ISUZU KB P190 2007 Workshop Repair Manual

Engine Control System (4JH1) 6E-257
Checks Action
Electrical Connections or W iring Poor electrical connections, terminal tension or wiring problems cause most intermittent. To perform the following inspections:
• Inspect for poor mating of the connector halves, or terminals improperly seated in the
connector body.
• Inspect for improperly formed or damaged terminals. Test for poor terminal tension.
• Inspect for poor terminal to wire connections including terminals crimped over
insulation. This requires removing the terminal from the connector body.
• Inspect for corrosion/water intrusion. Pierced or damaged insulation can allow
moisture to enter the wiring. The conductor can corrode inside the insulation, with
little visible evidence. Look for swollen and stiff sections of wire in the suspect
circuits.
• Inspect for wires that are broken inside the insulation.
• Inspect the harness for pinched, cut or rubbed through wiring.
• Ensure that the wiring does not come in contact with hot exhaust components.
Control Module Power and Grounds
Component Power and Grounds Poor power or ground connections can cause widely varying symptoms.
• Test all control module power supply circuits. Many vehicles have multiple circuits
supplying power to the control module. Other components in the system may have
separate power supply circuits that may also need to be tested. Inspect connections
at the module/component connectors, fuses, and any intermediate connections
between the power source and the module/component. A test lamp or a DMM may
indicate that voltage is present, but neither tests the ability of the circuit to carry
sufficient current. Ensure that the circuit can carry the current necessary to operate
the component.
• Test all control module ground and system ground circuits. The control module may
have multiple ground circuits. Other components in the system may have separate
grounds that may also need to be tested. Inspect grounds for clean and tight
connections at the grounding point. Inspect the connections at the component and in
splice packs, where applicable. Ensure that the circuit can carry the current
necessary to operate the component.
Temperature Sensitivity • An intermittent condition may occur when a component/connection reaches normal
operating temperature. The condition may occur only when the
component/connection is cold, or only when the component/connection is hot.
• If the intermittent is related to heat, review the data for a relationship with the
following: - High ambient temperatures
- Under hood/engine generated heat
- Circuit generated heat due to a poor connection, or high electrical load
- Higher than normal load conditions, towing, etc.
• If the intermittent is related to cold, review the data for the following:
- Low ambient temperatures–In extremely low temperatures, ice may form in a connection or component. Test for water intrusion.
- The condition only occurs on a cold start.
- The condition goes away when the vehicle warms up.
• Information from the customer may help to determine if the trouble follows a pattern
that is temperature related.

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ISUZU KB P190 2007

6E-258 Engine Control System (4JH1)
Checks Action
Electromagnetic Interference (EMI)
and Electrical Noise Some electrical components/circuits are sensitive to EMI or other types of electrical
noise. Inspect for the following conditions:
• A misrouted harness that is too close to high voltage/high current devices such as
injection components, motors, generator etc. These components may induce
electrical noise on a circuit that could interfere with normal circuit operation.
• Electrical system interference caused by a malfunctioning relay, or the engine control
module (ECM) driven solenoid or switch. These conditions can cause a sharp
electrical surge. Normally, the problem will occur when the malfunctioning
component is operating.
• Improper installation of non-factory or aftermarket add on accessories such as lights,
2-way radios, amplifiers, electric motors, remote starters, alarm systems, cell
phones, etc. These accessories may lead to an emission related failure while in use,
but do not fail when the accessories are not in use.
• Test for an open diode across the A/C compressor clutch and for other open diodes.
Some relays may contain a clamping diode.
• Test the generator for a bad rectifier bridge that may be allowing AC noise into the
electrical system.
Incorrect ECM Programming • There are only a few situations where reprogramming a ECM is appropriate:
Important:
DO NOT reprogram the ECM with the SAME software/calibration files that are already
present in the ECM. This is not an effective repair for any type of driveability problem. - A ECM from another vehicle is installed.
- Revised software/calibration files have been released for this vehicle.
• Verify that the ECM contains the correct software/calibration. If incorrect
programming is found, reprogram the ECM with the most current
software/calibration.
Duplicating Failure Conditions • If none of the previous tests are successful, attempt to duplicate and/or capture the
failure conditions.
• An alternate method is to drive the vehicle with the DMM connected to a suspected
circuit. An abnormal reading on the DMM when the problem occurs, may help you
locate the problem.
scan tool Snapshot The scan tool can be set up to take a Snapshot of the parameters available via serial
data. The Snapshot function records live data over a period of time. The recorded data
can be played back and analyzed. The scan tool can also graph parameters singly or
in combinations of parameters for comparison. The Snapshot can be triggered
manually at the time the symptom is noticed, or set up in advance to trigger when a
DTC sets.
An abnormal value captured in the recorded data may point to a system or component
that needs to be investigated further.
Refer to the scan tool user instructions for more information on the Snapshot function.


