Removal

• 1). Pop the hood of your Mazda Navajo and start with a cool engine. Remove the negative battery cable by loosening the cable clamp with a wrench. Set the cable away from the battery posts.
  
  
• 2). Locate the fuel pressure relief port at the front passenger side of the engine on the intake manifold. The port has a small black cap on it, similar to the one on your tire valve stems. Attach a fuel pressure gauge to the port by screwing it on by hand. Put the gauge drain hose into a gas can and open the pressure relief valve on the gauge. Let the fuel go into the can then close the valve. Remove the gauge from the engine and replace the black cap on the port.
  
  
• 3). Follow the air intake ducting from the air cleaner housing to the throttle body. At the throttle body, loosen the duct clamp with a screwdriver and remove the duct.
  
  
• 4). Remove any engine covers around the accelerator cable with a ratchet and socket. Use the same ratchet to remove the bolts holding the accelerator cable bracket. Pull the cable end off of the throttle body by hand.
  
  
• 5). Locate all vacuum hoses and electrical connectors attached to the throttle body and intake manifold. (The intake manifold is what the throttle body is attached to). Use tape and a felt pen to mark the placement of these items, before you remove them, for later reinstallation.
  
  
• 6). Disconnect all marked items. Pull off the hoses by hand. Squeeze the electrical connectors then pull them apart. Remove the fuel injector electrical connectors in the same manner.
  
  
• 7). Remove the fuel lines from the fuel rail. The fuel rail is the assembly that the injectors are connected to. Follow the rail to the back of the engine to see the fuel lines. Remove them with a wrench. Clean up any fuel that may dribble out.
  
  
• 8). Use a ratchet to remove the mounting bolts for the ignition coil. This is a square, black box on the intake manifold with electrical wires coming out of it. Move the coil out of the way.
  
  
• 9). Remove the retaining nuts for the top half of the intake manifold. Use a ratchet and socket to remove them then lift the top half of the manifold out of the engine. Throw away the gasket.
  
  
• 10
  
  Use a ratchet and socket to remove the retaining bolts for the valve covers on each side of the engine. Throw away the valve cover gaskets.
  
  
• 11
  
  Loosen and remove the retaining bolts for the lower manifold with a ratchet and socket. Pull the lower manifold from the engine and throw away this gasket as well. Stuff some rags into any intake openings to keep objects from falling in and causing damage.
  
  

Installation

• 1). Apply a high-temperature gasket sealant to the mating surfaces of the lower intake manifold and engine block. Position the new gasket onto the engine block and set the new manifold down on top of it.
  
  
• 2). Tighten the retaining bolts for the lower manifold by hand. Tighten each bolt with a torque wrench to between 15 and 18 foot-pounds The tightening pattern starts with the outside, opposite corner bolts. Once all four outside bolts are tight, perform the same pattern as you work your way inward.
  
  
• 3). Apply gasket sealer to the valve cover mating surfaces. Position new valve cover gaskets onto the engine and install the valve covers. Tighten the bolts to between 3 and 5 foot-pounds with the torque wrench. Wait a few minutes then double-check the torque.
  
  
• 4). Install the new upper manifold gasket and the manifold to between 15 and 18 foot-pounds with the torque wrench. Reattach the ignition coil and tighten the bolts with the ratchet and socket. Also reconnect the fuel rail lines and tighten them with the wrench.
  
  
• 5). Reattach all marked items to the manifolds and throttle body. Be sure all electrical connectors are fully pushed together, including the fuel injector connectors.
  
  
• 6). Reconnect the accelerator cable and reattach the bracket. Tighten the bolts on the bracket with the wrench. Be sure to install any covers over the cable you may have removed. Secure the cover bolts with the ratchet and socket.
  
  
• 7). Reattach the air duct to the throttle body opening. Tighten the clamp with the screwdriver.
  
  
• 8). Reconnect the negative battery cable to the battery post and tighten the clamp with the wrench. Crank the engine and check for any leaks.