GrandPrix, Impala 2006-2008, Monte Carlo 2006-2007

Knock Sensor

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Operation



The Knock Sensor (KS) system enables the control module to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The control module uses the KS system to test for abnormal engine noise that may indicate detonation, also known as spark knock.

This KS system uses one or two flat response two-wire sensors. The sensor uses piezo-electric crystal technology that produces an AC voltage signal of varying amplitude and frequency based on the engine vibration or noise level. The amplitude and frequency are dependant upon the level of knock that the KS detects. The control module receives the KS signal through a signal circuit. The KS ground is supplied by the control module through a low reference circuit. The control module learns a minimum noise level, or background noise, at idle from the KS and uses calibrated values for the rest of the RPM range. The control module uses the minimum noise level to calculate a noise channel. A normal KS signal will ride within the noise channel. As engine speed and load change, the noise channel upper and lower parameters will change to accommodate the normal KS signal, keeping the signal within the channel. In order to determine which cylinders are knocking, the control module only uses KS signal information when each cylinder is near top dead center (TDC) of the firing stroke. If knock is present, the signal will range outside of the noise channel. If the control module has determined that knock is present, it will retard the ignition timing to attempt to eliminate the knock. The control module will always try to work back to a zero compensation level, or no spark retard. An abnormal KS signal will stay outside of the noise channel or will not be present. KS diagnostics are calibrated to detect faults with the KS circuitry inside the control module, the KS wiring, or the KS voltage output. Some diagnostics are also calibrated to detect constant noise from an outside influence such as a loose/damaged component or excessive engine mechanical noise.

Removal & Installation



3.1L And 3.4L Engines
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the knock sensor electrical connector.
  4.  
  5. Remove the knock sensor from the engine block.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    CAUTION
    DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory and applying additional sealant affects the sensors ability to detect detonation.

  6.  
  7. To install, reverse removal procedure.
  8.  
  9. Tighten the sensor to 14 ft. lbs. (19 Nm).
  10.  

3.5L And 3.9L Engines
  1. Raise and support the vehicle.
  2.  
  3. Disconnect the left knock sensor electrical connector, if required.
  4.  
  5. Disconnect the right knock sensor electrical connector, if required.
  6.  
  7. Loosen and remove the knock sensor.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    CAUTION
    DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory and applying additional sealant affects the sensors ability to detect detonation.

  8.  
  9. To install, reverse removal procedure.
  10.  
  11. Tighten the sensor to 18 ft. lbs. (25 Nm).

    Click image to see an enlarged view

    Fig. Removing and installing knock sensor-3.5L and 3.9L engines

  12.  

3.8L Engine
Bank 1

CAUTION
Hot engine coolant may cause severe burns. Although the cooling system has been drained, coolant still remains in the engine water jacket. This coolant will drain with the removal of the knock sensor.

  1. Raise and support the vehicle.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Disconnect the knock sensor electrical connector (2) and remove the knock sensor (1).
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    CAUTION
    DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory and applying additional sealant affects the sensors ability to detect detonation.

  6.  
  7. To install, reverse removal procedure.
  8.  
  9. Tighten the knock sensor to 14 ft. lbs. (19 Nm).

    Click image to see an enlarged view

    Fig. Removing and installing knock sensor 1-3.8L engines

  10.  

Bank 2

CAUTION
Hot engine coolant may cause severe burns. Although the cooling system has been drained, coolant still remains in the engine water jacket. This coolant will drain with the removal of the knock sensor.

  1. Raise and support the vehicle.
  2.  
  3. Drain and recycle the engine coolant.
  4.  
  5. Remove the bolts (2) from the knock sensor heat shield (1).
  6.  
  7. Disconnect the knock sensor electrical connector (3) and remove the knock sensor.
  8.  
  9. Remove the knock sensor (4).
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.


    CAUTION
    DO NOT apply thread sealant to the sensor threads. The sensor threads are coated at the factory and applying additional sealant affects the sensors ability to detect detonation.

  10.  
  11. To install, reverse removal procedure.
  12.  
  13. Tighten the knock sensor to 44 ft. lbs. (60 Nm).

    Click image to see an enlarged view

    Fig. Removing and installing knock sensor 2-3.8L engines

  14.  

5.3L Engine
Left
  1. Drain and recycle the engine coolant.
  2.  
  3. Disconnect the knock sensor electrical connector.
  4.  
  5. Remove the knock sensor bolt and knock sensor.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  6.  
  7. To install, reverse removal procedure.
  8.  
  9. Tighten the knock sensor to 15 ft. lbs. (20 Nm).

    Click image to see an enlarged view

    Fig. Removing and installing left knock sensor-5.3L engines

  10.  

Right
  1. Drain and recycle the engine coolant.
  2.  
  3. Remove the exhaust manifold.
  4.  
  5. Disconnect the knock sensor electrical connector.
  6.  
  7. Remove the knock sensor bolt and knock sensor.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8.  
  9. To install, reverse removal procedure.
  10.  
  11. Tighten the knock sensor to 15 ft. lbs. (20 Nm).

    Click image to see an enlarged view

    Fig. Removing and installing right knock sensor-5.3L engines

  12.  

Testing



Many intermittent open or shorted circuits come and go with harness and connector movement caused by vibration, engine torque, bumps and rough pavement, etc.

  1. Test the wiring harness and connectors by performing the following:

    Move the related connectors and wiring while monitoring the appropriate scan tool data.
     
    Move the related connectors and wiring with the component commanded ON and OFF, with the scan tool. Observe the components operation.
     
    With the engine running, move the related connectors and wiring while monitoring engine operation
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary
     

  2.  
  3. Test the electrical connections and/or wiring by performing the following:

    Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body, backed-out.
     
    Inspect for improperly formed or damaged terminals. Test for incorrect terminal tension.
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits.
     
    Inspect for wires that are broken inside the insulation.
     

  4.  

 
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