CTS 2006-2007, CTS-V 2005-2007, DTS 2006-2007

Intake Manifold

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Removal & Installation



2.8L & 3.6L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove or disconnect the following:

    Engine shroud
     
    Air intake assembly
     
    Brake booster vacuum hose from manifold
     
    Purge solenoid valve electrical connector
     
    Throttle body electrical connector
     
    Upper intake manifold brace
     
    Positive Crankcase Valve (PCV) hose from the camshaft cover
     
    Barometric pressure (BARO) sensor electrical connector
     
    Intake manifold runner control solenoid electrical connector
     
    Left bank ignition coil harness
     
    Fuel injector harness bracket
     
    Intake manifold bolts
     
    Intake manifold assembly
     

  4.  
  5. To disassemble the intake manifold:
    1. Remove the upper-to-lower intake manifold bolts.
    2.  
    3. Remove the fuel injector wiring harness bracket bolt from the upper intake manifold
    4.  
    5. Remove the upper intake manifold from the lower intake manifold.

      Click image to see an enlarged view

      Fig. View of the intake manifold-2.8L and 3.6L

    6.  

  6.  

To install:

  1. If necessary, assembly the intake manifold:
    1. Install the upper manifold to the lower manifold using a new gasket.
    2.  
    3. Install the fuel injector wiring harness bracket bolt. Tighten to 89 inch lbs. (10 Nm).
    4.  
    5. Tighten the upper-to-lower intake manifold bolts to 17 ft. lbs. (23 Nm).
    6.  

  2.  
  3. Install the intake manifold with a new gasket. Tighten the bolts to 17 ft. lbs. (23 Nm).
  4.  
  5. Install or connect the following:

    Fuel injector harness bracket. Tighten bolt to 89 inch lbs. (10 Nm).
     
    Left bank ignition coil harness
     
    BARO sensor electrical connector
     
    Intake manifold runner control solenoid electrical connector
     
    PCV hose to the camshaft cover
     
    Upper intake manifold brace. Tighten bolts to 48 ft. lbs. (65 Nm).
     
    Throttle body electrical connector
     
    Purge solenoid valve electrical connector
     
    Brake booster vacuum hose to the manifold
     
    Air intake assembly
     
    Engine shroud
     

  6.  
  7. Start the engine and check for leaks.
  8.  

4.6L Engine
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the fuel injector sight shield cover.
  4.  
  5. Remove the air cleaner outlet duct.
  6.  
  7. Disconnect the front ignition coil module engine harness electrical connector.
  8.  
  9. Disconnect the front fuel injectors engine harness electrical connectors.
  10.  
  11. Disconnect the rear ignition coil module engine harness electrical connector.
  12.  
  13. Disconnect the rear fuel injectors engine harness electrical connectors.
  14.  
  15. Disconnect the Positive Crankcase Ventilation (PCV) foul air tube quick connect fitting from the right camshaft cover.
  16.  
  17. Disconnect the PCV fresh air tube quick connect fitting from the camshaft cover.
  18.  
  19. Disconnect the fuel feed line quick connect fitting at the fuel rail.
  20.  
  21. Reposition the radiator surge tank inlet hose/pipe clamp at the surge tank.
  22.  
  23. Remove the surge tank inlet hose/pipe from the surge tank.
  24.  
  25. Reposition the radiator surge tank inlet hose/pipe clamp at the engine.
  26.  
  27. Remove the surge tank inlet hose/pipe from the engine fitting.
  28.  
  29. Remove the 2 push nuts securing the surge tank inlet hose/pipe to the fuel rail studs.
  30.  
  31. Remove the surge tank inlet hose/pipe from the fuel rail studs.
  32.  
  33. Remove the engine harness retainer from the fuel rail stud.
  34.  
  35. Remove the coolant heater cord tabs from the fuel rail studs, if equipped.
  36.  
  37. Remove the fuel rail bracket nut at the rear left lift bracket.
  38.  
  39. Remove the fuel rail studs.
  40.  
  41. Remove the fuel rail.
  42.  
  43. Loosen the plenum duct clamp screw at the water pump housing.
  44.  
  45. Remove intake manifold bolts.
  46.  
  47. Position the power steering aside.
  48.  
  49. Remove the intake manifold.

