GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC P42 Commercial Chassis 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 Camshaft Retard Offset Adjustment

Test Procedure

You cannot adjust the ignition timing. You may need to adjust the distributor in order to prevent crossfire. To insure proper alignment of the distributor, perform the following:

  1. With the ignition OFF, connect the scan tool.
  2. Start the engine. Allow the engine to idle until the engine reaches the normal operating temperature.

    3. Important: The Cam Retard Offset reading will not be accurate below 1,000 RPM.

  3. Increase the engine speed to 1,000 RPM while performing the following steps.
  4. Use the scan tool in order to monitor the Cam Retard Offset.
  5. If the Cam Retard indicates a value of 0 degrees, the distributor is properly adjusted.
  6. If the Cam Retard does not indicate 0 degrees, the distributor must be adjusted.

Adjustment Procedure

    Object Number: 18446 Size: SH
  1. With the engine OFF, slightly loosen the distributor hold down bolt.

    2. Important: The Cam Retard Offset reading will not be accurate below 1,000 RPM.

  2. Start the engine and raise the engine speed to 1,000 RPM.
  3. Use the scan tool in order to monitor the Cam Retard Offset.
  4. Rotate the distributor as follows:
    5. • To compensate for a negative reading, rotate the distributor in the counterclockwise direction.
    • To compensate for a positive reading, rotate the distributor in the clockwise direction.
  5. Repeat step 4 until 0 degrees is obtained.
  6. Turn OFF the ignition.

    7. Notice: 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.

  7. Tighten the distributor hold-down bolt.

    8. Tighten
    Tighten the bolt to 3 N·m (25 lb ft).

  8. Start the engine.
  9. Raise the engine speed to 1,000 RPM and view the Camshaft Retard Offset.