ISUZU AXIOM 2002 Service Repair Manual

6E±114
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Electric Throttle Control (ETC) System Check

 
StepNo Ye s Value(s) Action
61. Install the Tech 2
2. Ignition ªONº but not engine run.
3. Chech the valve for APS and TPS.
Was the problem found?Idle AP1 =
11±13% AP2
= 87±88%
AP3 =
87±88% TP1
= 1±6% TP2
= 1±6% WOT
AP1 =
85±89% AP2
= 11±15%
AP3 =
32±36% TP1
= 98±100%
TP2 =
98±100%
Go to Step 10Go to Step 7
7Replace the throttle valve.
Is the action complete?
ÐGo to Step 8Ð
8Check the following circuits for an open, short to
voltage, short to ground, or poor connection at the
PCM:

Accelerator position sensor 1 circuit.

Accelerator position sensor 2 circuit.

Accelerator position sensor 3 circuit.

Accelerator position sensor resistance.
If a problem is found, repair as necessary.
Was a problem found?
Vcc±GND
4±6k

SIG±GND
change
resistance
Verify repairGo to Step 9
9Replace the accelerator position sensor.
Is the action complete?
ÐGo to Step 10±
10Following below the DTCs stored:
P1125, P1290, P1295, P1299
Ð
Go to
applicable
DTC chart
Go to Step 11
11Following below the DTCs stored:
P1514, P1515, P1516, P1523, P1271, P1272, P1273
Ð
Go to
applicable
DTC chart
Go to Step 12
12Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
On-Vehicle Service in
Powertrain Control Module and Sensors for
procedures.
And also refer to latest Service Bulletin.
Check to see if the Latest software is released or not.
And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.
Is the action complete?
ÐVerify repairÐ

6E±115
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis
140R200004
Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Pump and Sender Assembly
(5) Fuel Filter
(6) Fuel Rail Right
(7) Right Bank
(8) Fuel Rail Left
(9) Left Bank(10) Fuel Pressure Control Valve
(11) Common Chamber
(12) Purge Duty Solenoid Valve
(13) Throttle Valve
(14) Canister
(15) Vent Hose
(16) Vent Solenoid Valve
(17) Separator
(18) Shut off Valve (With Over Pressure Relief
Valve)

6E±116
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Circuit Description
When the ignition switch is turned ªONº, the powertrain
control module (PCM) will turn ªONº the in-tank fuel
pump. The in-tank fuel pump will remain ªONº as long as
the engine is cranking or running and the PCM is receiving
58X crankshaft position pulses. If there are no 58X
crankshaft position pulses, the PCM will turn the in-tank
fuel pump ªOFFº 2 seconds after the ignition switch is
turned ªONº or 2 seconds after the engine stops running.
The in-tank fuel pump is an electric pump within an
integral reservoir. The in-tank fuel pump supplies fuel
through an in-line fuel filter to the fuel rail assembly. The
fuel pump is designed to provide fuel at a pressure above
the pressure needed by the fuel injectors. A fuel pressure
regulator, attached to the fuel rail, keeps the fuel available
to the fuel injectors at a regulated pressure. Unused fuel
is returned to the fuel tank by a separate fuel return line.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Connect the fuel pressure gauge to the fuel feed line
as shown in the fuel system illustration. Wrap a
shop towel around the fuel pressure connection in
order to absorb any fuel leakage that may occur
when installing the fuel pressure gauge. With the
ignition switch ªONº and the fuel pump running, the
fuel pressure indicated by the fuel pressure gauge
should be 333-376 kPa (48-55 psi). This pressure
is controlled by the amount of pressure the spring
inside the fuel pressure regulator can provide.
3. A fuel system that cannot maintain a constant fuel
pressure has a leak in one or more of the following
areas:

The fuel pump check valve.

The fuel pump flex line.

The valve or valve seat within the fuel pressure
regulator.

