GM Service Manual Online
For 1990-2009 cars only

Note: The intake manifold comprises of an upper and lower section. Some service procedures only require the removal of the upper intake manifold (e.g. fuel injector/spark plug servicing), while other service procedures require the removal of both the upper and lower manifold as a complete assembly (e.g. cylinder head/s). If only the upper intake manifold needs to be removed, refer to Upper Intake Manifold Replacement

Removal Procedure


    Object Number: 1795237  Size: SH
  1. Relieve the fuel system pressure. Refer to Fuel Pressure Relief.
  2. Warning: Refer to Battery Disconnect Warning in the Preface section.

  3. Disconnect the negative battery cable.
  4. Remove the air intake duct.
  5. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement.

  6. Object Number: 1795371  Size: SH
  7. The following precautions must be followed when disconnecting the throttle body wiring connector:
  8. • Do not use any mechanical device such as a screwdriver to disengage the harness connector  (1) from the throttle body (2)
    • When retracting the throttle wiring connector lock (3), take care not to disengage the lock from the connector.
    • Do not pull on the connector wires.
  9. Retract the throttle body wiring connector lock (3).
  10. While pressing the connector latch in the direction of the arrow (4), disconnect the throttle body wiring connector.

  11. Object Number: 1795373  Size: SH
  12. Disconnect the positive crankcase ventilation (PCV) hose (1), evaporative (EVAP) emission purge vacuum hose (2).
  13. Remove the water outlet port-to-surge tank pipe bracket retaining bolts (3).
  14. Remove the EVAP emission purge solenoid bracket retaining bolt (4).

  15. Object Number: 1795375  Size: SH
  16. Disconnect the wiring harness connector from the intake manifold tuning control (IMTC) solenoid.

  17. Object Number: 1795382  Size: SH
  18. Remove the engine wiring harness mount bracket.
  19. Move all the necessary parts clear of the upper intake manifold assembly.

  20. Object Number: 1795481  Size: SH

    Caution: Clean all of the following areas before performing any disconnections in order to avoid possible contamination in the system:

       • The fuel pipe connections
       • The hose connections
       • The areas surrounding the connections

  21. Disconnect the fuel feed line from the fuel rail.

  22. Object Number: 1795492  Size: SH
  23. Remove the wiring harness connector (2) from the EVAP valve (1).
  24. Disconnect the quick connect (3) from the rear of the EVAP valve, as follows:
  25. 16.1. Squeeze the two barbed lugs together, push the quick connect into the valve, then pull out to separate the connection.
    16.2. Plug both open ends to prevent the entry of foreign matter.

    Object Number: 1795497  Size: SH
  26. Remove the bolts securing the complete intake manifold to the cylinder heads.
  27. Note: When the intake manifold is removed, plug each of the cylinder head intake openings with lint free cloth, to stop the entry of foreign material into the intake ports.

  28. Remove the upper and lower intake manifold assembly from the engine.
  29. Remove lower intake manifold to cylinder head gasket.

  30. Object Number: 1795500  Size: SH
  31. Remove the bolts attaching the upper intake manifold to the lower intake manifold.
  32. Remove the upper intake manifold from the lower intake manifold.
  33. Note: Do not reuse the upper to lower intake manifold gaskets.

  34. Remove and discard the upper to lower intake manifold gaskets.

  35. Object Number: 1795502  Size: SH

    Caution: 

       • Use care when servicing the fuel system components, especially the fuel injector electrical connectors, the fuel injector tips, and the injector O-rings. Plug the inlet and the outlet ports of the fuel rail in order to prevent contamination.
       • Do not use compressed air to clean the fuel rail assembly as this may damage the fuel rail components.
       • Do not immerse the fuel rail assembly in a solvent bath in order to prevent damage to the fuel rail assembly.

  36. Remove the fuel rail and injector assembly (1), if necessary. Refer to Fuel Injection Fuel Rail Assembly Replacement.

Cleaning Procedure

    Note: Due to the aluminium alloy construction of the intake manifold, wire brushes and steel scrapers must not be used during the cleaning process, as damage to sealing surfaces may occur. Use of a wooden or plastic scraper is preferred.

  1. Clean mating surfaces ensuring any gasket material is removed.
  2. Clean the manifold using a suitable solvent.
  3. Dry the timing components with compressed air.

Inspection Procedure


    Object Number: 1795386  Size: SH
  1. Inspect the intake manifold for the following fault conditions:
  2. • Damaged sealing and mating surfaces
    • Damaged lower intake manifold gasket
    • Damage or excessive debris on the threaded and through holes
    • Cracks or damage to the intake manifold body
  3. Place a straight edge (1) across the upper intake manifold sealing surface (2).
  4. Using a feeler gage (3), measure the clearance between the manifold and the straight edge.
  5. If the clearance between the upper intake manifold sealing surface and the straight edge exceeds the specified maximum warpage, replace the manifold.
  6. Specification
    Upper manifold maximum warpage : 0.05 mm


    Object Number: 1795388  Size: SH
  7. Place a straight edge (1) across the lower intake manifold sealing surface (2).
  8. Using a feeler gage (3), measure the clearance between the manifold and the straight edge.
  9. If the clearance between the lower intake manifold sealing surface and the straight edge exceeds the specified maximum warpage, replace the manifold.
  10. Specification
    Lower manifold maximum warpage : 0.05 mm

Installation Procedure


    Object Number: 1795541  Size: SH
  1. Install the fuel rail and injector assembly, if necessary. Refer to Fuel Injection Fuel Rail Assembly Replacement
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the lower intake manifold to the cylinder head and tighten the attaching bolts to 23 N·m (17 lb ft).
  4. Install the upper intake manifold to the lower intake manifold and cylinder head and tighten.
  5. • Tighten the upper intake manifold to lower intake manifold attaching bolts to 23 N·m (17 lb ft).
    • Tighten the upper intake manifold to cylinder head attaching bolts to 23 N·m (17 lb ft).

    Object Number: 1795481  Size: SH
  6. Connect the fuel injector connector.
  7. Connect the fuel feed line to the fuel rail.

  8. Object Number: 1795492  Size: SH
  9. Connect the EVAP emission canister purge solenoid valve connector (3) and the quick connector (2).

  10. Object Number: 1795548  Size: SH
  11. Connect the IMTC connector.
  12. Connect the throttle body connector.
  13. Install the EVAP emission purge solenoid bracket retaining bolt.
  14. Install the water outlet port-to-surge tank pipe bracket retaining bolts.
  15. Connect the EVAP emission vacuum hose and PCV hose to the upper intake manifold.

  16. Object Number: 1795237  Size: SH
  17. Install the air intake duct.
  18. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement
  19. Connect the negative battery cable.