hz at idle to around
9000 Hz at maximum engine load. DTC P0103 will be set
if the signal from the MAF sensor is above the possible
range of a normally operating MAF sensor.
Conditions for Setting the DTC
The engine is running above 500 RPM for more than
10 seconds.
System voltage is above 11.5 volts.
MAF signal frequency is above 10,000 Hz (10.0 kHz)
for a total of 50 percent of the last 200 samples
monitored. A sample is taken every cylinder event.
Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.
The PCM calculates an airflow value based on idle air
control valve position, throttle position, RPM and
barometric pressure.
The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for clearing the MIL/DTC
DTC P0103 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.
Diagnostic Aids
If DTC P0103 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. This step verifies that the problem is present at idle.
4. A frequency reading with the MAF sensor connector
disconnected indicates an electromagnetic
interfernce (EMI) related fault.