    Click image to see an enlarged view

    Fig. View of the 4.6L intake manifold removal

  50.  
  51. Disconnect the PCV foul air tube quick connect fitting at the intake manifold.
  52.  
  53. Remove the PCV foul air tube from the retaining features on the intake manifold.
  54.  
  55. Remove and discard the old seals.
  56.  
  57. Clean and inspect the intake manifold.
  58.  

To install:

  1. Install the new intake manifold seals.
  2.  
  3. Connect the PCV foul air tube quick connect fitting at the intake manifold.
  4.  
  5. Install the PCV foul air tube to the retaining features on the intake manifold.
  6.  
  7. Lightly grease the inside edge of the rubber plenum duct on the water pump housing.
  8.  
  9. Install the intake manifold.
  10.  
  11. Install intake manifold bolts until snug.
  12.  
  13. Tighten the intake manifold bolts.
  14.  
  15. Tighten the bolts in the sequence to 89 inch lbs. (10 Nm).

    Click image to see an enlarged view

    Fig. Intake manifold tightening sequence-4.6L

  16.  
  17. Ensure that the intake manifold is fully installed into the plenum duct on the water pump housing.
  18.  
  19. Install the power steering pump
  20.  
  21. Tighten the plenum duct clamp screw at the water pump housing to 24 inch lbs. (2.75 Nm).
  22.  
  23. Lubricate the fuel injector lower O-ring seals with clean engine oil.
  24.  
  25. Install the fuel rail.
  26.  
  27. Install the fuel rail studs and tighten to 89 inch lbs. (10 Nm).
  28.  
  29. Install the fuel rail bracket nut at the rear left lift bracket and tighten to 89 inch lbs. (10 Nm).
  30.  
  31. Install the coolant heater cord tabs to the fuel rail studs, if equipped.
  32.  
  33. Install the engine harness retainer to the fuel rail stud.
  34.  
  35. Install the surge tank inlet hose/pipe to the fuel rail studs.
  36.  
  37. Install the 2 push nuts securing the surge tank inlet hose/pipe to the fuel rail studs.
  38.  
  39. Install the surge tank inlet hose/pipe to the engine fitting.
  40.  
  41. Position the radiator surge tank inlet hose/pipe clamp at the engine.
  42.  
  43. Install the surge tank inlet hose/pipe to the surge tank.
  44.  
  45. Position the radiator surge tank inlet hose/pipe clamp at the surge tank.
  46.  
  47. Connect the fuel feed line quick connect fitting at the fuel rail.
  48.  
  49. Connect the PCV fresh air tube quick connect fitting to the camshaft cover.
  50.  
  51. Connect the PCV foul air tube quick connect fitting to the right camshaft cover.
  52.  
  53. Connect the rear fuel injectors engine harness electrical connectors.
  54.  
  55. Connect the rear ignition coil module engine harness electrical connector.
  56.  
  57. Connect the front fuel injectors engine harness electrical connectors.
  58.  
  59. Connect the front ignition coil module engine harness electrical connector.
  60.  
  61. Install the air cleaner outlet duct.
  62.  
  63. Install the fuel injector sight shield cover.
  64.  

5.7L Engine

NOTE
The intake manifold, throttle body, fuel rail and injectors may be removed as an assembly.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Drain the cooling system.
  4.  
  5. Relieve the fuel system pressure.
  6.  
  7. Remove or disconnect the following:

    Negative battery cable
     
    Engine shroud
     
    Air intake assembly
     
    Fuel supply hose
     
    Evaporative emissions (EVAP) canister purge hose
     
    Throttle position (TP) sensor
     
    Coolant air bleed hose
     
    Throttle body outlet hose from the throttle body
     
    Fuel injector electrical connectors
     
    Electronic throttle control (ETC) electrical connector
     
    EVAP canister purge solenoid valve
     
    Power brake booster vacuum hose at the booster
     
    Knock sensor
     
    TP sensor from the Positive Crankcase Ventilation (PCV) hose
     
    PCV hose from rocker arm cover and throttle body
     
    PCV hose from intake manifold and valley cover
     
    Intake manifold mounting bolts and fuel rail stop bracket
     

  8.  
  9. Slide the intake manifold forward.
  10.  
  11. Remove or disconnect the following:

    Manifold absolute pressure (MAP) sensor vacuum hose
     
    MAP sensor
     
    Intake manifold
     

  12.  