Hard Start
Checks Action
DEFINITION:The engine cranks OK, but does not start for a long time. The engine does eventually run, or may start but
immediately dies.
Preliminary Checks •
Diagnostic System Check - Engine Controls.
• Ensure the driver is using the correct starting procedure.
• Inspect the engine control module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect that the harness connectors are correctly connected.
• Inspect the fuel type and quality.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-259
Checks Action
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to compare the Engine Coolant Temperature (ECT) with the Intake
Air Temperature (IAT) and Fuel Temperature (FT) on a cold engine condition. If the
difference among temperature reading is more than 5°C (9°F) on a cold engine,
check for high resistance on the low reference circuit and signal circuit or for a
skewed sensor.
Notice: The mass air flow (MAF) sensor is heated and as a result the IAT sensor may
indicate a higher than normal intake air temperature if the ignition switch is being ON.
FT sensor is internal to the PCU and it is part of the fuel injection pump assembly.
• Inspect the crankshaft position (CKP) sensor is tight and the flywheel circumference
is not damaged.
Fuel System Checks Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Inspect for water contamination in the fuel.
• Inspect for external fuel leaks or fuel leakage into the engine oil.
• Inspect the fuel lines between the fuel tank and fuel injection pump for tightness and
all fuel hoses for cuts, cracks and for the use of proper clamps.
Notice: The fuel system from the fuel tank(s) to the fuel injection pump is under a
slight vacuum with the engine running. As a result, air can enter the fuel system if
these connections are not tight. Air in the fuel system will cause fuel injection pump
internal pressure fluctuations especially at high engine speed and load.
• Inspect for air in the fuel system.
Notice: If many air bubbles appear in the fuel, check the fuel system line connections
between the fuel tank and the fuel injection pump for tightness and all fuel hoses for
cuts, cracks and for the use of proper clamps.
a. Remove the fuel hose that connects to the fuel injection pump suction side.
b. Substitute a clear hose.
Notice: A hose must be cleaned.
c. Connect the clear hose to the fuel injection pump.
d. Bleed the fuel system.
e. Let the engine run at idle for at least 2 minutes.
f. Accelerator the engine between idle and W .O.T. (accelerator pedal full travel) many times while observing the clear hose.
• Inspect the fuel tank vent hose for a plugged or kinked.
• Inspect inside the fuel tank for any foreign material that may be getting drawn into
the fuel line pickup causing a blocked condition. Draw fuel from the fuel tank at the
fuel line (as close to the fuel tank as possible) going to the fuel pickup tube to verify a
clean stream of fuel comes out (use the hand-held vacuum pump 5-8840-0279-0/J-
23738-A with a clear hose or equivalent). This will ensure the fuel pickup tube is not
cracked drawing air into the fuel line.
• Inspect the fuel injection pump operation.
Notice: The fuel injection pump must be timed to the engine.
• Inspect the eye bolt for any type of restriction or collapsed gauze filter.
Notice: If any type of restriction found, check for a condition that causes contaminated
fuel, such as the customer is using an aftermarket fuel filter or extended maintenance
interval. Also inspect fuel waxing or icing that is caused by an incorrect fuel type used
in winter season or water intrusion in the fuel system.
• Inspect the fuel injection nozzle(s) for proper splay condition or operating pressure.
Notice: Only first stage of operating pressure can be checked.
Air Intake System Checks Inspect the air intake system for the following conditions.
• Inspect the air cleaner and air intake ducts for a restriction, holes, or leaks.
• Inspect for a restriction in the turbocharger inlet duct.
• Inspect for a restriction or deposit in the intake throttle bore.
• Inspect for a restriction or leak in the intake manifold.
Exhaust System Checks Inspect the exhaust system for a possible restriction. Refer to the Exhaust System
section.
• Inspect for a restriction in the catalytic converter or exhaust pipes.

