2005 Ford F150 4.2 V6 sets P0171 code only.. LTFT B1 reads 29.7 and never changes with rpm's LTFT B2 reads 3.5 + or - and fluctuates with rpm;s
FTST B1 READS 5.97
FTST B2 READS 8.22
O2S BANK 1 SENSOR 1 VOLTAGE READS .10
O2S BANK 2 SENSOR 1 VOLTAGE READS .07

Cleaned Maf sensor, checked for intake and exhaust leaks, changed pcv and checked fittings.
Truck has slight miss and hesitation but only sets P0171

 

No surprise LTFT1 doesn't change with RPM. It has 'biased' to the limit of what fuel trims can compensate for. The limit that triggers a lean code is +25% LTFT and + 10% STFT. So your are over that.

How did you check for vacuum leaks (THE MOST common cause of lean condition)? Since you have a scanner, monitor STFT while you 'blow' an _UNLIT_ propane torch all around, and UNDER the intake manifold, fuel injector base (o'rings), valve covers, even timing cover and oil pan, vacuum hoses etc - etc. If you hit any spot where there is a vacuum leak, short term fuel trim on bank 1 and/or 2 will go lower or negative VERY quickly.

Report back if you don't locate a massive vacuum leak. Subtle - random misfires could also cause it.

 

?????????????????? ^^^^^^^^^^^^^^ Ever find the cause of your 'P0171'?

 

Injector o'ring on #2 cylinder.. Replaced intake gaskets, injectors, and egr valve as well as water manifold in water pump and pcv hose fitting in rear of plenum. Truck has been put on back burner for now, should get back to it in a few days.. Hopefully before "Honey Do List" starts to grow again!!!