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Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
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Experience:  Have owned a repair shop for 25 yrs.
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2001 Chevy Impala with 3800 V6 engine..Problem is during warm-up

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2001 Chevy Impala with 3800 V6 engine..158,000 miles..Problem is during warm-up period til reaching normal operating temp..obvious skip (tach fluctuates) and the shift from 2nd gear to 3rd is harsh..as it warms up..shift from 3rd to overdrive is harsh..After operating temp is achieved..car runs perfectly normal..all shifting is smooth...Car is hard to restart at times when warm..tries to catch..stalls with a whooshing sound as it stalls...Have replaced plugs,wires, fuel filter, air filter...No codes have been found...

hi

this sounds as if you may have a bad crank sensor..these will do this with heat when they go bad,and not give a code

thanks

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Crankshaft Position (CKP) Sensor Replacement

REMOVAL PROCEDURE


 

  1. Disconnect the negative battery cable.
  2. Raise the vehicle on a hoist.
  3. Remove the right splash shield cover.
  4. Remove the crankshaft harmonic balancer.
  5. Remove the crankshaft position sensor (CKP) shield (1). Do Not use a pry bar.
  6. Disconnect the sensor electrical connector.

 


 

  1. Remove 2 attaching bolts from the CKP sensor.
  2. Remove the CKP sensor from the block face.

INSTALLATION PROCEDURE


 

  1. Position the CKP sensor to the block.
  2. Install the bolts that hold the CKP sensor to the block face. Tighten Tighten the bolts to 30 N.m (22 lb ft) .

 


 

  1. Install the CKP sensor shield (1).
  2. Connect the CKP sensor electrical connector.
  3. Position the crankshaft harmonic balancer on the crankshaft. Refer to Crankshaft Balancer Replacement in Engine Mechanical - 3.8 L.
  4. Install the right splash shield cover.
  5. Lower the vehicle.
  6. Connect the negative battery cable.
  7. Perform the Crankshaft Variation Learn Procedure. Refer to CKP System Variation Learn Procedure.
CKP System Variation Learn Procedure

The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position system variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set, refer to Diagnostic Aids for DTC P0300.

The Crankshaft Position System Variation Learn Procedure should be performed if any of the following conditions are true.

  • DTC P1336 is set
  • The PCM has been replaced
  • The engine has been replaced
  • The crankshaft has been replaced
  • The crankshaft harmonic balancer has been replaced
  • The crankshaft position sensor has been replaced

IMPORTANT:

  • Set the vehicle parking brake and block the drive wheels when performing the Crankshaft Position System Variation Learning Procedure in order to prevent personal injury. Release the throttle when the engine reaches the SECOND fuel cut off. Leaving the throttle open during the fuel cut off will allow the engine to decel at an even rate. Once the learn procedure is completed, the PCM will return the engine control to the operator and the engine will respond to the throttle position.
  • The scan tool crankshaft position system variation learn function will be inhibited if engine coolant temperature is less than 70°C (158°F) . Allow the engine to warm to at least 70°C (158°F) before attempting the crankshaft position system variation learn procedure.

The scan tool crankshaft position system variation learn function will be inhibited if any powertrain DTCs other than DTC P1336 are set before or during the Crankshaft Position System Variation Learn Procedure. Diagnose and repair any DTCs if set.

The crankshaft position system variation learn function will be inhibited if the PCM detects a malfunction involving the camshaft position signal circuit, the 3X reference circuit, or the 18X reference circuit.

  • If the scan tool indicates a problem with the cam signal, refer to DTC P0341.
  • If the scan tool indicates a problem with the 3X crank signal, refer to DTC P1374.
  • If the scan tool indicates a problem with the 18X crank signal, refer to DTC P0336.
  1. Set the parking brake.
  2. Block the driver wheels.
  3. Ensure that the hood is closed.
  4. Start the engine and allow engine coolant temperature to reach at least 70°C (158°F) .
  5. Turn OFF the ignition.
  6. Select and enable the Crankshaft Position Variation Learn Procedure with the scan tool.
  7. Start the vehicle.
  8. Apply and hold the service brake pedal firmly.
  9. Ensure that the transaxle is in Park.
  10. Increase accelerator pedal position until CKP system variation learn fuel cutoff is reached. CKP system variation learn fuel cutoff is reached at 5150 RPM . Release the accelerator pedal when the second fuel cutoff is reached.
  11. The crankshaft position system variation compensating values are learned when RPM decreases back to idle. If the procedure terminates, refer to Important above for instructions.
  12. Observe DTC status for DTC P1336.
  13. If the scan tool indicates that DTC P1336 ran and passed, the Crankshaft Position System Variation Learn Procedure is complete. If the scan tool indicates DTC P1336 failed or did not run, check for other DTCs. If no DTCs other than P1336 are set, repeat the Crankshaft Position System Variation Learn Procedure as necessary.
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