Upper Manifold Assembly
Upper And Lower Manifold Assemblies:
Upper And Lower Manifold Assembly-Part Name:
NOTE: A label containing the last four digits of the upper manifold assembly identification number appears above the power brake fitting assembly as shown. The bar code (read by an optical scanner) also contains the component number for manifolds, and the four digits of the identifying number. Refer to this number if servicing or part replacement is required. Refer to the disassembled view for identification of parts during repair procedures.
REMOVE OR DISCONNECT
1. Negative battery cable.
2. Air intake duct.
3. Accelerator cable splash shield from accelerator cable bracket.
4. Accelerator, cruise, and transmission control cables.
5. Vacuum hose harness from top of air inlet.
6. Disconnect crankcase ventilation valve and power brake vacuum hoses from vacuum tubes at upper manifold.
- Position vacuum hoses out of the way.
7. Electrical connectors at Manifold Absolute Pressure (MAP) sensor, Throttle Position (TP) sensor, and Idle Air Control (IAC) valve.
8. Bolts/nuts attaching throttle cable bracket.
- Position bracket and cables out of the way.
9. Bolts/studs attaching upper manifold to lower manifold.
- Position Exhaust Gas Recirculation (EGR) and injector wiring harness out of the way.
10. Upper manifold assembly and gasket.
- Discard gasket.
CAUTION: Use care in cleaning old gasket material from machined aluminum surfaces as sharp tools may damage sealing surfaces.
Clean
- Gasket cleaning surfaces
NOTE: The upper manifold contains integral sealed throttle shaft bearings and parts that should not be cleaned or soaked in a cold immersion cleaner. Use carburetor choke cleaner and a shop towel or nonmetallic parts cleaning brush to remove any carbon deposits.
- The upper manifold assembly contains the TP sensor, IAC valve, and sealed throttle shaft bearings which should not be subjected to a strong solvent or cleaner bath. A chemical reaction will cause the parts containing rubber to swell, harden or distort, and the cleaner will also wash away the sealed bearing grease, or weaken its lubrication properties.
- The lower manifold assembly contains four bottom feed MFI fuel injectors and a pressure regulator assembly. Do Not place these parts in a strong solvent or cleaner bath. After removal of the injector retaining bracket, regulator and injectors, the lower manifold assembly may be cleaned in a cold immersion cleaner, such as GM X-55 or equivalent.
Inspect
- Replacement upper manifold for items that are to be transferred from unit removed from engine.
DISASSEMBLE
- Upper manifold following component repair procedures.
- Power brake vacuum fitting.
ASSEMBLE
- Replacement upper manifold with transferred pants following component repair procedures.
- Power brake vacuum fitting coated with appropriate thread-locking material.
Thread-Locking Material
The hardware used to attach the upper manifold Throttle Position (TP) sensor, Idle Air Control (IAC) valve, MAP sensor, power brake fitting, and the lower manifold pressure regulator and injector bracket attaching hardware are coated with thread-locking adhesive. If any these parts are removed for service, inspect the attaching screw threads. There should be enough thread-locking material (adhesive or compound) on the threads to insure proper relocking. If not, clean the threads and apply Loctite 262, or equivalent, to the threads before reassembly. Replacement screws are included in the service screw assortment package. New attaching hardware is included in the service packages.
Tighten
- Power brake vacuum fitting to 13.0 Nm (115 lb. in.).
INSTALL OR CONNECT
- Position EGR valve injector so that the port faces directly toward the throttle bore.
1. New upper manifold gasket.
2. Upper manifold assembly.
- Reposition EGR and injector wiring harness.
3. Upper manifold attaching bolts/studs.
Tighten
- Upper manifold bolts/studs to 30.0 Nm (22 lb. ft.).
4. Accelerator cable bracket with attaching bolt/nuts.
Tighten
- Accelerator cable bracket nut to 30 Nm (22 lb. ft.).
- Accelerator cable bracket bolts to 25 Nm (18 lb. ft.).
5. Accelerator, cruise, and transmission control cables,
6. Splash shield to accelerator bracket.
7. Electrical connectors to MAP sensor, TP sensor, IAC valve, and EGR vacuum solenoid.
8. Vacuum hose harness to top of air inlet.
9. Connect crankcase ventilation valve and power brake vacuum hoses to vacuum tubes at upper manifold.
10. Negative battery cable.
Inspect
- Turn ignition switch to the "ON" position for two seconds, then turn to the "OFF" position for ten seconds. Again turn to the "ON" position, and check for fuel leaks.
11. Air intake duct.