nst1793

Have a 02 screw lariat 4x4 getting lean codes.. Checked vacuum leaks checked pcv system cleaned throttle body egr ports egr iac maf sensors has relatively fresh tune up changed fuel filter all the normal stuff to cause this... Kicks the codes I reset them and seems to run good once in a while it will idle 900 rpm then once in a while idle what I think would be norm about 750ish no light on during the idle issue then the next day or a while the light may come back on same codes no drivability issues runs good other than a slightly elevated idle from time to time so I'm at maf going out? Or iac would either one cause these codes any help would be appreciated! Thanks in advance

Marc D

Among many things associated with these codes, there are known vacuum leaks on the upper and lower intake plenums. I just corrected my 2000 4.2 V6 a year ago by putting in new gaskets. I ran the same codes you're getting and made the same repairs as you have before sucking it up and finally pulling the intake manifold. It took me about 8 hours (over 3 days) and $350 w/all Ford factory parts.

nst1793

Yup that is going to be my last resort I did do a smoke test and seen nothing leaking smoke i have the plastic intake upper manifold and aluminum in the bottom half that bolts to the heads if course would you think just the upper or take it down all the way to the heads? Really don't want to do it but hate looking at the light I reset it two days ago and it's not came on since but I also put new pcv tubing all the way to the back of manifold and new pcv valve hoping this would be it no light yet and seems to be idling wich I would consider normal 700-750ish but it's interment on the idle sometimes it idles 900 so that's kinda why I was considering it being a sensor I'm just stumped on this one this is the first 5.4 I've had not real familiar with them

hounddog1

I had the same codes,and it turned out to be the upper,and lower intake manifold gaskets were cracked.

nst1793

How difficult was it to do the gaskets? I looked mine over and doesn't look too bad but thought intake was all one piece witch is plastic

Marc D

Making mechanical repairs like this is not difficult if you are mechanically inclined and you have the correct tools. I used several You Tube Videos to help with the sequence of disassembly and reassembly paying attention to details such as where to seal the ends of the manifold properly. Good luck

nst1793

Ok yeah done several intakes before just not real familiar with the ford triton engines looks to be all plastic on the intake am considering just buyin the doorman kit that comes withy the new intake and everything you need but I can hear a vacuum leak towards passenger side haven't confirmed 100% it is the intake yet so I may investigate a little further just haven't had a lot if time lately and pretty cold out right now where I am at and no heat in garage

papa tiger

Stanley has a nice ceramic electric heater. Run The vehicle until it is nice and warmed up, shut it off, shut the garage tight with bottom of door sealed and turn on the electric heater, with the vehicle warm it will help a lot as it cools down the garage will warm up. Mechanics gloves and UR good.

nst1793

Yeah had a nice salamander that run off kerosene but it took a dive!

nst1793

Ok so I took apart my f150 with the 5.4 2v and have the intake manifold ready to reinstall with new felpro gaskets along with new orings for injectors two questions
1. The tube that runs under where the intake sits how does it come apart to replace the orings? There's no bolts that I can see it's just a straight metal tube doesn't seem to be leaking should I leave well enough alone if now how does it come apart!?
2. Everything as far as I can tell the factory intake manifold looks to the eye good mating surfaces and everything as far as my eye can tell anyway would it be safe to say it's okay to reuse with my new gaskets or should I buy the new dorman set? Amazon for about $160-180 local around a killer $230 or so...

Any input is appreciated