Isuzu 2008MY N Series, Руководство по ремонту

Страница: 365 / 404

1A-362 Engine Control System (4HK1)
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
(Smoother only).
• 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 Fuel System in
Section 1D Engine Fuel.
• Fuel type and quality.
• Check fuel leak.
Cooling System Checks Inspect the cooling system for the following conditions. Refer to Cooling
System in Section 1C Engin Cooling.
• Engine coolant level.
• Engine thermostat for always being open or for the wrong heat range.
• Engine cooling fan for always being ON.
LG4HKED-WE-0871.book 362 ページ ２００７年１１月２９日 木曜日 午後６時２９分