Isuzu KB P190. Manual - part 489

 

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Isuzu KB P190. Manual - part 489

 

 

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-339

Fuel System Checks

Inspect the fuel system for the following conditions. Refer to Fuel System Check Chart
and appropriate procedure in the Fuel System section.

• Air in the fuel system.

• Water contamination in the fuel.

• Fuel waxing or icing.

• Fuel filter indicator lamp is continuously or frequently turned ON with engine run.

• External fuel leaks or high engine oil level.

• In-tank fuel pump operation. Refer to In-tank Fuel Pump System Check in this

section.

• Fuel leak off from the fuel pressure limiter valve and fuel injectors.

• Fuel lines between the fuel tank and fuel supply pump for being crushed, kinked,

tightness, cracks and plugged.

• A plugged fuel tank vent valve and hose.

• Inside the fuel tank for any foreign material that may be getting drawn into the fuel

line pickup causing a blocked condition.

• Fuel supply pump operation.

Notice: The fuel supply pump must be timed to the engine and adjustment value must
be learned to the ECM.

• Perform the Cylinder Balance Test with a scan tool.

• Perform the Injector Force Drive with a scan tool.

• Observe the Fuel Compensation for each cylinder at idle on the scan tool.

Air Intake System Checks

Inspect the air intake system for the following conditions.

• Air cleaner, air intake ducts and charge air cooler for a restriction, holes, or leaks.

• A restriction in the turbocharger inlet duct.

• Intake throttle valve for a stuck condition.

• A restriction or leak in the intake manifold.

• A restriction or damaged at MAF sensor.

• Perform the Swirl Control Solenoid Test with a scan tool. Inspect the diaphragm

valve operation when it commanded ON/ OFF.

• A worn or damaged turbocharger turbine wheel, shaft or compressor wheel. Refer

to turbocharger inspection in the Engine Mechanical section.

• Turbocharger wastegate valve operation. Refer to wastegate valve inspection in the

Engine Mechanical section. (Standard output)

• Turbocharger nozzle control actuator operation. Refer to Turbocharger Control

System Check in this section. (High output)

Exhaust System Checks

Inspect the exhaust system for a possible restriction. Refer to the Exhaust System
section.

Engine Mechanical Checks

Inspect the engine mechanical for the following conditions. Refer to the Engine
Mechanical section.

• Poor cylinder compression.

• Improper valve gap.

• Broken or weak valve springs.

• Worn camshaft lobes.

Additional Checks

• Inspect the EGR system operating correctly. Refer to EGR Control System Check in

this section.

• Inspect for an engine overheat condition. Refer to Engine Cooling section.

• Inspect the A/C operation.

• Inspect the torque converter clutch (TCC) operation. (A/T only)

Checks

Action

6E-340   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Abnormal Combustion Noise

Checks

Action

Definition:
A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with the throttle 
opening.

Preliminary Checks

• Diagnostic System Check - Engine Controls.

• Ensure the vehicle has an actual problem.

• Inspect for smoke associated with the combustion noise.

• Inspect the fuel quality (cetane index).

• Inspect the programmed fuel injector ID code for each cylinder.

• Inspect the Scan Tool Data List in this section.

• Inspect the Service Bulletin.

Sensor Checks

Inspect the engine control sensors for the following conditions. Refer to the Scan Tool
Data List in this section.

• Compare the Coolant Temperature with the Intake Air Temperature (IAT) and Fuel

Temperature (FT) parameters 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 in each circuit or for a skewed sensor.

Notice: The mass air flow (MAF) sensor is heated and as a result the IAT may indicate
a higher than normal intake air temperature if the ignition switch is being ON.

• Observe the Fuel Rail Pressure (FRP) Sensor parameter with the engine OFF. The

FRP Sensor should read 0.9 to 1.0 volt with the key ON and engine OFF after the
engine has stopped running for a minimum of 1 minute. If not, check for high
resistance in each circuit or for a skewed sensor.

• Observe the Fuel Rail Pressure and Desired Fuel Rail Pressure parameter between

idle and W.O.T. (accelerator pedal full travel) in Neutral. Fuel Rail Pressure
parameter should follow within 

± 5 MPa ( ± 725 psi) quick enough.

