GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Catera 🢒 Engine 🢒 Engine Mechanical - 3.0L 🢒 Intake Plenum Replacement

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Remove the Idle Air Control (IAC) inlet hose clamp.
  3. Remove the IAC inlet hose.
  4. Remove the intake plenum air inlet hoses from the throttle body.
  5. Remove the accelerator cable and cruise control cable clips from the throttle body linkage.
  6. Remove the accelerator cable from the bracket.
  7. Remove the accelerator cable and cruise control cable bracket bolts.
  8. Remove the accelerator cable and cruise control cable bracket.
  9. Remove the Throttle Position Sensor (TPS) and IAC electrical connection.
  10. Remove the brake booster threaded vacuum hose from the intake plenum.

    11. Object Number: 158559 Size: SH
  11. Remove the wiring channel bolts (1) from intake plenum.
  12. Remove the electrical connection and vacuum hose (2) from the intake plenum switchover valve solenoid.
  13. Unclip and remove the heater hoses from the bracket on the rear of the intake plenum.
  14. Remove the fuel pressure regulator hose at the intake plenum.

    15. Object Number: 158560 Size: SH
  15. Remove the intake plenum caps and bolts.

    16. Object Number: 158555 Size: SH
  16. Remove the throttle body bolts.

    17. Object Number: 158556 Size: SH
  17. Remove the throttle body from intake plenum.
  18. Remove the crankcase vent tube adapter cover and screw.
  19. Remove the crankcase vent tube adapter from the intake plenum.

    20. Object Number: 158560 Size: SH
  20. Remove the intake plenum.

    21. Important: Mask off the ports to the intake manifold. Severe damage may result if foreign objects enter the engine.

  21. Remove the intake plenum O-rings.

Installation Procedure

    Object Number: 158560 Size: SH
  1. Remove the masking from the plenum ports.
  2. Install the intake plenum O-rings.

    3. Important: Ensure the guide pins on the intake manifold are accurately aligned with the intake plenum.

  3. Install the intake plenum, do not install the bolts at this time.
  4. Install the crankcase vent tube adapter to the intake plenum.

    5. 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.

  5. Install the crankcase vent tube adapter screw.

    6. Tighten
    Tighten the crankcase vent tube adapter screw to 8 N·m (71 lb in).


    Object Number: 158556 Size: SH
  6. Install the throttle body to the intake plenum.

    7. Object Number: 158555 Size: SH
  7. Install the throttle body bolts.

    8. Tighten
    Tighten the throttle body bolts to 12 N·m (106 lb in).


    Object Number: 158560 Size: SH
  8. Install the intake plenum bolts.

    9. Tighten
    Tighten the intake plenum bolts to 20 N·m (15 lb ft).

  9. Install the intake plenum caps.
  10. Install the vacuum hose to the fuel pressure regulator.
  11. Install the electrical connection and vacuum hose to the intake plenum switchover valve solenoid.

    12. Object Number: 158559 Size: SH
  12. Install the wiring channel bolts (1) to intake plenum.

    13. Tighten
    Tighten the wiring channel bolts to 8 N·m (71 lb in).

  13. Install the heater hoses to the bracket on the rear of the plenum and clip in place.
  14. Install the brake booster threaded vacuum hose (2) to the intake plenum.

    15. Tighten
    Tighten the brake booster threaded vacuum hose until fully seated. Do not strip the brake booster threaded hose.

  15. Install the TPS electrical connection.
  16. Install the accelerator cable and cruise control cable bracket.
  17. Install the accelerator cable and cruise control cable bracket bolts.

    18. Tighten
    Tighten the accelerator cable and cruise control cable bracket bolts to 8 N·m (71 lb in).

  18. Install the accelerator cable to the bracket.
  19. Install the accelerator cable and cruise control cable to the throttle body linkage.
  20. Install the intake plenum air inlet hoses to the throttle body.
  21. Install the IAC inlet hose and electrical connection.
  22. Install the IAC inlet hose clamp.
  23. Connect the negative battery cable.
  24. Reprogram the applicable accessories.