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HOMESERVICE MANUALSCHEVROLET1998LUMINA V6-3.8L VIN KREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMKNOCK SENSORDESCRIPTION AND OPERATION
1998 Chevrolet Lumina V6-3.8L VIN K
Knock Sensor: Description and Operation
1998 Chevrolet Lumina V6-3.8L VIN KSECTION Description and Operation
DESCRIPTION
Varying octane levels in today's gasoline may cause detonation in some engines. Detonation is caused by an uncontrolled explosion (burn) in the combustion chamber. This uncontrolled explosion could produce a flame front opposite that of the normal flame front produced by the spark plug. The rattling sound normally associated with detonation is the result of two or more opposing pressures (flame fronts) colliding within the combustion chamber. Though light detonation is sometimes considered normal, heavy detonation could result in engine damage.
To control spark knock, a Knock Sensor (KS) system is used. This system is designed to retard spark timing to reduce spark knock in the engine. This allows the engine to use maximum spark advance to improve driveability and fuel economy.
COMPONENTS
The KS system has two major components:
^ KS module.
^ Knock sensor.
OPERATION
The knock sensor detects abnormal vibration (spark knocking) in the engine. The knock sensor is mounted in the engine block near the cylinders and produce an A/C signal under all engine operating conditions. The PCM contains integrated knock sensor (KS) diagnostic circuitry which uses the input signals from the knock sensors to detect engine detonation. This allows the PCM to retard Ignition Control (IC) spark timing based on the amplitude and frequency of the KS signal being received.
DIAGNOSIS
The PCM calculates an average voltage the knock sensor signal and takes instantaneous signal voltage readings. The PCM uses the instantaneous signal voltage reading to determine the state of the knock sensor circuitry. If the knock sensor system is operating normally, the PCM should monitor instantaneous KS signal voltage readings varying outside a voltage range above and below the calculated average voltage. The following DTCs are used to diagnose the knock sensor system:
^ If the PCM malfunctions in a manner which will not allow proper diagnosis of the KS circuits, DTC P0325 will set.
^ DTCs P0327 and P0332 are designed to diagnose the knock sensors, and related wiring, so problems encountered with the KS system should set a DTC. However, if no DTC was set but the KS system is suspect because detonation was the customer's complaint, use the table for P0327 and P0332 to diagnose the Detonation/Spark Knock Symptom. Testing and Inspection
Varying octane levels in today's gasoline may cause detonation in some engines. Detonation is caused by an uncontrolled explosion (burn) in the combustion chamber. This uncontrolled explosion could produce a flame front opposite that of the normal flame front produced by the spark plug. The rattling sound normally associated with detonation is the result of two or more opposing pressures (flame fronts) colliding within the combustion chamber. Though light detonation is sometimes considered normal, heavy detonation could result in engine damage.
To control spark knock, a Knock Sensor (KS) system is used. This system is designed to retard spark timing to reduce spark knock in the engine. This allows the engine to use maximum spark advance to improve driveability and fuel economy.
COMPONENTS
The KS system has two major components:
^ KS module.
^ Knock sensor.
OPERATION
The knock sensor detects abnormal vibration (spark knocking) in the engine. The knock sensor is mounted in the engine block near the cylinders and produce an A/C signal under all engine operating conditions. The PCM contains integrated knock sensor (KS) diagnostic circuitry which uses the input signals from the knock sensors to detect engine detonation. This allows the PCM to retard Ignition Control (IC) spark timing based on the amplitude and frequency of the KS signal being received.
DIAGNOSIS
The PCM calculates an average voltage the knock sensor signal and takes instantaneous signal voltage readings. The PCM uses the instantaneous signal voltage reading to determine the state of the knock sensor circuitry. If the knock sensor system is operating normally, the PCM should monitor instantaneous KS signal voltage readings varying outside a voltage range above and below the calculated average voltage. The following DTCs are used to diagnose the knock sensor system:
^ If the PCM malfunctions in a manner which will not allow proper diagnosis of the KS circuits, DTC P0325 will set.
^ DTCs P0327 and P0332 are designed to diagnose the knock sensors, and related wiring, so problems encountered with the KS system should set a DTC. However, if no DTC was set but the KS system is suspect because detonation was the customer's complaint, use the table for P0327 and P0332 to diagnose the Detonation/Spark Knock Symptom. Testing and Inspection
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.