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ISUZU KB P190 2007

6E-260 Engine Control System (4JH1)
Checks Action
Engine Mechanical Checks Inspect the engine mechanical for the following conditions. Refer to the Engine
Mechanical section.
• Inspect for poor cylinder compression. Proper compression is more than 2100 kPa
(309 psi).
• Improper mechanical timing (timing gear)
• Improper valve gap
• Broken or weak valve springs
• W orn camshaft lobes
Electrical System Checks Inspect the engine electrical for the following conditions. Refer to the Engine Electrical
section.
• Inspect the glow plug control (preheating) system operation.
• Inspect for slow cranking speed.
• Inspect for weakened batteries.


Rough, Unstable, or Incorrect Idle And Stalling
Checks Action
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.
Preliminary Checks • Diagnostic System Check - Engine Controls.
• Remove the air cleaner and check for dirt, or for air ducts being plugged or restricted.
Replace as necessary.
• Inspect the Engine Control Module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect that the harness connectors are correctly connected.
• Inspect the fuel type and quality.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool Data
List in this section.
• Use the scan tool to compare the Engine Coolant Temperature (ECT) with the Intake Air
Temperature (IAT) and Fuel Temperature (FT) on a cold engine condition. If the
difference among temperature reading is more than 5°C (9°F) on a cold engine, check for
high resistance on the low reference circuit and signal circuit or for a skewed sensor.
Notice: The mass air flow (MAF) sensor is heated and as a result the IAT sensor may
indicate a higher than normal intake air temperature if the ignition switch is being ON. FT
sensor is internal to the PCU and it is part of the fuel injection pump assembly.
• Use the scan tool to compare the MAF Sensor parameter with the Desired MAF
parameter. Start the engine and warm up (allow engine coolant temperature to reach at
least 60°C [140°F]). The MAF Sensor parameter must follow the Desired MAF parameter
within 100 mg/strk. If not, inspect the air intake system, EGR system components and
contaminated, skewed or slow MAF sensor.
• Inspect the crankshaft position (CKP) sensor is tight and the flywheel circumference is
not damaged.

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-261
Checks Action
Fuel System Checks Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Inspect for water contamination in the fuel.
• Inspect for external fuel leaks or fuel leakage into the engine oil.
• Inspect the fuel lines between the fuel tank and fuel injection pump for tightness and all
fuel hoses for cuts, cracks and for the use of proper clamps.
Notice: The fuel system from the fuel tank(s) to the fuel injection pump is under a slight
vacuum with the engine running. As a result, air can enter the fuel system if these
connections are not tight. Air in the fuel system will cause fuel injection pump internal
pressure fluctuations especially at high engine speed and load.
• Inspect for air in the fuel system.
Notice: If many air bubbles appear in the fuel, check the fuel system line connections
between the fuel tank and the fuel injection pump for tightness and all fuel hoses for cuts,
cracks and for the use of proper clamps.
a. Remove the fuel hose that connects to the fuel injection pump suction side.
b. Substitute a clear hose.
Notice: A hose must be cleaned.
d. Connect the clear hose to the fuel injection pump.
c. Bleed the fuel system.
e. Let the engine run at idle for at least 2 minutes.
f. Accelerator the engine between idle and W .O.T. (accelerator pedal full travel) many times while observing the clear hose.
• Inspect the fuel tank vent hose for a plugged or kinked.
• Inspect inside the fuel tank for any foreign material that may be getting drawn into the
fuel line pickup causing a blocked condition. Draw fuel from the fuel tank at the fuel line
(as close to the fuel tank as possible) going to the fuel pickup tube to verify a clean
stream of fuel comes out (use the hand-held vacuum pump 5-8840-0279-0/J-23738-A
with a clear hose or equivalent). This will ensure the fuel pickup tube is not cracked
drawing air into the fuel line.
• Inspect the fuel injection pump operation.
Notice: The fuel injection pump must be timed to the engine.
• Inspect the eye bolt for any type of restriction or collapsed gauze filter.
Notice: If any type of restriction found, check for a condition that causes contaminated
fuel, such as the customer is using an aftermarket fuel filter or extended maintenance
interval. Also inspect fuel waxing or icing that is caused by an incorrect fuel type used in
winter season or water intrusion in the fuel system.
• Inspect the fuel injection nozzle(s) for proper splay condition or operating pressure.
Notice: Only first stage of operating pressure can be checked.
Air Intake System Checks Inspect the air intake system for the following conditions.
• Inspect the air cleaner and air intake ducts for a restriction, holes, or leaks.
• Inspect for a restriction in the turbocharger inlet duct.
• Inspect for a restriction or deposit in the intake throttle bore.
• Inspect for a restriction or leak in the intake manifold.
• Inspect for a restriction or damage at MAF sensor.
Exhaust System Checks Inspect the exhaust system for a possible restriction. Refer to the Exhaust System section.
• Inspect for a restriction in the catalytic converter or exhaust pipes.
Engine Mechanical Checks Inspect the engine mechanical for the following conditions. Refer to the Engine Mechanical
section.
• Inspect for poor cylinder compression. Proper compression is more than 2100 kPa (309
psi).
• Improper mechanical timing
• Improper valve gap
• Broken or weak valve springs
• W orn camshaft lobes
• Inspect for incorrect basic engine parts.

