I have a 2002 Passport and am getting PO171 and PO174 lean codes. I had my intake gasket replaced about a year and a half ago at a dealer and believe it is leaking again. How big a deal is this to replace myself? Any help is greatly appreciated.

This post has been edited by JRUT: Mar 13 2008, 08:03 AM

It is not difficult to change an intake manifold gasket but it will take you several hours. First you must disconnect the battery. Drain the coolant from the radiator and remove the engine cover if equipped. If not remove the air cleaner tube from the throttle body. You will need to remove the top radiator hose from the engine. It may be a good idea to replace the thermostat so disconnect the hose where it connects to the top of the manifold. Now you will need to remove such items as the coils, spark plug wires. It is best to number them so you can get them back on the right plug. Now you will need to remove the associated hardware that will prevent removal. Take the belt off, remove the alternator if it is attached to the manifold either directly or by a bracket. Remove the fuel line from the fuel rail after you release the fuel pressure. Be very careful not to damage the rails or the threads when you remove the fuel line. If there are any other hoses or lines connected to the manifold you will need to remove them as well. Disconnect the throttle cable, kick down and other associated connections to the throttle body. Now gently remove the wires from the injectors, there may be a clip that must be removed. Mark each one as to the number and location. Use a piece of tape to mark them.
Once everything is loose take a socket of the appropriate size and loosen the manifold bolts. Start in the center and work your way in a cris-cross pattern going toward the outside of the engine. Once everything is loose remove the bolts and place them in a bag or tray so you don't lose them.
Now, gently pry the manifold loose from the front of the engine. Use a screw driver and gently pry until the manifold comes loose. Once loose remove from the engine and place aside. Place paper towels in each port and lay a shop towel or two in the lifter galley. This will prevent any gasket or other material from dropping in the ports or galley that could damage the engine. Scrape the gasket surface with a gasket scraper to remove the old gasket. Wipe the surfaces clean and get ready to put everything back together.
Remove the towels being careful not to drop anything in the ports and make absolutely sure you do not forget to remove one! Place the new gaskets in place, there should be retainers with the set or locating pins on the heads. At the end of the manifold where it contacts the block there will be an area that has some type of silicone sealant. Remove the old sealant and replace it with a sensor safe silicone material. Most good gasket kits come with this in a tube. Put a healthy bead, not too much and allow for a curing time of about 30 minutes. Replace the manifold by placing it straight down. Don't twist it or move it excessively as you may dislocate the gaskets and cause a leak.
Replace the bolts and torque to specification in a pattern designated by the manufacturer. Hook up everything you disconnected and fill the radiator with coolant. Reconnect the battery and you should be able to start the car. Run it up to operating temperature and check for leaks.
I told you this will take time. I would also invest in a Chiltons manual before attempting to do this job.
If the car is a GTP forget the whole thing if you are a novice and have her take it to a repair shop. Good Luck!