Isuzu 2008MY N Series Workshop Manual page 370

Checks
Air Intake System Checks
Exhaust System Checks
Engine Mechanical Checks
Electrical 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.
Oil leak from turbocharger. Refer to Turbocharger Assembly in Section 1J
Induction.
If an excessive white smoke is present while DPD filter regeneration process, a
deteriorated or damaged oxygen catalyst is suspected.
Inspect the engine mechanical for the following conditions. Refer to the Section
1B Engine Mechanical.
• Poor cylinder compression.
• Improper mechanical timing (timing gear).
• Improper valve gap.
• Broken or weak valve springs.
• Worn camshaft lobes.
• Thermostat working (open stuck).
• Any excessive oil entering combustion chamber.
• Glow plug control (preheating) system operation. Refer to Glow Control
System Check in this section.
Engine Control System (4HK1)
Action
1A-367