To replace the upper intake manifold (plenum) on 2001 and earlier models, first relieve the fuel pressure, disconnect the negative battery cable, remove the air intake duct, and take out the ignition coils while labeling and disconnecting the hoses and electrical connectors attached to the plenum and throttle body. Next, remove the EGR guide tube and the upper manifold support brackets from the rear of the upper plenum, noting that the bolts are difficult to access. Loosen the upper intake manifold bolts in reverse order of the tightening sequence and remove the upper plenum with the throttle body attached. For installation, clean the mounting surfaces of the intake manifold and upper plenum with lacquer thinner, install a new gasket with the mark facing forward, and tighten the bolts in the recommended sequence. For 2002 and later models, begin by removing the cowl panel and windshield wiper assembly, then the decorative cover from the engine, and the air cleaner housing. Drain the cooling system and disconnect the coolant hoses from the upper intake manifold. Label and disconnect the vacuum hoses and electrical connectors, free the wiring harnesses and hoses from retainers, unscrew the nuts securing the EGR tube to the lower manifold, and unbolt the canister purge and variable air intake solenoids along with the vacuum tank. Remove the upper manifold's support bracket and the five bolts securing the upper manifold to the lower manifold in a criss-cross pattern, lifting the upper manifold off afterward. For the lower intake manifold, detach any remaining hoses that would interfere with its removal, then remove the fuel rail and injectors. Loosen the manifold mounting bolts/nuts in 1/4-turn increments until they can be removed by hand in reverse order of the tightening sequence. If the manifold is stuck to the cylinder heads, use caution to avoid damaging the gasket sealing surfaces. Carefully scrape off old gasket material and sealant, clean the mating surfaces, install new gaskets, position the lower manifold on the engine, and ensure alignment over the studs in the cylinder heads before installing the nuts. Finally, tighten the nuts/bolts following the recommended sequence and check for fuel, vacuum, and coolant leaks after running the engine.
Posted by NissanPartsDeal Specialist 
