Oh4fx4

Hey guys i just bought an 04 fx4 5.4 i been getting a code p0174 running lean bank 2 and it shakes at 1100rpm in park neutral and overdrive at same rpm. I been trying to fix for few months now. I did spark plugs, fuel filter, tried other cops, cleaned maf, smoke tested for vacuum leaks, changed 02 sensor, no exhaust leaks. I tried unplugging the vct solenoid and the shake stops when reving at 1100rpm. What does this mean?

BadFish523

That's a tough one. Any codes?

redfishtd

Just guessing maybe maf damaged . No other codes? You didn't find any vacuum leaks on smoke test, My explorer had a vacuum leak on the fuel vapor purge solenoid, alcohol fuel ate plastic . . My friends leak was on fuel pump gasket on top of tank, folded over on installation . . Took a long time to find these with a smoke machine several times . Gas cap is another source of leaks .
Just giving you an idea of smokeleaks outside of engine compartment .

Oh4fx4

EBC-150

It can if it's stuck and is throwing the valve timing off. On an '04, it's 'easier' to remove and inspect. You'll need to remove the power steering reservoir, pop the seal and get at the mounting screw. I've seen a broken screen get lodged into the plunger, binding up the solenoid.

Oh4fx4

Ok i will try removing and inspecting.

F150Torqued

I respectfully agree and throw my full support behind removal and inspecting. (AND Soak the spool valve part below the Coil in some STRONG cleaner - "B-12 Chemtool" - then OIL and actuate it several times throuth a resistor (50 ohm or so) on 12 volts.)


BUT NOTE: @Oh4fx4 mentions the rough running shake clears up with Bank2 VCT unplugged. RESULTS of UNPLUGGING = (1 The PCM shuts down VCTENA (conditions correct for variable valve timing) when it detects an open circuit condition in a VCT solenoid circuit - and sets a DTC. (It knows it can't retard only one bank). (2 When VCTENA is shut down - there is NO duty signal applied to EITHER VCT SOLENOID. (3 With no duty signal applied to either Solenoid - Bothe cams are at base, default, NO RETARD position. There is effectively NO variable valve timing exactly like LOCKOUTs are installed. (4 under THOSE conditions, there is no expiation for the OP's symptoms.

The OP might benefit from some live data. https://www.f150forum.com/f4/final-r...4/#post5133357
The OBDII signals CAMERRR and VCT2ERR show the error (in camshaft degrees) between retard requested by the PCM (RCAM) and the actual camshaft positioning (as read from the CPS) on both Bank1 (CAMERRR) and Bank 2 (VCT2ERR). According to the Motorcraft Theory of Operation, if the camshaft error exceeds 5 camshaft degrees - for more than five seconds, that = over retard or over advanced as appropriate.


All this makes me wonder if Bank2 solenoid is not closing off completely (electrically somehow). Idle oil pressure (& perhaps very small oil flow through VCT) is insufficient to retard Bank2, but with some acceleration toward 1100 RPM increases oil pressure enough to move the Phaser toward retard on bank 2. (( This is all just conjecture)). The gauges would show it for sure.