Detonation/Spark Knock. Isuzu Ascender

For 1990-2009 cars only

Makes 🢒 Isuzu 🢒 2004 🢒 Ascender - 4WD 🢒 Engine 🢒 Engine Electrical 🢒 Detonation/Spark Knock

Inspections

Action

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

Preliminary

•	Refer to Symptoms - Engine Controls .

•	Verify the customer's concern.

Cooling System

•	Inspect for a low engine coolant level.

•	Inspect for a correct coolant mixture.

•	Inspect for the proper tension on the drive belts. Refer to Drive Belt Tensioner Diagnosis .

•	Inspect for restricted air flow through the radiator, or restricted coolant flow.

•	Inspect for a faulty thermostat. Refer to Thermostat Diagnosis .

Sensor/System

Inspect for an engine coolant temperature (ECT) sensor that has a shift in value. Refer to Temperature Versus Resistance .

Fuel System

•	Drive the vehicle at the speed of the complaint. Monitoring the fuel trim will help identify the problem.

•	If the system is lean, the long term fuel trim will be more than 150.

•	Test the fuel pressure. Refer to Fuel System Diagnosis .

•	Inspect for a poor fuel quality and a proper octane rating.

•	If the fuel trim readings are normal and there are no engine mechanical concerns, then fill the fuel tank with a known good fuel and re-evaluate the vehicle performance.

Ignition System

•	Inspect the spark plugs for their proper heat range and gap.

•	Inspect the knock sensor (KS) system operation.

•	Inspect the ignition timing.

Engine Mechanical

•	Inspect for carbon build up. Remove the carbon with a top engine cleaner. Follow the instructions on the can.

•	Test the combustion chamber pressure by performing a compression test. Refer to Engine Compression Test .

Additional

•	Inspect the torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis .

•	Search for Service Bulletins for calibration updates.