Isuzu N 2008 Series Workshop Manual page 343

1A-340 Engine Control System (4JJ1)
Checks
Air Intake System Checks
Exhaust System Checks
Engine Mechanical 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 worn or damaged turbocharger turbine wheel, shaft or compressor wheel. Refer
to Turbocharger Assembly in Section 1J Engine Induction.
• Turbocharger wastegate valve operation. Refer to Turbocharger Assembly in
Section 1J Engine Induction. (Except Euro 4 specification)
• Turbocharger nozzle control actuator operation. Refer to Turbocharger Assembly in
Section 1J Engine Induction. (Euro 4 specification)
Inspect the exhaust system for a possible restriction. Refer to Exhaust System in
Section 1G Engine Exhaust.
Inspect the engine mechanical for the following conditions. Refer to Section 1B Engine
Mechanical.
• Poor cylinder compression.
• Improper valve gap.
• Broken or weak valve springs.
• Worn camshaft lobes.
Action