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ISUZU KB P190 2007

6E-262 Engine Control System (4JH1)
Checks Action
Additional Checks •
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss
condition. The scan tool can usually detect EMI by monitoring the engine speed. A
sudden increase in speed with little change in actual engine speed change indicates that
EMI is present. If a problem exists, check routing of high voltage components, such as
fuel injection solenoid valve wiring, near the sensor circuits.
• Inspect for faulty engine mounts.
• Inspect faulty crank pulley.
• Inspect faulty generator & A/C compressor.
• Inspect the generator output voltage. Repair if less than 9 volts or more than 16 volts.
• Inspect the EGR system operating correctly.
• Inspect the A/C operation.


Cut Out, Misses
Checks Action
DEFINITION:A constant jerking that follows the engine speed, usually more pronounced as the engine load increase. The
exhaust has a steady spitting sound at idle, low speed, or hard acceleration for the fuel starvation that can cause the engine to
cut-out.
Preliminary Check • Diagnostic System Check - Engine Controls.
• Inspect that the harness connectors are correctly connected.
• Inspect the engine control module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to observe the Accelerator Pedal Position. Accelerator Pedal
Position indicating angle parameter should change linearly from 0% to 100%
according to the accelerator pedal operation.
• Inspect the crankshaft position (CKP) sensor is tight and the flywheel circumference
is not damaged.

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-263
Checks Action
Fuel System Checks Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Inspect for water contamination in the fuel.
• Inspect for external fuel leaks or fuel leakage into the engine oil.
• Inspect the fuel lines between the fuel tank and fuel injection pump for tightness and
all fuel hoses for cuts, cracks and for the use of proper clamps.
Notice: The fuel system from the fuel tank(s) to the fuel injection pump is under a
slight vacuum with the engine running. As a result, air can enter the fuel system if
these connections are not tight. Air in the fuel system will cause fuel injection pump
internal pressure fluctuations especially at high engine speed and load.
• Inspect for air in the fuel system.
Notice: If many air bubbles appear in the fuel, check the fuel system line connections
between the fuel tank and the fuel injection pump for tightness and all fuel hoses for
cuts, cracks and for the use of proper clamps.
a. Remove the fuel hose that connects to the fuel injection pump suction side.
b. Substitute a clear hose.
Notice: A hose must be cleaned.
c. Connect the clear hose to the fuel injection pump.
d. Bleed the fuel system.
e. Let the engine run at idle for at least 2 minutes.
f. Accelerator the engine between idle and W .O.T. (accelerator pedal full travel) many times while observing the clear hose.
• Inspect the fuel tank vent hose for a plugged or kinked.
• Inspect inside the fuel tank for any foreign material that may be getting drawn into
the fuel line pickup causing a blocked condition. Draw fuel from the fuel tank at the
fuel line (as close to the fuel tank as possible) going to the fuel pickup tube to verify a
clean stream of fuel comes out (use the hand-held vacuum pump 5-8840-0279-0/J-
23738-A with a clear hose or equivalent). This will ensure the fuel pickup tube is not
cracked drawing air into the fuel line.
• Inspect the fuel injection pump operation.
Notice: The fuel injection pump must be timed to the engine.
Inspect the eye bolt for any type of restriction or collapsed gauze filter.
Notice: If any type of restriction found, check for a condition that causes contaminated
fuel, such as the customer is using an aftermarket fuel filter or extended maintenance
interval. Also inspect fuel waxing or icing that is caused by an incorrect fuel type used
in winter season or water intrusion in the fuel system.
Air Intake System Checks Inspect the air intake system for the following conditions.
• Inspect the air cleaner and air intake ducts for a restriction, holes, or leaks.
• Inspect for a restriction in the turbocharger inlet duct.
• Inspect for a restriction or deposit in the intake throttle bore.
• Inspect for a restriction or leak in the intake manifold.
• Inspect for a restriction or damage at mass air flow (MAF) sensor.
Additional Checks •
Inspect the generator output voltage. Repair if less than 9 volts or more than 16
volts.
• Electromagnetic interference (EMI) on the reference circuit can cause an engine
miss condition. The scan tool can usually detect EMI by monitoring the engine
speed. A sudden increase in speed with little change in actual engine speed change
indicates that EMI is present. If a problem exists, check routing of high voltage
components, such as fuel injection solenoid wiring, near the sensor circuits.


