I just replaced my upper and lower intake manifold gaskets, fuel injector o-rings, replaced some vacuum lines and replaced plugs,wires, oil change, and MAF sensor all within this year. Yet those two pesky codes keep returning.
I got a live data code reader and the freeze frame data shows the code pulling at 1408 rpm with the engine at 88 degrees centigrade. My fuel trims: LTFT both at 24.2% and my short terms at bank one 21.5 and bank two 19.5

Does anyone have any idea what's going on. I'm stumped and running out of cash.

 

http://engine-codes.com/p0171_ford.html & http://engine-codes.com/p0174_ford.html. It looks overwhelming but, usually its a vacuum leak some where. Check all the vacuum lines and gas cap for leaks, cracks, melting.,.....etc.

 

I found that my front hubs were leaking vacuum. I replaced the front bearings, the right side was ready to fall apart but you couldn't feel it driving it. I replaced the factory vacuum hubs with manual locking hubs and blocked the vacuum lines to the hubs. After doing this my check engine light quit coming on. I also installed a vacuum gauge to keep track of the vacuum of the engine, it idles at 24psi of vacuum. Problem fixed

 

Darrell,
where did you get the parts for this? I have the same two troublesome codes and had a garage do a smoke test and found nothing

 

I got all the parts for the front end off E- bay

 

Thank you

 

Did you replace this elbow?

I replaced the whole tube with both the front and back elbows, code went bye-bye.

 

I have not yet, so far just did a tune up and had a smoke test done, no leaks on smoke test

 

Pulled fuel filter and looked like chocolate milk coming out. Hope this fixed the issue

 

Ewww.

 

I don't think the previous owner did anything but gas and go