1A-338 Engine Control System (4JJ1)
Abnormal Combustion Noise
Checks Action
Definition:
A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with the throttle
opening.
Preliminary Checks • Diagnostic System Check - Engine Controls.
• Ensure the vehicle has an actual problem.
• Inspect for smoke associated with the combustion noise.
• Inspect the fuel quality (cetane index).
• 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 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 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.
• Crankshaft position (CKP) sensor is tight and the sensor rotor is not damaged.
Fuel System Checks • If excessive smoke is present, check for a stuck open fuel injector. Inspect for fuel
leakage into the combustion chamber.
• Inspect the fuel injectors. Remove the injectors and visually inspect.
• Perform the Cylinder Balance Test with a scan tool.
• Perform the Injector Forced Drive with a scan tool.
• Observe the Fuel Compensation for each cylinder at idle on the scan tool.
Engine Mechanical Checks Inspect the engine mechanical for the following conditions. Refer to Section 1B Engine
Mechanical.
• Poor cylinder compression.
• Incorrect basic engine parts such as camshaft, cylinder head, pistons, etc.
• Inspect for any excessive oil entering combustion chamber.
Additional Checks • Inspect other possible causes that can make similar noise such as loose component
parts, bracket, mount and weak clutch damper spring.
LG4JJED-WE-0871.book 338 ページ ２００８年４月４日 金曜日 午前９時６分
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