GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Firebird 🢒 Engine 🢒 Engine Mechanical - 3.8L 🢒 Upper Intake Manifold Replacement

Removal Procedure

    Object Number: 208554 Size: SH
  1. Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
  2. Disconnect the intake air temperature (IAT) sensor electrical connector.

    3. Object Number: 554755 Size: SH
  3. Remove the air intake duct.
  4. Remove the drive belt tensioner. Refer to Drive Belt Tensioner Replacement .

    5. Object Number: 439410 Size: SH
  5. Disconnect the right side fuel injector electrical connectors (1) from the fuel injectors.
  6. Disconnect the manifold absolute pressure (MAP) sensor electrical connector (2).

    7. Object Number: 439411 Size: SH
  7. Remove the engine harness vacuum tube (1) from the vacuum port.

    8. Object Number: 439396 Size: SH
  8. Remove the fuel pressure regulator tube (2) from the following components:
    9. • Manifold vacuum source (1)
    • Fuel pressure regulator valve (3)

    Object Number: 439467 Size: SH
  9. Disconnect the left side fuel injector electrical connectors (1) from the fuel injectors.
  10. Disconnect the evaporative emission (EVAP) canister purge valve switch electrical connector (2).
  11. Relieve the fuel pressure. Refer to Fuel Pressure Relief in Engine Controls-3.8L.
  12. Disconnect the fuel lines from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service in Engine Controls-3.8L.
  13. Disconnect the fuel vapor line from the EVAP canister purge valve. Refer to Plastic Collar Quick Connect Fitting Service in Engine Controls-3.8L.
  14. Remove the ignition control module. Refer to Ignition Control Module Replacement in Engine Controls-3.8L.

    15. Object Number: 439407 Size: SH
  15. Reposition the brake booster hose clamp.
  16. Remove the brake booster hose (2) from the upper intake manifold fitting (1).

    17. Object Number: 439418 Size: SH
  17. Disconnect the electronic throttle control (ETC) electrical connector  (1).

    18. Object Number: 439428 Size: SH
  18. Disconnect the following electrical connectors:
    19. • Mass airflow (MAF) sensor (1)
    • Engine coolant temperature (ECT) sensor (2)
  19. Remove the engine harness clip (3) from the throttle body.
  20. Remove the engine harness clamp bolt (5) and harness clamp (4).
  21. Reposition the engine wiring harness.
  22. Remove the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement in Engine Cooling.
  23. Remove the wiring harness clips from the fuel rail.
  24. Reposition the wiring harness.

    25. Object Number: 441253 Size: SH
  25. Remove the fuel rail nuts (1).

    26. Important: Clean any dirt out of the injector bores with compressed air.

  26. Remove the fuel rail (2) from the upper intake manifold.

    27. Object Number: 441255 Size: SH
  27. Remove the upper intake manifold bolts (1, 3, 4).
  28. Remove the upper intake manifold (2).

    29. Object Number: 439503 Size: SH
  29. Remove the upper intake manifold gasket (1).
  30. Clean the upper and lower intake manifold mating surfaces.

    31. Object Number: 441250 Size: SH
  31. If replacing the manifold remove the manifold vacuum source screws (2) and manifold vacuum source (1).

    32. Object Number: 439395 Size: SH
  32. If replacing the manifold remove the EVAP purge valve bolts (1) and purge valve (2).

    33. Object Number: 439449 Size: SH
  33. If replacing the manifold remove the throttle body bolt (1), nuts (2), throttle body (3) and gasket (4).

    34. Object Number: 439510 Size: SH
  34. Remove the lower intake manifold O-rings seals (3, 4), if necessary.

Installation Procedure

    Object Number: 439510 Size: SH
  1. Install new lower intake manifold O-ring seal (3, 4), if removed.

    2. Object Number: 439503 Size: SH
  2. Install the upper intake manifold gasket (1).

    3. Object Number: 441255 Size: SH
  3. Install the upper intake manifold (2) onto the lower intake manifold.

    4. 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.

  4. Install the upper intake manifold bolts (1, 3, 4).

    5. Tighten

        • Tighten the 9 upper intake manifold bolts (4) to 15 N·m (11 lb ft).
        • Tighten the 2 upper intake manifold bolts (1) to 30 N·m (22 lb ft).
        • Tighten the upper intake manifold bolt (3) to 15 N·m (11 lb ft).

    Object Number: 439449 Size: SH
  5. If the upper intake manifold was replaced install the throttle body gasket (4) and the throttle body (3) .
  6. Install the throttle body bolt (1) and nuts (2).

    7. Tighten

        • Tighten the throttle body nuts (2) to 10 N·m (89 lb in).
        • Tighten the throttle body bolt (1) to 10 N·m (89 lb in).

    Object Number: 441253 Size: SH
  7. Install the fuel rail (2) to the upper intake manifold.
  8. Install the fuel rail nuts (1).

    9. Tighten
    Tighten the fuel rail nuts (1) to 9 N·m (80 lb in).

  9. Install the wiring harness clips to the fuel rail.
  10. Install the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement in Engine Cooling.
  11. Reposition the engine wiring harness.

    12. Object Number: 439428 Size: SH
  12. Install the engine harness clamp (4) and harness clamp bolt (5).

    13. Tighten
    Tighten the harness clamp bolt (5) to 6 N·m (53 lb in).

  13. Install the engine harness clip (3) to the throttle body.
  14. Connect the following electrical connectors:
    15. • MAF sensor (1)
    • ECT sensor (2)

    Object Number: 439418 Size: SH
  15. Connect the ETC electrical connector (1).

    16. Object Number: 439407 Size: SH
  16. Install the brake booster hose (2) to the upper intake manifold fitting (1).
  17. Position the brake booster hose clamp.
  18. Install the ignition control module. Refer to Ignition Control Module Replacement in Engine Controls-3.8L.

    19. Object Number: 439395 Size: SH
  19. If the upper intake manifold was replaced install the EVAP canister purge valve (2) to the upper intake manifold.
  20. Install the EVAP canister purge valve bolts (1).

    21. Tighten
    Tighten the EVAP canister purge valve bolts (1) to 10 N·m (89 lb in).


    Object Number: 439398 Size: SH
  21. Install the fuel vapor line (4) to the EVAP canister purge valve (5).
  22. Install the fuel lines (1) to the fuel rail.

    23. Object Number: 439467 Size: SH
  23. Connect the EVAP canister purge valve electrical connector (2).
  24. Connect the left side fuel injector electrical connectors (1) to the fuel injectors.

    25. Object Number: 441250 Size: SH
  25. If the upper intake manifold was replaced install the manifold vacuum source (1) to the upper intake manifold.
  26. Install the manifold vacuum source screws (2).

    27. Tighten
    Tighten the manifold vacuum source screws (2) to 10 N·m (89 lb in).


    Object Number: 439396 Size: SH
  27. Install the fuel pressure regulator tube (2) to the following components:
    28. • Manifold vacuum source (1)
    • Fuel pressure regulator valve (3)

    Object Number: 439411 Size: SH
  28. Install the engine harness vacuum tube (1) to the vacuum port.

    29. Object Number: 439410 Size: SH
  29. Connect the MAP sensor electrical connector (2).
  30. Connect the right side fuel injector electrical connectors (1) to the fuel injectors.
  31. Install the drive belt tensioner. Refer to Drive Belt Tensioner Replacement .

    32. Object Number: 554755 Size: SH
  32. Install the air intake duct.

    33. Object Number: 208554 Size: SH
  33. Connect the IAT sensor electrical connector.
  34. Refill the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.