Isuzu KB P190. Manual - part 490
ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-343
Excessive Smoke (Black Smoke)
Checks
Action
Definition:
Black smoke under load, idle or start up hot or cold.
Preliminary Check
• Ensure the vehicle has an actual problem.
• Inspect the ECM grounds for being clean, tight, and in their proper locations.
• Remove the air cleaner and check for dirt, or for air ducts being plugged or
restricted. Replace as necessary.
• Inspect the fuel quality (cetane index).
• Inspect the engine oil level and quality.
• 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 MAF parameter for a skewed or slow MAF sensor.
• 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.
• Observe the Barometric Pressure (BARO) parameter. The BARO parameter should
indicate near surrounding barometric pressure. Refer to Altitude vs. Barometric
Pressure. (Standard output)
• Observe the Boost Pressure and BARO with ignition ON and engine OFF. Both
parameters should be within the 7.0 kPa (1.0 psi) each other. (High output)
Fuel System Checks
Inspect the fuel system for the following conditions. Refer to the Fuel System section.
• Fuel injectors. Remove the injectors and visually inspect.
• Perform the Cylinder Balance Test with a scan tool.
• Perform the Pilot Injection Control 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.
• A worn or damaged turbocharger turbine wheel, shaft or compressor wheel. Refer
to turbocharger inspection in the Engine Mechanical section.
Exhaust System Checks
Inspect the exhaust system for a possible restriction. Refer to the Exhaust System
section.