GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 Engine 🢒 Engine Electrical 🢒 Intake Manifold Cleaning and Inspection

Cleaning Procedure

    Object Number: 58838 Size: SH

    Important: Do not use the intake manifold-to-cylinder head sealing gaskets again.

  1. Remove the manifold absolute pressure (MAP) sensor from the rear of the intake. The MAP sensor is to be installed upon completion of the cleaning and inspection procedures.
  2. Inspect the sealing grommet on the MAP sensor. The grommet should not be torn or damaged.

    3. Object Number: 1286454 Size: SH
  3. Remove the throttle body and bolts.

    4. Object Number: 1272781 Size: SH
  4. Remove the throttle body gasket (509).
  5. Discard the gasket.

    6. Object Number: 1272618 Size: SH
  6. Remove the accelerator control cable bracket and bolts, if required.

    7. Object Number: 222050 Size: SH
  7. Remove the fuel rail with injectors.

    8. Refer to Fuel Rail and Injectors Removal .


    Object Number: 1272799 Size: SH
  8. Remove and discard the intake manifold-to-cylinder head gaskets (514).

    9. Object Number: 639607 Size: SH
  9. Clean the intake manifold in solvent.
    10. • Clean the intake manifold gasket grooves.
    • Clean the intake manifold vacuum passages at the rear of the intake.

    Caution: Refer to Safety Glasses Caution in the Preface section.

  10. Dry the intake manifold with compressed air.
  11. Upon installation of the intake manifold, install NEW manifold-to-cylinder head gaskets.

Inspection Procedure

    Object Number: 222051 Size: SH
  1. Inspect the throttle body bolt inserts for looseness or damaged threads.

    2. Object Number: 222050 Size: SH
  2. Inspect the fuel rail bolt inserts for looseness or damaged threads.
  3. Inspect the intake manifold vacuum passages for debris or restrictions.

    4. Object Number: 58838 Size: SH

    Important: 

       • The rear manifold absolute pressure (MAP) sensor housing is retained to the intake manifold by push-in-place snap lock design.
       • The rear MAP sensor housing is sealed at the intake manifold by an O-ring seal.

  4. Inspect the rear MAP sensor housing.
    5. • Inspect for damaged or broken vacuum fittings, damaged MAP sensor mounting bore, or broken MAP sensor retaining tab.
    • Inspect the rear MAP sensor housing for looseness or poor sealing to the intake manifold. Repair or replace the components as necessary.
  5. Inspect the composite intake manifold assembly for cracks or damage.

    6. Inspect the areas between the intake runners.

  6. Inspect all the gasket sealing surfaces and grooves for cracking or damage.

    7. Object Number: 222050 Size: SH
  7. Inspect the fuel injector bores for excessive scoring or damage.
  8. Inspect the intake manifold cylinder head deck for warpage.
    9. 8.1. Locate a straight edge across the intake manifold cylinder head deck surface.
    8.2. Insert a feeler gage between the intake manifold and the straight edge.

    An intake manifold with warpage in excess of 0.5 mm (0.02 in), must be replaced.

  9. Upon completion of inspection, install the MAP sensor to the manifold.