everyone says pcv elbow.. is that the elbow that comes right off the pcv?? i pulled the pcv tube off the truck and inspected it.. the elbow doesnt LOOKED cracked.. and the rubber fitting that goes on the back of the intake doesnt look rotted .. if u bend it it shows some signs of age.. but no visible rot or wear on this tube..

 

no its at the back of the intake. Kind of hard to get to.. follow the line from the pvc.

 

While it's extremely common failure and accounts for an estimated 90% of p0171/P0174 complaints, it's not the only possible cause.

Next most common would be a leak in the intake air tube between the MAF and the throttle body or else a dirty MAF sensor, especially if using an oiled air filter. There are still more reasons, but these cover most failures.

 

ive pulled that whole tube off it wasnt too hard to remove.. there really isnt an elbow just a rubber fitting that goes to the back of the intake..

im thinking my maf maybe bad, ive cleaned it numerous times.. thinking the egr passage maybe clogged or plugged up or w/e

 

could be a fuel issue. Partally clogged injectors can cause this code. A vacuum leak else where. Exhaust leaks are known to cause it to.

 

Which motor are we talking about. I've got a 4.2 with the heated PCV that connects directly to the T/B, mine was leaking there. The O-ring goes bad and you have to buy the whole PCV from Ford ar about 35 bucks. I looked in the help sectipn at Autozone and they have some O-rings for (Ihate to say it) GM distributors that might work, just be sure to use the oil resistant ones.
Btw I replaced my PCV but it didn't help and the hoses are good. I also cannot find the legendary elbow at the back of my motor,I think maybe there is a differen't system for the 4.2's.
Just trying to see if I'm on the same page as everyone else because the next step seems to be upper and lower plenum gaskets-not looking foward to that!

 

wow.. numerous problems huh.. well in trying to diagnoise this i noticed that im starting to get worse mpg.. and she seems to run better cold then when warmed up .. does that mean anything as far as fuel delivery or vacuum leaks..its a 4.6

 

Have you done the MAF cleaning? That helps alot.
If it is a vac leak it would bother it all the time, since yours is worse when it's warm you might try checking the EGR/DPFE stuff or maybe the IAC. That's just my un-educated guess though.
Keep posting as you find out stuff, cuz I could use the help too!!!

 

Where the tube is weathered and sort of scaling is the bad. Specially if your not running a Motorcraft PCV valve. Aftermarket replacements are totally bad and way to restrictive compared to the motorcraft valve, only run the Motorcraft valves or you can bring your engine to an early grave. Running lean is very unhealthy, she can't breath and chokes down oil instead!! Until you develop holes for the unmetered, which happens eventually.

Bad restrictive non OEM replacement valves expand your PCV system when running which develop pin holes you can't see in it's normal state. Thus, you get the lean DTC's and have a sick engine.

Thought you might want to know.

 

i have pulled the iac off and let it sit in a mineral spirits bath for a couple hours.. it cleaned it up a lil bit.. im not really sure if u can really even clean them or if you just supposed to replace it.. i do however want to get around to either cleaning and inspecting the egr or just replacing it.. what is the DPFE??

yes that thought has crossed my ming.. i honestly do not recall if i bought a motorcraft replacement or not.. i suppose i should replace it regardless..

 

IAC's dont clean up well. New ones at autozone are like $49 I have 2 AZ IAC's and have had no issues with them.

 

i got the same codes coming up first i took off my gotts intake that worked for about 2 weeks then my vo-tec teacher said it is a back pressure problem due to cutting my muffler
so who knows

 

- They must have been desperate for instructors.

 

guys i have been putting up with these same exact codes for a bout 4 months now and have already did everything that yall have plus some believe it or not..... trust me when i say this it WILL pay off..... take it to the local shop that is nearest you and have them take a look at it.... throwing parts at it like i have done will NOT solve the problem...... im still having trouble becuase it can literally be about 20 different things... i want to save yalls time and money so trust me when i say to take it to someone that can take an educated look at the problem
CJ

 

Hate to burst your bubble (not really), but the educated have confirmed it's much easier than you think and I agree. However, you do have to go thru the steps.

Ford says MAF first, but the PCV system is and has been the more common problem. So the list SHOULD go like this IMO.

1. PCV system.
2. MAF.
3. Fuel system - all.
4. All vac lines - vac test.
5. Intake manifold gaskets.

It has always been one of the 5, UNLESS your missing on one of the eight.