To begin the removal process, relieve the fuel system pressure and disconnect the cable from the negative terminal of the battery. Next, remove the engine cover. For 2006 and earlier models, disconnect the accelerator and cruise control cables. Proceed by removing the air inlet tube and air filter housing, then disconnect the PCV hose and the brake booster hose. Disconnect the ground strap, electrical connectors, and vacuum lines from the upper intake manifold, labeling each connector for correct reassembly, and pull the wiring harnesses aside. For 2006 and earlier models, clamp off the coolant lines to the throttle body and disconnect them; for 2007 and later models, drain the engine coolant and disconnect the heater hoses from the heater core tubes at the firewall. Remove the upper intake manifold support brackets and disconnect the electrical connectors and hoses to the throttle body, taking care to clamp off the coolant hoses before detaching them to prevent spillage. Disconnect the electrical connectors to the various sensors and move the harness out of the way, then remove the bolts mounting the upper intake manifold to the lower intake manifold. Drain the cooling system and disconnect the electrical connectors from the fuel injectors, also detaching the fuel line from the fuel rail while pulling the wiring harness aside. The intake manifold can be removed with the injectors and fuel rails in place or separately, depending on the work required. Disconnect any remaining components from the lower manifold, then remove the mounting bolts in reverse order of tightening, detaching the lower intake manifold from the engine without prying between the gasket mating surfaces to avoid damage. Check the manifold's surface with a precision straightedge and replace it if excessively deformed. For installation, use a scraper to remove old gasket material and sealant from the lower intake manifold and cylinder heads, cleaning the mating surfaces with brake system cleaner. Install new gaskets and position the lower intake manifold on the engine, ensuring the gaskets haven't shifted before installing and tightening the bolts in three or four equal steps to the specified torque. Install a new gasket between the lower and upper intake manifolds, place the upper intake manifold on the lower intake manifold, and tighten the bolts gradually to the specified torque. Finally, refill the cooling system, run the engine, and check for fuel, vacuum, and coolant leaks.
