Trouble code P0171 & P0174 on a 2003 F-150 with 4.2L V6. I have cleaned the MAF, changed the fuel filter, looked for vacuum leaks, checked for vacuum leaks with the MAF cleaner (flammable), checked every thread on this forum, had the check engine light reset several times. The truck runs fine, just idles a little high when I first start it (1000 - 1500 rpms). Once it warms up it runs like a champ and idles at 600-750 rpms. When I have the code reset, it will stay off until the next cold front moves in (32 F or colder). Any suggestions would be a great help. I have also removed and cleaned the IAC (does anybody know the correct torque for those two bolts????)

 

Welcome to the forum.

Remove and inspect the PCV hose elbows. They are known to get soft and either crack or suck shut.
The IAC bolts, I just snug them up, maybe 1/4 turn after the bolt stops turning by hand. They don't need to be overly tight.

 

That's another problem - I can't even find the PCV. Theres a hose that goes into the drivers side valve cover by the oil filler tube, but no PCV or vacuum. Theres also a hose going into the valve cover on the passenger side next to the firewall. This one does have a vacuum, but no PCV. Am I looking in the wrong place or just looking at the wrong thing. Unfortunatly I can not find a book for this particular year model. I have also tried looking for the PCV at autozone to make sure I was looking at the right thing but they said it was a dealer item.

 

On the IAC bolts, I torqued them to 15 ft lbs. If anybody has a better setting please let me know. Thanks.

 

It sounds like you need the revised intake isolator bolts and new port gaskets. These tend to set a lean code that freeze frame shows was set at cold engine temp and cold ambient temps seem to exasperate the concern. There is a tsb out for this concern. The pcv valve is in the intake held by 2 torx screws. The elbow of the hose leading from it to the rt valve cover tends to rot out, if replacing install the complete hose assembly and replace the valve. If you need the part #s or the tsb , you can pm me and I will look it up.

 

any Idea how much this is going to cost? and can it be done by an amatuer?

 

It should be relatively inexpensive for parts, but we usually get 3hrs labor at $85 per hour at the dealer. This is something you can do yourself though, Remove the upper intake hat by removing the vacuum lines, throtle cable etc. and removing all the 10mm bolts that hold it on and then remove the actual upperintake by removing the 8 8mm bolts securing it. These bolts do not come out until after the intake is off and you knock them out to install the new ones.

 

Sounds easy (does it really take 3 hrs????). What about the port gaskets?

 

Replaced the intake bolts and gaskets. Had the CEL reset. So far, everything looks and sounds good. Truck still idles high at start up. Won't know for sure if its fixed until the next cold front (I live in south Louisiana, so I may have to wait until next November). It wasn't as easy as I thought it would be. I highly recommend a deep well socket to tighten the bolts on the back of the intake plenum (they come off pretty easy, but tightening is another story). Also make sure you have the correct torque wrench before starting the job.