Excessive Smoke (Black Smoke) - Isuzu 2008MY N Series Workshop Manual

1A-364 Engine Control System (4HK1)

Excessive Smoke (Black Smoke)

Checks
Definition:
Black smoke under load, idle or start up hot or cold.
Preliminary Check
Sensor Checks
Fuel System Checks
• 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.
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 ignition switch
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 Boost Pressure and Barometric Pressure (BARO) with ignition
ON and engine OFF. Both parameters should be within the 7.0 kPa (1.0 psi)
each other.
Inspect the fuel system for the following conditions. Refer to Fuel System in
Section 1D Engine Fuel.
• 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.
Action