Ok, I have searched this for some time but cant really come to a conclusive decision. I throw the p0174 code about once a month. I just figured out today that the O'riley scanner reads FF data as well and this is what it had

Po174
LTFT Bank 1 = 9.3%
STFT Bank 1 = 5.4%
LTFT Bank 2 = 8.5%
STFT Bank 2 = -0.7%
Engine idle was 850 rpm
Temp was 170F

What do you guys think it is? I have looked of the PCV tube (i think) and I dont see any cracks. Is it the tube that runs from the PCV valve (center of the driver side valve cover) straight up to the throttle body? With times the way they are, I would rather not just start replacing parts (O2 sensors) to find it if I dont need to. I am kind of crossing my fingers that it is... they are somewhat cheap

BTW, 2001 expedition 5.4. Seems to run fine when I am in it. Its the wifes ride.

Thanks for any help

 

It isn't O2 sensors as they rarely cause this type of code..

Those are some pretty low numbers to be setting a "lean" fault code. I'd expect the sum of the short and long term trims to exceed 30% (or more) in order to set the MIL.

For now, since the data are incomplete and suspect, I'd reset the PCM (pull the KAM fuse for 10 minutes). Then drive it until the MIL is set again. Record the COMPLETE FF data including Load % and VSS and try again.

The PCV valve on my 97 is located on the passenger side valve cover (your 01 may be different). Its hose snakes around to the firewall side of the throttle body where it connects to a port via the infamous 90 degree elbow.

 

Ditto!

Read post #8 of this thread:

https://www.ford-trucks.com/forums/1...ml#post9800331

The PCV vacuum leak typically effects both banks. Your looking for a vacuum leak that ONLY has an effect on bank 2. (i.e, an exhaust leak upstream of the fuel control HO2S on bank 2, or a injector o-ring leak on bank 2, or an intake manifold runner gasket leak on bank 2, or . . . ..

 

His fault IS affecting both banks (see LTFTs for 1 & 2), it's just that the PCM only set the code for one bank. It happens.

 

Thanks guys. The only other data that I remember on The freeze frame was...

Fuel Loop Closed
load 64 or 68% or something close to that.

I will wait until it happens again and double check the data.

And yes, the PCV is on the passanger side. I pulled the hose off the drivers side and noticed it wasn't the valve. Checked the other side and still didn't see any cracks or seperation. Checked the PCV and it rattled freely. I dont think it has been changed for a very long time so should I replace it?