Detonation/Spark Knock. Buick LeSabre 2005

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2005 🢒 LeSabre 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Detonation/Spark Knock

Inspection/Tests

Action

DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

Preliminary Inspections

•	Perform the Diagnostic System Check - Vehicle in Vehicle DTC Information

•	Search for bulletins.

•	Inspect the powertrain control module (PCM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems.

•	If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicles minimum octane requirements. Road test the vehicle and re-evaluate the vehicles performance.

Fuel System

•	Test for low fuel pressure. Refer to Fuel System Diagnosis .

•	Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 .

Ignition System

Inspect the spark plugs for proper heat range and reach.

Engine Cooling System

Inspect for obvious overheating conditions:

•	Low engine coolant. Refer to Loss of Coolant in Engine Cooling.

•	Restricted air flow to radiator, or restricted water flow through radiator.

•	Inoperative electric cooling fan circuits. Refer to Cooling Fan Inoperative in Engine Cooling.

•	Correct coolant solution. Refer to Cooling System Draining and Filling in Engine Cooling.

Engine Mechanical

•	Excessive oil in combustion chamber--Leaking valve seals--Refer to Oil Consumption Diagnosis in Engine Mechanical - 3.8L.

•	Low cylinder compression--Refer to Engine Compression Test in Engine Mechanical - 3.8L.

•	Combustion chambers for excessive carbon buildup--Clean using top engine cleaner. Follow instructions on can.

•	For incorrect basic engine parts--Inspect the following:

Camshaft

-	Cylinder heads

-	Pistons, etc.

Additional Inspections

•	Test for proper exhaust gas recirculation (EGR) system operation. Refer to DTC P0401 .

•	Inspect the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive.

•	Test torque converter clutch (TCC) operation. TCC applying too soon can cause the engine to spark knock. Refer to Torque Converter Diagnosis in Automatic Transaxle - 4T65-E.

•	If scan tool readings are normal and there are no engine mechanical faults, fill the fuel tank with a known quality gasoline that has a minimum octane reading of 87 and re-evaluate vehicle performance.