Q: How to remove and install the intake manifold in four cylinder engine on Mercury Mariner?
A: For 2008 and earlier models, begin by relieving the fuel system pressure and disconnecting the cable from the negative battery terminal. Remove the air intake hose, then disconnect the accelerator cable and cruise control cable from the throttle lever arm. Next, remove the fuel rail, fuel pressure regulator, and fuel injectors as a single assembly, followed by the breather hose and PCV valve from the intake manifold. Disconnect the ignition wires and the ignition coil harness connector, then disconnect the vacuum lines from the intake manifold, labeling them for reassembly. Proceed to disconnect the PCM harness connector and the cylinder head temperature sensor connector, detaching the harness from the clip. Remove the alternator and the EGR valve, and if replacing or servicing the intake manifold, remove the throttle body; otherwise, it can remain attached if only servicing the cylinder head. Remove the intake manifold support bracket, fasteners, and washers, then take out the intake manifold and gasket. Inspect the intake manifold mating surface for warpage using a straightedge and feeler gauge, and resurface or replace as necessary. For installation, use a new manifold gasket, install the intake manifold, and tighten the bolts and nuts in stages from the center out. Reconnect the battery, allowing the Powertrain Control Module to relearn its idle and fuel trim strategy. For 2009 and later models, start by relieving the fuel system pressure and disconnecting the negative battery terminal. Remove the fuel rail, disconnect the vacuum line and vapor return hose from the intake manifold, and move aside any interfering wiring harnesses. Detach the pin retainer from the heater hose, disconnect the air intake duct from the throttle body, and remove the bottom bolt from the intake manifold before taking out the six main intake manifold bolts. Move the manifold aside to access and detach the PCV vent tube and EGR tube, then remove the intake manifold and its gaskets. Inspect the intake manifold gaskets and replace any that are damaged, then reinstall by reversing the removal steps and tightening all fasteners to the specified torque values.