Vue 2002-2005

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 a knock is present, the signal will range outside of the noise channel.

If the control module has determined that a 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, and 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



2.2L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the knock sensor harness connector.
  6.  
  7. Remove the knock sensor connector from the retaining clip by inserting a flat-bladed screwdriver between the connector and clip while sliding the connector upward.
  8.  
  9. Remove the knock sensor.
  10.  

To install:


NOTE
If a new knock sensor pigtail connector retaining clip is going to be used, the old one must be removed from the intake manifold. Use a push pin removal tool to remove the clip from the intake manifold.

  1. Insert the knock sensor pigtail connector with retaining clip into the intake manifold hole or slide the knock sensor pigtail connector over the retaining clip from the top.
  2.  
  3. Connect the knock sensor harness connector. Push in the connector until a click is heard, then pull back to confirm a positive engagement.
    NOTE
    The larger metal contact area of the knock sensor MUST be toward the engine block. The DTC P0327 may result if the sensor is installed backwards.

  4.  
  5. Install the knock sensor at the 9 o'clock position and attachment bolt. Tighten the knock-sensor-engine block bolt to 18 ft. lbs. (25 Nm).
  6.  
  7. Connect the negative battery cable.
  8.  

2.4L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Raise and support the vehicle.
  4.  
  5. Disconnect the engine wiring harness electrical connector from the knock sensor pigtail electrical connector.
  6.  
  7. Remove the knock sensor electrical connector pigtail clip from the oil level indicator tube bracket.
  8.  
  9. Remove the knock sensor bolt.
  10.  
  11. Remove the knock sensor.
  12.  

To install:


NOTE
Rotate the pigtail 90° from vertical before securing the fastener.

  1. Install the knock sensor.
  2.  
  3. Install the knock sensor bolt. Tighten the bolt to 18 ft. lbs. (25 Nm).
  4.  
  5. Connect the engine wiring harness electrical connector to the knock sensor pigtail electrical connector.
  6.  
  7. Install the knock sensor electrical connector pigtail clip to the oil level indicator tube bracket.
  8.  
  9. Lower the vehicle.
  10.  

3.5L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the lower left intake manifold.
  4.  
  5. Disconnect the wiring harness connector from the Knock Sensor (KS).
  6.  
  7. Remove the KS from the engine block.
  8.  

To install:


WARNING
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.

  1. Install the KS into engine block. Tighten the KS to 23 ft. lbs. (31 Nm).
  2.  
  3. Connect the KS wiring harness connector to the knock sensor.
  4.  
  5. Install the lower left intake manifold.
  6.  

Testing





Click image to see an enlarged view

Fig. Knock Sensor (KS) connector end view-2.2L & 2.4L engines



Click image to see an enlarged view

Fig. Knock Sensor (KS) connector end view-3.5L engine

  1. Inspect the Knock Sensor (KS) for physical damage. A KS that is dropped or damaged may cause a DTC to set.
  2.  
  3. Inspect the KS for proper installation. A KS that is loose or over-tightened may cause a DTC to set. The KS should be free of thread sealant other than the factory coating.
  4.  
  5. The KS mounting surface should be free of burrs, casting flash, and foreign material.
    NOTE
    If an engine mechanical noise can be heard, repair the condition before proceeding to test the KS.

  6.  
  7. Test for an intermittent or poor connection at the affected KS.
  8.  
  9. With the ignition OFF, disconnect the affected KS.
    1. Measure the resistance for infinite ohms from the sensor signal terminal on the KS to a good ground with a Digital Multi-Meter (DMM).
    2.  
    3. If resistance does not measure infinite ohms, replace the affected KS.
      WARNING
      DO NOT tap on plastic engine components.

    4.  

  10.  
  11. Connect the DMM to the terminal of the affected KS. Set the DMM to the 400 Hz scale, let it stabilize at 0 Hz.
    1. Tap on engine block with a non-metallic object near the affected KS while observing the signal indicated on the DMM.
    2.  
    3. If the DMM does not display a fluctuating frequency while tapping on the engine block, replace the affected KS.
    4.  

  12.  
  13. Turn the ignition ON, engine OFF. Set the DMM to the DC voltage scale. Measure for 4.2 volts from the KS signal circuit to a good ground with the DMM.
    1. If over 4.2 volts, turn the ignition OFF, disconnect the control module and test the KS signal circuit for a short to voltage.
    2.  
    3. If under 4.2 volts, turn the ignition OFF, disconnect the control module test the KS signal circuit for an open, short to ground, or high resistance.
    4.  

  14.  
  15. Test for intermittent or poor connections at the control module.
  16.  
  17. If all circuits test normal, replace the control module.
  18.  

 
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