I have a 98 F250 with 5.4L... I am only getting the one code of P0174. No others at all. Is this directing to somewhere special. Most of the issues I find report two codes usually together but I only get one.

 

When two codes pop it is usually something that affects both banks, like low fuel pump pressure, dirty MAF, vacuum leak between the MAF and the throttle body, etc.
Single code is usually something that is unique to one bank - intake runner vacuum leak, a dirty injector, etc.

You might want to check the LTFT of each bank. Although the P0174 set, the fuel trims of bank 1 may be a few percentage points away from tripping the P0171.

 

Sounds like a good start but what is the LTFT?

 

L-ong T-erm F-uel T-rim.

It is the percentage of fuel the PCM is adding (if trim is positive) or subtracting (if the trim is negative) from the factory supplied base
base setting.

When the sum of the LTFT plus the STFT (Short Term Fuel Trim) exceeds about +30% it will set the lean code.

 

Ok I’m getting this thread going again my 03 5.4l is running the same codes and I was checking out the vacuum line and me having a K&N intake the vacuum lines going into the intake tube have fuel line adapters for them. I knocked one and it fell off the intake tube. Advice to anyone still having this issue check you hose claps if you have an aftermarket intake. I’ll update if mtf light comes back on but my tuner shows normal fuel trim now