The fuel injector(s).
4. Fuel pressure that drops off during acceleration,
cruise, or hard cornering may case a lean condition.
A lean condition can cause a loss of power, surging,
or misfire. A lean condition can be diagnosed using
a Tech 2. If an extremely lean condition occurs, the
oxygen sensor(s) will stop toggling. The oxygen
sensor output voltage(s) will drop below 500 mV.
Also, the fuel injector pulse width will increase.
IMPORTANT:Make sure the fuel system is not
operating in the ªFuel Cut-Off Modeº.
When the engine is at idle, the manifold pressure is
low (high vacuum). This low pressure (high vacuum)
is applied to the fuel pressure regulator diaphragm.
The low pressure (high vacuum) will offset the
pressure being applied to the fuel pressure regulator
diaphragm by the spring inside the fuel pressure
regulator. When this happens, the result is lower fuel
pressure. The fuel pressure at idle will vary slightly as
the barometric pressure changes, but the fuel
pressure at idle should always be less than the fuel
pressure noted in step 2 with the engine ªOFFº.16.Check the spark plug associated with a particular
fuel injector for fouling or saturation in order to
determine if that particular fuel injector is leaking. If
checking the spark plug associated with a particular
fuel injector for fouling or saturation does not
determine that a particular fuel injector is leaking,
use the following procedure:

Remove the fuel rail, but leave the fuel lines and
injectors connected to the fuel rail. Refer to
Fuel Rail
Assembly
in On-Vehicle Service.

Lift the fuel rail just enough to leave the fuel injector
nozzles in the fuel injector ports.
CAUTION: In order to reduce the risk of fire and
personal injury that may result from fuel spraying on
the engine, verify that the fuel rail is positioned over
the fuel injector ports and verify that the fuel injector
retaining clips are intact.

Pressurize the fuel system by connecting a 10 amp
fused jumper between B+ and the fuel pump relay
connector.

Visually and physically inspect the fuel injector
nozzles for leaks.
17.A rich condition may result from the fuel pressure
being above 376 kPa (55 psi). A rich condition may
cause a DTC P0132 or a DTC P0172 to set.
Driveability conditions associated with rich
conditions can include hard starting (followed by
black smoke) and a strong sulfur smell in the
exhaust.
20.This test determines if the high fuel pressure is due
to a restricted fuel return line or if the high fuel
pressure is due to a faulty fuel pressure regulator.
21.A lean condition may result from fuel pressure
below 333 kPa (48 psi). A lean condition may
cause a DTC P0131 or a DTC P0171 to set.
Driveability conditions associated with lean
conditions can include hard starting (when the
engine is cold ), hesitation, poor driveability, lack of
power, surging , and misfiring.
22.Restricting the fuel return line causes the fuel
pressure to rise above the regulated fuel pressure.
Command the fuel pump ªONº with the Tech 2. The
fuel pressure should rise above 376 kPa (55 psi) as
the fuel return line becomes partially closed.
NOTE: Do not allow the fuel pressure to exceed 414 kPa
(60 psi). Fuel pressure in excess of 414 kPa (60 psi) may
damage the fuel pressure regulator.
CAUTION: To reduce the risk of fire and personal
injury:

It is necessary to relieve fuel system pressure
before connecting a fuel pressure gauge. Refer to
Fuel Pressure Relief Procedure, below.

A small amount of fuel may be released when
disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before disconnecting, to
catch any fuel that may leak out. Place the towel in
an approved container when the procedure is
completed.

6E±117
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel Pressure Relief Procedure
1. Remove the fuel cap.
2. Remove the fuel pump relay from the underhood
relay center.
3. Start the engine and allow it to stall.
4. Crank the engine for an additional 3 seconds.
Fuel Gauge Installation
1. Remove the shoulder fitting cap.
2. Install fuel gauge J 34730-1 to the fuel feed line
located in front of and above the right side valve train
cover.
3. Reinstall the fuel pump relay.
Fuel System Diagnosis

