Important: This engine uses a sequential multiport fuel injection system. Connect the injector wiring harness connectors to their appropriate fuel injector or exhaust emissions and engine performance may be seriously affected.

1. Disconnect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
2. Disconnect the wiring harness connection from the intake air temperature (IAT) sensor in the throttle body air inlet duct. Refer Intake Air Temperature Sensor Replacement in Engine Controls - 3.4L.
3. Disconnect the throttle body air inlet duct.
4. Drain the engine coolant from the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
5. Remove the accelerator control and cruise control cables with bracket from the throttle body. Refer to Accelerator Control Cable Replacement in Engine Controls - 3.4L.
6. Remove the throttle body. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.4L.
7. Disconnect the wiring harness attachment clips.

•	Camshaft position (CMP) sensor wiring harness

•	Left spark plug wire harness

8. Disconnect the thermostat bypass pipe coolant hoses from the throttle body.
9. Remove the rear generator brace. Refer to Generator Brace Replacement in Engine Electrical.



10. Remove the following components:

10.1.

Vacuum lines at the upper intake manifold

10.2.

MAP sensor

10.3.

EGR valve

10.4.

Spark plug wires

10.5.

Ignition control module

10.6.

Upper intake manifold

10.7.

Upper intake manifold gaskets

11. Clean the seal surfaces on the manifold with degreaser.

1. Install the throttle body. Refer to Throttle Body Assembly Replacement in Engine Controls - 3.4L.



2. Install the upper intake manifold gaskets.
3. Apply threadlock GM P/N 12345382 or equivalent to the threads of the intake manifold bolts.
4. Install the upper intake manifold.

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 upper intake manifold bolts and studs.

Tighten
Tighten the upper intake manifold bolts and studs to 25 N·m (18 lb ft).

6. Install the following components:

6.1.	Upper intake manifold gaskets

6.2.	Upper intake manifold

6.3.	Ignition control module

6.4.	Spark plug wires

6.5.

EGR valve

6.6.	MAP sensor

6.7.	Vacuum lines at the upper intake manifold

7. Install the rear generator brace. Refer to Generator Brace Replacement in Engine Electrical.
8. Connect the thermostat bypass pipe coolant hoses to the throttle body.
9. Connect the wiring harness connectors to the throttle body.

•	Throttle position (TP) sensor

•	Idle air control (IAC) valve

10. Install the accelerator control and cruise control cables with bracket to the throttle body. Refer to Accelerator Control Cable Replacement in Engine Controls - 3.4L.
11. Fill the cooling system with engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.
12. Install the throttle body air inlet duct.
13. Connect the wiring harness connection to the intake air temperature (IAT) sensor in the throttle body air inlet duct. Refer to Intake Air Temperature Sensor Replacement in Engine Controls - 3.4L.
14. Connect the vacuum hose connection to the throttle body air inlet duct.
15. Connect the battery ground (negative) cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.