• Crankshaft position (CKP) sensor is tight and the sensor rotor is not damaged.

Fuel System Checks

• If excessive smoke is present, check for a stuck open fuel injector. Inspect for fuel

leakage into the combustion chamber.

• Inspect the fuel injectors. Remove the injectors and visually inspect.

• Perform the Cylinder Balance Test with a scan tool.

• Perform the Injector Force Drive with a scan tool.

• Observe the Fuel Compensation for each cylinder at idle on the scan tool.

Engine Mechanical Checks

Inspect the engine mechanical for the following conditions. Refer to the Engine
Mechanical section.

• Poor cylinder compression.

• Incorrect basic engine parts such as camshaft, cylinder head, pistons, etc..

• Inspect for any excessive oil entering combustion chamber.

Additional Checks

• Inspect other possible causes that can make similar noise such as loose component

parts, bracket, mount and weak clutch damper spring.

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-341

Poor Fuel Economy

Checks

Action

Definition:
Fuel economy, as measured by actual road tests and several tanks of fuel, is noticeably lower than expected. Also, the 
economy is noticeably lower than it was on this vehicle at one time, as previously shown by actual road tests.

Preliminary Checks

• Remove the air cleaner and check for dirt, or for air ducts being plugged or

restricted. Replace as necessary.

• Inspect the driving habits of the owner.

• Is the A/C ON full time, defroster mode ON?

• Are the tires at the correct pressure?

• Are the tire sizes changed?

• Are excessively heavy loads being carried?

• Is the acceleration too much, too often?

• Inspect for clutch slip.

• Inspect brake drag.

• Inspect dive belt tension.

• Inspect for a proper transmission shift pattern and down shift operation.

• Inspect the fuel quality (cetane index).

• Inspect the engine oil level and quality.

• Suggest to the owner to fill the fuel tank and recheck the fuel economy.

• Inspect the odometer is correctly operated.

• Inspect the Scan Tool Data List in this section.

• Inspect the Service Bulletin.

Sensor Checks

Inspect the engine control sensors for the following conditions. Refer to the Scan Tool
Data List in this section.

• Compare the Coolant Temperature with the Intake Air Temperature (IAT) and Fuel

Temperature (FT) parameters 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 in each circuit or for a skewed sensor.

Notice: The mass air flow (MAF) sensor is heated and as a result the IAT may indicate
a higher than normal intake air temperature if the ignition switch is being ON.

Fuel System Checks

Inspect the fuel system for the following conditions. Refer to the Fuel System section.

• Fuel type and quality.

• Check fuel leak.

Cooling System Checks

Inspect the cooling system for the following conditions. Refer to the Cooling System
Section.

• Engine coolant level.

• Engine thermostat for always being open or for the wrong heat range.

• Engine cooling fan for always being ON.

6E-342   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Air Intake System Checks

Inspect the air intake system for the following conditions.

• Air cleaner, air intake ducts and charge air cooler for a restriction, holes, or leaks.

• A restriction in the turbocharger inlet duct.

• Intake throttle valve for a stuck condition.

• A restriction or leak in the intake manifold.

• A restriction or damaged at MAF sensor.

• Perform the Swirl Control Solenoid Test with a scan tool. Inspect the diaphragm

valve operation when it commanded ON/ OFF.

• A worn or damaged turbocharger turbine wheel, shaft or compressor wheel. Refer

to turbocharger inspection in the Engine Mechanical section.

• Turbocharger wastegate valve operation. Refer to wastegate valve inspection in the

Engine Mechanical section. (Standard output)

• Turbocharger nozzle control actuator operation. Refer to Turbocharger Control

System Check in this section. (High output)

Exhaust System Checks

Inspect the exhaust system for a possible restriction. Refer to the Exhaust System
section.

Engine Mechanical Checks

Inspect the engine mechanical for the following conditions. Refer to the Engine
Mechanical section.

• Poor cylinder compression.

• Improper valve gap.

• Broken or weak valve springs.

• Worn camshaft lobes.

Checks

Action

 

 

 

 

 

 

 

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