StepActionValue(s)Ye sNo
1Was the ªOn-Board Diagnostic (OBD) System Checkº
performed?
ÐGo to Step 2
Go to OBD
System
Check
21. Turn the ignition ªOFFº.
2. Turn the air conditioning system ªOFFº.
3. Relieve fuel system pressure and install the fuel
pressure gauge.
4. Turn the ignition ªONº.
NOTE: The fuel pump will run for approximately 2
seconds. Use the Tech 2 to command the fuel pump
ªONº.
(Refer to the Miscellaneous Test.)
5. 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 3Go to Step 17
3NOTE: The fuel pressure will drop when the fuel pump
stops running, then it should stabilize and remain
constant.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
ÐGo to Step 4Go to Step 12
41. When the vehicle is at normal operation
temperature, turn the ignition ªONº to build fuel
pressure and observe the measurement on the
gauge.
2. Start the engine and observe the fuel pressure
gauge.
Did the reading drop by the amount specified after the
engine was started?
21-105 kPa
(3-15 psi)
Go to Step 5Go to Step 9
5Is fuel pressure dropping off during acceleration,
cruise, or hard cornering?
ÐGo to Step 6
Check for
improper fuel
6Visually and physically inspect the following items for a
restriction:

The in-pipe fuel filter.

The fuel feed line.
Was a restriction found?
ÐVerify repairGo to Step 7
7Remove the fuel tank and visually and physically
inspect the following items:

The fuel pump strainer for a restriction.

The fuel line for a leak.

Verify that the correct fuel pump is in the vehicle.
Was a problem found in any of these areas?
ÐVerify repairGo to Step 8

6E±118
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis

 
StepNo Ye s Value(s) Action
8Replace the fuel pump.
Is the action complete?
ÐVerify repairÐ
91. Disconnect the vacuum hose from the fuel pressure
regulator.
2. With the engine idling, apply 12-14 inches of
vacuum to the fuel pressure regulator.
Does the fuel pressure indicated by the fuel pressure
gauge drop by the amount specified?
21-105 kPa
(3-15 psi)
Go to Step 10Go to Step 11
10Locate and repair the loss of vacuum to the fuel
pressure regulator.
Is the action complete?
ÐVerify repairÐ
11Replace the fuel pressure regulator.
Is the action complete?
ÐVerify repairÐ
121. Run the fuel pump with the Tech 2.
2. After pressure has built up, turn off the pump and
clamp the supply hose shut with suitable locking
pliers which will not damage the hose.
Does the fuel pressure indicated by the fuel pressure
gauge remain constant?
ÐGo to Step 13Go to Step 15
13Visually inspect the fuel supply line and repair any
leaks.
Was a problem found?
ÐVerify repairGo to Step 14
14Remove the fuel tank and inspect for leaky hose or
in-tank fuel line.
Was a problem found?
ÐVerify 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, which will not damage
the hose, clamp the fuel return line to prevent fuel
from returning to the fuel tank.
3. Run the fuel pump with the 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?
ÐGo to Step 11Go to Step 16
16Locate and replace any leaking fuel injector(s).
Is the action complete?
ÐVerify repairÐ
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

6E±119
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Fuel System Diagnosis

 
StepNo Ye s Value(s) Action
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 the 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?
ÐVerify repairÐ
20Visually and physically inspect the fuel rail outlet
passages for a restriction.
Was a restriction found?
ÐVerify repairGo to Step 11
21Is the fuel pressure indicated by the fuel pressure
gauge above the specified value?
0 kPa (0 psi)Go to Step 22Go to Step 23
221. Command the fuel pump ªONº with the 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 ªONº with the 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?
ÐGo to Step 7
Go to Fuel
System
Electrical Test
Chart

6E±120
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Exhaust Gas Recirculation (EGR) System Check
060R200050
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±121
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Exhaust Gas Recirculation (EGR) System Check