To install:

  1. Install the intake manifold with new gaskets. Slide the intake manifold forward.
  2.  
  3. Connect the MAP sensor vacuum hose
  4.  
  5. Connect the MAP sensor
  6.  
  7. Position the intake manifold into place.
  8.  
  9. Apply a thread locking compound to the intake manifold bolts. Tighten the bolts as follows:
    1. Step 1: Tighten the bolts in sequence to 44 inch lbs. (5 Nm).
    2.  
    3. Step 2: Tighten the bolts in sequence to 89 inch lbs. (10 Nm).

      Click image to see an enlarged view

      Fig. Intake manifold sequence-5.7L

    4.  

  10.  
  11. Install or connect the following:

    PCV hose to the valley cover and intake manifold
     
    PCV hose to the throttle body and right rocker arm cover
     
    TP sensor to the PCV hose
     
    Knock sensor
     
    Power brake booster vacuum hose
     
    EVAP canister purge solenoid valve
     
    ETC electrical connector
     
    Fuel injector electrical connectors
     
    Throttle body outlet hose to the throttle body
     
    Coolant air bleed hose
     
    TP sensor
     
    EVAP canister purge hose
     
    Fuel supply hose
     
    Air intake assembly
     
    Engine shroud
     
    Negative battery cable
     

  12.  
  13. Start the engine and check for leaks.
  14.  

6.0L Engine

NOTE
The intake manifold, throttle body, fuel injection rail and fuel injectors may be removed as an assembly. If not servicing the individual components, install the intake manifold as a complete assembly.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Remove the engine sight shield.
  4.  
  5. Remove the air cleaner outlet duct.
  6.  
  7. Disconnect the fuel injector electrical connectors.
  8.  
  9. Disconnect the throttle body electrical connector.
  10.  
  11. Relieve the fuel system pressure.
  12.  
  13. Remove the engine compartment fuel feed pipe.
  14.  
  15. Remove the fuel rail if necessary.
  16.  
  17. Remove the vacuum hose from the intake manifold. Position the hose aside.
  18.  
  19. Disconnect the electrical connector from the manifold absolute pressure (MAP) sensor.
  20.  
  21. Remove the MAP sensor.
  22.  
  23. Remove the grommet from the sensor, as required.
  24.  
  25. Remove the evaporative emission (EVAP) clip, bolt, bracket, valve, and tubes.
  26.  
  27. Remove the intake manifold bolts and fuel rail stop bracket.
  28.  
  29. Remove and discard the intake manifold gaskets.
  30.  
  31. Disassemble the intake manifold as necessary. Refer to the appropriate procedures.
  32.  
  33. Clean and inspect the intake manifold if it is not being replaced.
  34.  

To install:

  1. Install NEW intake manifold-to-cylinder head gaskets 
  2.  
  3. Install the intake manifold.
  4.  
  5. Apply a 5 mm (0.20 in) band of threadlocker to the threads of the intake manifold bolts.
  6.  
  7. Install the fuel rail stop bracket. 
  8.  
  9. Install the intake manifold bolts as follows:
    1. First pass: tighten intake manifold bolts in sequence to 44 inch lbs. (5 Nm)
    2.  
    3. Final pass: tighten the intake manifold bolts in sequence to 89 inch lbs. (10 Nm).

      Click image to see an enlarged view

      Fig. Intake manifold tightening sequence-6.0L

    4.  

  10.  
  11. Lubricate the MAP sensor grommet with clean engine oil.
  12.  
  13. Install the MAP sensor and grommet.
  14.  
  15. Install the EVAP valve, bracket, and bolt. Tighten the bolt to 37 ft. lbs. (50 Nm).
  16.  
  17. Install the EVAP tubes.
  18.  
  19. If previously removed, install the fuel rail.
  20.  
  21. Connect the MAP sensor electrical connector.
  22.  
  23. Install the brake booster vacuum hose to the intake manifold.
  24.  
  25. Connect the throttle body electrical connector.
  26.  
  27. Connect the fuel injector electrical connectors.
  28.  
  29. Install the air cleaner outlet duct.
  30.  
  31. Install the engine sight shield.
  32.  

 
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