GM 12555840
Intake Plenum

Replacing the Intake Manifold; take off the 2 nuts of the Intake Manifold sight shield and remove sight shield from engine. Remove coil module connectors from coil modules in the camshaft covers, pcv dirty air tube, pcv fresh air tube, fuel regulator vacuum tube, and vacuum tubes from air solenoid. Then unplug the fuel inlet and return quick-connect couplings at the Fuel Rail, remove the Fuel Rail bracket retaining nut at the rear lift bracket and remove the 2 pushnuts attached to the engine coolant heater wire if so equipped, putting it out of the way. Remove the eight electrical connectors from the eight fuel injectors by carefully sliding the surge tank pipe away from the Fuel Rail studs. Now remove the four bolts that hold the Fuel Rail to the Intake Manifold. Remove the whole Fuel Rail and injector assembly from the Intake Manifold, loosen the plenum duct clamp located at the rear end of the Intake Manifold, peel off 10 bolting used in fastening the Intake Manifold to the cylinder heads. Lift up the Intake Manifold from the front with an upward movement, and clean and inspect it. For installation, lubricate lightly inside edge of rubber plenum duct, clean the Cylinder Head or Intake Manifold before installation onto new gaskets off the Intake Manifold. Make sure that the PCV Valve Hose is securely connected to the fitting of the front Intake Manifold before installing it. Put the rear of the Intake Manifold into the plenum duct, and position the front on top of the cylinder heads, subsequently loosely fixing the Intake Manifold to the cylinder heads using the 10 bolts, tightening them in sequence to 10 nm. Make sure the plenum duct is secured completely on the back of Intake Manifold; tighten the plenum duct clamp to 2.25nm. Lubricate intake manhattan Fuel Injector bores with light mineral oil gm p/n 9981704 engine oil, clean engine oil or equivalent. Install entire Fuel Rail and injector assembly into the Intake Manifold without being forced into the injectors. Put on the 4 bolts that fasten the Fuel Rail to the Intake Manifold and secure them using 10 nm. Connect the 8 electrical connectors to the fuel injectors; connect the surge tank pipe to the Fuel Rail studs; connect the engine coolant heater wire to the Fuel Rail studs if so equipped. Fit and tighten the 2 pushnuts, fuel rail bracket retaining nut to the rear lift bracket and tighten to 10 nm. Mount the quick connect fittings onto the Fuel Rail, vapor lines to air solenoid, fuel regulator vacuum tube, pcv fresh air tube, pcv dirty air tube, coil module connectors to the coil modules in the camshaft cases. To check for fuel leaks, activate ignition by turning it to on for 2 seconds, off for 10 seconds, and on. Lastly, set up your Intake Manifold sight shield to the engine and thread in the 2 sight shield nuts to 3 nm.

Begin by removing the two sight shield retaining nuts and pulling off the shield from the engine location. Remove coil module connectors from the coil modules located within the camshaft covers and detach the PCV Valve from the camshaft cover and the pcv fresh air tube from the camshaft cover as well as the vacuum tube from both the air solenoid and the fuel regulator vacuum tube. The service process begins with disconnecting connectors from both fuel inlet and return quick-connect fittings at the Fuel Rail and the Fuel Rail bracket retaining nut at the rear lift bracket and the two pushnuts securing the engine coolant heater wire. The generator coolant hose/surge tank pipe should be carefully moved off the Fuel Rail studs before completing the removal of the eight electrical connectors connecting to the eight fuel injectors. To detach the Fuel Rail from the Intake Manifold you must remove the four bolts followed by lifting the Fuel Rail and all of its connected injectors off the manifold. Climb under the car to the rear of the Intake Manifold and loosen the plenum duct clamp before removing the ten bolts that fasten the Intake Manifold to the cylinder heads. Afterward you can lift the Intake Manifold by pulling upward on the front end. Check and inspect your Intake Manifold for any damage or wear. Installing this component requires light lubrication of the rubber plenum duct's inner edge followed by debris removal from the Cylinder Head or Intake Manifold so new gaskets can be fitted to the Intake Manifold. Position the Intake Manifold by inserting the rear section into the plenum duct first before guiding down the front towards the cylinder heads. Install the PCV Valve hose securely to the front fitting of the Intake Manifold prior to this step. Begin by attaching ten bolts between the Intake Manifold and cylinder heads starting from the center then move toward 10 nm (89 inch lbs.). The plenum duct must achieve full contact with the Intake Manifold rearsection before performing clamp tightening to 2.25 nm (20 inch lbs.). Tightening forces on the injectors must be avoided to maintain o-ring seals intact so the complete Fuel Rail and injector system needs to be inserted simultaneously into the Intake Manifold. Tighten all four bolts securing the Fuel Rail onto the Intake Manifold to 4 nm (35 inch lbs.). Thoroughly connect all eight electrical connectors to their matching fuel injectors before placing the generator coolant hose/surge tank pipe and engine coolant heater wire onto appropriate Fuel Rail studs. Then fasten both pushnuts using a wrench. Put the Fuel Rail bracket retaining nut on the rear lift bracket before tightening it to 4 nm (35 inch lbs.). Assemble quick connect fittings to the Fuel Rail before you attach vacuum tubes to the air solenoid and fuel regulator vacuum tube and pcv fresh air tube to the camshaft cover and PCV Valve to the camshaft cover and coil module connectors to coil modules within the camshaft covers. The inspection for fuel leaks should begin by turning the ignition switch on for 2 seconds followed by a 10-second off period before a return to the on position. Install the Intake Manifold sight shield onto the engine before tightening the two Intake Manifold sight shield nuts to 3 nm (27 inch lbs.).

Remove the 2 pushnuts securing the engine coolant heater wire and set it aside.

Disconnect the fuel regulator vacuum tube and the vacuum tubes from the AIR solenoid.

Lubricate the intake manifold fuel injector bores with light mineral oil or clean engine oil.

Remove the 2 push nuts securing the engine coolant heater wire and set it aside.

Disconnect the fuel inlet and return quick-connect fittings at the fuel rail, then remove the fuel rail bracket retaining nut at the rear lift bracket.

Connect the vacuum tubes to the AIR solenoid, the fuel regulator vacuum tube, the PCV fresh air tube, and the PCV dirty air tube to the camshaft cover, followed by the coil harness connectors.

Position the intake manifold sight shield onto the engine and install the 2 intake manifold sight shield nuts, tightening them to 3 Nm (27 inch lbs.).