Lexus Car ES, IS, LS 1998-06

Camshaft Position Sensor

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Description & Operation



4.0L

The Camshaft Position Sensor (CMP) on the 4.0L 6cylinder engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter.

The CMP sensor contains a Hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects a rotating pulse ring (shutter) on the oil pump drive shaft. The pulse ring rotates 180 degrees through the sync signal generator. Its signal is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

When the leading edge of the pulse ring (shutter) enters the sync signal generator, the following occurs: The interruption of magnetic field causes the voltage to switch high resulting in a sync signal of approximately 5 volts.

When the trailing edge of the pulse ring (shutter) leaves the sync signal generator, the following occurs: The change of the magnetic field causes the sync signal voltage to switch low to 0 volts.

Click image to see an enlarged view

Fig.

4.7L

The Camshaft Position Sensor (CMP) on the 4.7L V8 engine is bolted to the front/top of the right cylinder head.

The CMP sensor contains a Hall effect device called a sync signal generator to generate a fuel sync signal. This sync signal generator detects notches located on a tone wheel. The tone wheel is located at the front of the camshaft for the right cylinder head. As the tone wheel rotates, the notches pass through the sync signal generator. The pattern of the notches (viewed counter-clockwise from front of engine) is: 1 notch, 2 notches, 3 notches, 3 notches, 2 notches 1 notch, 3 notches and 1 notch. The signal from the CMP sensor is used in conjunction with the crankshaft position sensor to differentiate between fuel injection and spark events. It is also used to synchronize the fuel injectors with their respective cylinders.

Click image to see an enlarged view

Fig.

Removal & Installation



4.0L Engine

Sensor Only

The Camshaft Position Sensor (CMP) on the 4.0L 6cylinder engine is bolted to the top of the oil pump drive shaft assembly. The sensor and drive shaft assembly is located on the right side of the engine near the oil filter.

  1. Install sensor to oil pump drive.
  2.  
  3. Install 2 sensor mounting bolts and tighten to 2 Nm (15 inch lbs.) torque.
  4.  
  5. Connect electrical connector to CMP sensor.
  6.  

Oil Pump Drive & Sensor

  1. Clean oil pump drive mounting hole area of engine block.
  2.  
  3. Install new oil pump drive-to-engine block gasket.
  4.  
  5. Temporarily install a toothpick or similar tool through access hole at side of oil pump drive housing. Align toothpick into mating hole on pulse ring.
  6.  
  7. Install oil pump drive into engine while aligning into slot on oil pump. Rotate oil pump drive back to its original position and install hold-down clamp and bolt. Finger-tighten bolt. Do NOT do a final tightening of bolt at this time.
  8.  
  9. If engine crankshaft or camshaft has been rotated, such as during engine tear-down, CMP sensor relationship must be reestablished.
  10.  
  11. Remove ignition coil rail assembly.
  12.  
  13. Remove cylinder number 1 spark plug.
  14.  
  15. Hold a finger over the open spark plug hole. Rotate engine at vibration dampener bolt until compression (pressure) is felt.
  16.  
  17. Slowly continue to rotate engine.
    NOTE
    Do this until timing index mark on vibration damper pulley aligns with top dead center (TDC) mark (0 degree) on timing degree scale. Always rotate engine in direction of normal rotation. Do NOT rotate engine backward to align timing marks.

  18.  
  19. Install oil pump drive into engine while aligning into slot on oil pump. If pump drive will not drop down flush to engine block, the oil pump slot is not aligned. Remove oil pump drive and align slot in oil pump to shaft at bottom of drive. Install into engine. Rotate oil pump drive back to its original position and install hold-down clamp and bolt. Finger-tighten the bolt. Do NOT do a final tightening of bolt at this time.
  20.  
  21. Remove toothpick from housing.
  22.  
  23. Install sensor to oil pump drive. After installation:, the CMP sensor should face rear of engine: 0.
  24.  
  25. Install 2 sensor mounting bolts and tighten to 2 Nm (15 inch lbs.) torque. Connect electrical connector to CMP sensor.
  26.  
  27. If removed, install spark plug and ignition coil rail.
  28.  
  29. To verify correct rotational position of oil pump drive, the DRB scan tool must be used.
    CAUTION
    When performing the following test, the engine will be running. Be careful not to stand in line with the fan blades or fan belt. Do NOT wear loose clothing.

  30.  
  31. Connect the scan tool to data link connector. The data link connector is located in passenger compartment, below and to left of steering column.
  32.  
  33. Gain access to SET SYNC screen on the scan tool.
  34.  
  35. Follow the directions on the scan tool screen and start engine. Bring to operating temperature (engine must be in closed loop mode).
  36.  
  37. With engine running at idle speed, the words IN RANGE should appear on the scan tool screen along with 0. This indicates correct position of oil pump drive.
  38.  
  39. If a plus (+) or a minus (-) is displayed next to degree number, and/or the degree displayed is not zero, loosen, but do NOT remove hold-down clamp bolt. Rotate oil pump drive until IN RANGE appears on screen. Continue to rotate oil pump drive until achieving as close to 0 as possible.
    NOTE
    The degree scale on SET SYNC screen of the scan tool is referring to fuel synchronization only. It is not referring to ignition timing. Because of this, do NOT attempt to adjust ignition timing using this method. Rotating oil pump drive will have no effect on ignition timing. All ignition timing values are controlled by powertrain control module (PCM).

  40.  
  41. Tighten hold-down clamp bolt to 23 Nm (17 ft. lbs.) torque.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  42.  

4.7L

The Camshaft Position Sensor (CMP) on the 4.7L V8 engine is bolted to the front/top of the right cylinder head.


NOTE
It is easier to remove/install sensor from under vehicle.

  1. Raise and support vehicle.
  2.  
  3. Disconnect electrical connector at CMP sensor.
  4.  
  5. Remove sensor mounting bolt.
  6.  
  7. Carefully twist sensor from cylinder head. Check condition of sensor O-ring.
    NOTE
    Some 4.7L are equipped with a sensor spacer shim. If equipped, this shim will be located at sensor bolt hole, between the cylinder head and sensor mounting tang. Save this shim for installation.

  8.  

 
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