Surges/Chuggles
Checks Action
DIFINITION:The engine has a power variation under a steady throttle or cruise. The vehicle seems to speed up and slow down
with no change in the accelerator pedal.

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ISUZU KB P190 2007

6E-264 Engine Control System (4JH1)
Checks Action
Preliminary Checks • Diagnostic System Check - Engine Controls.
• Ensure the driver understands the torque converter clutch (TCC) operation.
• Ensure the driver understands the A/C compressor operation.
• Use the scan tool in order to make sure the Vehicle Speed parameter reading
matches the vehicle speedometer.
• Inspect the engine control module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect that the harness connectors are correctly connected.
• Inspect the fuel type and quality.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to compare the Mass Air Flow (MAF) Sensor parameter with the
Desired MAF parameter. Start the engine and warm up (allow engine coolant
temperature to reach at least 60°C [140°F]). The MAF Sensor parameter must follow
the Desired MAF parameter within 100 mg/strk. If not, inspect the air intake system,
EGR system components and contaminated, skewed or slow MAF sensor.
• Use the scan tool to observe the Accelerator Pedal Position. Accelerator Pedal
Position parameter should change linearly from 0% to 100% according to the
accelerator pedal operation. Also inspect the Accelerator Pedal Position indicating
angle when the accelerator pedal is steady. If the indicating angle fluctuates, check
for an intermittent open, high resistance in the circuits or for a skewed sensor.
• Inspect the crankshaft position (CKP) sensor is tight and the flywheel circumference
is not damaged.

