PO171 and po174 2000 4.2 4wd
 

I recently bought a 2000 F150 4wd with 4.2 and I keep getting the po171 and po174 code. My code reader does live data and fuel trims but I don’t understand fuel trims.

I’ve cleaned throttle body . Mass air sensor, new air filter and new plugs.

Do I have a dpfe? If where?

Look for vacuum leaks.

Chris Fix has a video showing how to check for vacuum leaks using a shop vacuum to blow up the tail pipe and then spray soapy water on the suspected vacuum leak locations to see if there are bubbles.
If you can understand the fuel trim readings, usually they are normal when the engine is revved if it is caused by a vacuum leak.

I saw the water video but didn’t know about vacuum cleaner in exhaust. I don’t have a smoke machine.

A smoke machine would be optimal, but not necessary. Try the shop vac and soap method first.

I hooked fuel pressure tester to fuel rail a few minutes after moving truck to shade. It was 0 with engine off. I turn key on engine off it jumps to 35 then quickly to about 31.I start engine it drops to about 28. Seems it drops to about 25 psi at 3500 rpm’s.

At 3pm engine off about 29 psi

302 pm at 32 psi engine off. I changed fuel filter a few months when I bought it.

15 minutes still at about 32 psi

Within specs, barely. Specs are 28 to 40. With it idling, pull the vacuum hose off the fuel pressure regulator, pressure should rise at least 5 psi. This is what the DPFE looks like:

https://cimg8.ibsrv.net/gimg/www.f15...80d6094c14.jpg

po171 and po174 code cause?

Pull hose off Dpfe or regulator? I know dp is delta pressure but thought there a regulator as well.

DPFE is for the EGR, has nothing to do with the fuel pressure regulator. The FPR is on the rail and looks like this:

https://cimg4.ibsrv.net/gimg/www.f15...d57ab786af.jpg

If you want me to remove hose from regulator why post pics of dpfe??this is now confusing.