StepActionValue(s)Ye sNo
1Check the EGR valve for looseness.
Is the EGR valve Loose?
ÐGo to Step 2Go to Step 3
2Tighten the EGR valve.
Is the action complete?
ÐVerify repairÐ
31. Place the transmission selector in Park or Neutral.
2. Start the engine and idle until warm.
3. Using a Tech 2, command EGR ª50% ONº.
(Refer to the Miscellaneous Test.)
Does the engine idle rough and lose RPMs?
Ð
EGR system
working
properly. No
problem
found.
Go to Step 4
41. Engine ªOFFº.
2. Ignition ªONº.
3. Using a test light to ground, check the EGR harness
between the EGR valve and the ignition feed.
Does the test light illuminate?
ÐGo to Step 6Go to Step 5
5Repair the EGR harness ignition feed.
Was the problem corrected?
ÐVerify repairGo to Step 6
61. Remove the EGR valve.
2. Visually and physically inspect the EGR valve
pintle, valve passages and adapter for excessive
deposits, obstructions or any restrictions.
Does the EGR valve have excessive deposits,
obstructions or any restrictions?
ÐGo to Step 7Go to Step 8
7Clean or replace EGR system components as
necessary.
Was the problem corrected?
ÐVerify repairGo to Step 8
81. Ground the EGR valve metal case to battery (±).
2. Using a Tech 2, command EGR ªONº and observe
the EGR valve pintle for movement.
Does the EGR valve pintle move according to
command?
ÐGo to Step 9
Go to DTC
P1406 chart
91. Remove the EGR inlet and outlet pipes from the
intake and exhaust manifolds.
2. Visually and physically inspect manifold EGR ports
and EGR inlet and outlet pipes for blockage or
restriction caused by excessive deposits or other
damage.
Do the manifold EGR ports or inlet and outlet pipes
have excessive deposits, obstructions, or any
restrictions?
ÐGo to Step 10
EGR system
working
properly. No
problem
found.
10Clean or replace EGR system components as
necessary.
Is the action complete?
ÐVerify repairÐ

6E±122
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Manifold Absolute Pressure (MAP) Output Check
060R200051
Circuit Description
The manifold absolute pressure (MAP) sensor measures
the changes in the intake MAP which result from engine
load (intake manifold vacuum) and engine speed
changes; and converts these into a voltage output. The
powertrain control module (PCM) sends a 5-volt
reference voltage to the MAP sensor. As the MAP
changes, the output voltage of the sensor also changes.
By monitoring the sensor output voltage, the PCM knows
the MAP. A lower pressure (low voltage) output voltage
will be about 1-2 volts at idle. Higher pressure (high
voltage) output voltage will be about 4-4.8 volts at wide
open throttle. The MAP sensor is also used, under certain
conditions, to measure barometric pressure, allowing the
PCM to make adjustments for different altitudes. The
PCM uses the MAP sensor to diagnose proper operation
of the EGR system, in addition to other functions.
Test Description
IMPORTANT:Be sure to used the same diagnostic test
equipment for all measurements.
The number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Applying 34 kPa (10 inch Hg) vacuum to the MAP
sensor should cause the voltage to be 1.5-2.1 volts
less than the voltage at step 1. Upon applying
vacuum to the sensor, the change in voltage should
be instantaneous. A slow voltage change indicates
a faulty sensor.
3. Check the vacuum hose to the sensor for leaking or
restriction, Be sure that no other vacuum devices
are connected to the MAP hose.
IMPORTANT:Make sure the electrical connector
remains securely fastened.
4. Disconnect the sensor from the bracket. Twist the
sensor with your hand to check for an intermittent
connection. Output changes greater than 0.10 volt
indicate a bad sensor.

6E±123
6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Manifold Absolute Pressure (MAP) Output Check

StepActionValue(s)Ye sNo
11. Turn the ignition ªOFFº and leave it ªOFFº for 15
seconds.
2. Ignition ªONº. Don't crank engine.
3. The Tech 2 should indicate a manifold absolute
pressure (MAP) sensor voltage.
4. Compare this scan reading to scan reading of a
known good vehicle obtained using the exact same
procedure as in Steps 1-4.
Is the voltage reading the same +/±0.40 volt?
ÐGo to Step 2Go to Step 5
21. Disconnect the vacuum hose at the MAP sensor
and plug the hose.
2. Connect a hand vacuum pump to the MAP sensor.
3. Start the engine.
4. Apply 34 kPa (10 in.Hg) of vacuum and note the
voltage change.
Is the voltage change 1.5-2.1 volts less than Step 1?
ÐGo to Step 3Go to Step 4
3Check the sensor cover for leakage or restriction.
Does the hose supply vacuum to the MAP sensor only?
ÐGo to Step 5Go to Step 4
4Repair the hose blockage.
Is the action complete?
ÐVerify repairÐ
5Check the sensor connection.
Is the sensor connection good?
ÐGo to Step 6Go to Step 7
6Refer to On-Vehicle Service, MAP Sensor.
Is the action complete?ÐVerify repairÐ
7Repair the poor connection.
Is the action complete?
ÐVerify repairÐ