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-265
Checks Action
Fuel System Checks Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Inspect for water contamination in the fuel.
• Inspect for external fuel leaks or fuel leakage into the engine oil.
• Inspect the fuel lines between the fuel tank and fuel injection pump for tightness and
all fuel hoses for cuts, cracks and for the use of proper clamps.
Notice: The fuel system from the fuel tank(s) to the fuel injection pump is under a
slight vacuum with the engine running. As a result, air can enter the fuel system if
these connections are not tight. Air in the fuel system will cause fuel injection pump
internal pressure fluctuations especially at high engine speed and load.
• Inspect for air in the fuel system.
Notice: If many air bubbles appear in the fuel, check the fuel system line connections
between the fuel tank and the fuel injection pump for tightness and all fuel hoses for
cuts, cracks and for the use of proper clamps.
a. Remove the fuel hose that connects to the fuel injection pump suction side.
b. Substitute a clear hose.
Notice: A hose must be cleaned.
c. Connect the clear hose to the fuel injection pump.
d. Bleed the fuel system.
e. Let the engine run at idle for at least 2 minutes.
f. Accelerator the engine between idle and W .O.T. (accelerator pedal full travel) many times while observing the clear hose.
• Inspect the fuel tank vent hose for a plugged or kinked.
• Inspect inside the fuel tank for any foreign material that may be getting drawn into
the fuel line pickup causing a blocked condition. Draw fuel from the fuel tank at the
fuel line (as close to the fuel tank as possible) going to the fuel pickup tube to verify a
clean stream of fuel comes out (use the hand-held vacuum pump 5-8840-0279-0/J-
23738-A with a clear hose or equivalent). This will ensure the fuel pickup tube is not
cracked drawing air into the fuel line.
• Inspect the fuel injection pump operation.
Notice: The fuel injection pump must be timed to the engine.
• Inspect the eye bolt for any type of restriction or collapsed gauze filter.
Notice: If any type of restriction found, check for a condition that causes contaminated
fuel, such as the customer is using an aftermarket fuel filter or extended maintenance
interval. Also inspect fuel waxing or icing that is caused by an incorrect fuel type used
in winter season or water intrusion in the fuel system.
• Inspect the fuel injection nozzle(s) for proper splay condition or operating pressure.
Notice: Only first stage of operating pressure can be checked.
• Inspect the timing device operating correctly. Observe the Actual Injection Timing
parameter with the scan tool while running the engine. The Actual Injection Timing
parameter must follow the Desired Injection Timing within 2°CA on each engine
speed. Engine idle > around 2000 RPM> around 3000 RPM. If not, inspect the fuel
system restriction, air in the fuel or fuel injection pump operation.
Air Intake System Checks Inspect the air intake system for the following conditions.
• Inspect the air cleaner and air intake ducts for a restriction, holes, or leaks.
• Inspect for a restriction in the turbocharger inlet duct.
• Inspect for a restriction or deposit in the intake throttle bore.
• Inspect for a restriction or leak in the intake manifold.
• Inspect for a restriction or damage at MAF sensor.
Additional Checks •
Inspect the generator output voltage. Repair if less than 9 volts or more than 16
volts.
• Inspect the EGR system operating correctly.
• Inspect the A/C operation.
• Inspect the torque converter clutch (TCC) operation. (A/T only)



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6E-266 Engine Control System (4JH1)
Lack of Power, Sluggishness, Sponginess
Checks Action
DEFINITION:The engine delivers less than expected power. There is little or no increase in speed when partially applying the
accelerator pedal.
Preliminary Checks • Diagnostic System Check - Engine Controls.
• Compare the vehicle with a similar unit. Ensure the vehicle has an actual problem.
• Remove the air cleaner and check for dirt, or for air ducts being plugged or
restricted. Replace as necessary.
• Have the tire sizes changed?
• Are excessively heavy loads being carried?
• Inspect for clutch slip.
• Inspect brake drag.
• Inspect for a proper transmission shift pattern and down shift operation (A/T only).
• Inspect the fuel quality (cetane index).
• Inspect the engine oil level and quality.
• Use the scan tool in order to make sure the Vehicle Speed parameter reading
matches the vehicle speedometer.
• Inspect the engine control module (ECM) and fuel injection pump control unit (PCU)
grounds for being clean, tight, and in their proper locations.
• Inspect the scan tool Data List in this section.
• Inspect the Service Bulletins for ECM software updates.
Sensor Checks Inspect the engine control sensors for the following conditions. Refer to the scan tool
Data List in this section.
• Use the scan tool to compare the Engine Coolant Temperature (ECT) with the Intake
Air Temperature (IAT) and Fuel Temperature (FT) on a cold engine condition. If the
difference among temperature reading is more than 5°C (9°F) on a cold engine,
check for high resistance on the low reference circuit and signal circuit or for a
skewed sensor.
Notice: The mass air flow (MAF) sensor is heated and as a result the IAT sensor may
indicate a higher than normal intake air temperature if the ignition switch is being
ON. FT sensor is internal to the PCU and it is part of the fuel injection pump
assembly.
• Use the scan tool to compare the MAF Sensor parameter with the Desired MAF
parameter. Start the engine and warm up (allow engine coolant temperature to reach
at least 60°C [140°F]). The MAF Sensor parameter must follow the Desired MAF
parameter within 100 mg/strk. If not, inspect the air intake system, EGR system
components and contaminated, skewed or slow MAF sensor.
• Use the scan tool to observe the Accelerator Pedal Position Accelerator Pedal
Position. Accelerator Pedal Position parameter should change linearly from 0% to
100% according to the accelerator pedal operation.

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ISUZU KB P190 2007