I'm getting lean codes on my 2005 5.4l F150. The codes are p0171, p0174, P2195, p2197. My fuel trims are also way off with my LTFT @ +30% both banks and my STFT @ +25% both banks. I haven't visually found a vacuum leak but I will do a spray test tomorrow. However, the baro reading is showing 13psi with the engine off, but I'm right at sea level, shouldn't it be 14.7? Is there a baro sensor that is broken or can this be reset? Also, I noticed that my B2(drivers side?) O2 sensor (s1 and s2) are both stuck and not oscillating, could this be part of the problem (even though it's showing lean on both banks?)
thanks!

 

Has anything been done to the exhaust system? All stock? When were the O2 sensors last changed, if they were, are they Motorcraft?

Has anything been done to the intake? All stock? Have you checked and cleaned the MAF sensor?

How many miles on this truck?

 

It's a new to me truck so I'm not sure about the history. The exhaust looks to be stock and the O2 sensors look a bit older with some surface rust, I'm not sure of the brand. Is there a test I can do with a multimeter to check if the O2s are good and also the harness? The harness to the sensor has a few areas of burned looking wires? Or is it worth just replacing both upstream ones and repairing the hardness?

The intake is all stock except all the vacuum lines look like they were replaced at one point (with non-stock tubing). I cleaned the MAF with MAF cleaner last night and didn't seem to improve. Is there also a multimeter test I can do with the MAF?

The truck drives decent, just has a bit of a low jumpy idle, but the fuel trims seem super far off I dont want to cause any big problems by not correcting it.

 

Leave the sensors and harnesses alone unless you can actually see a definite fault. Your O2 sensors appear "stuck" since the the engine is running max enrichment.

That only works if you're monitoring either the STFTs or the upstream O2 sensor voltages. You'll have to reset KAM and hope the PCm can enter closed loop operation to do this. Spraying and listening rarely works (computer is too fast to compensate) and then usually only if you have a severe leak that you can hear anyway.

Did you check the PCV hose and fittings from end to end?

 

I'll unplug the battery overnight to reset the KAM and I have a scanner so I'll look at the STFT while I do a leak test tomorrow.
I looked at the PCV line (the insulated one on top of the driver's side valve cover) and it looks to be ok but I'll leak test it.

The truck also smells very strongly of fuel after running it, which I think is odd if it's actually running lean?

 

It is NOT running "lean", it is running pig rich. That's why you smell fuel.

"Lean" codes do NOT mean the fuel system is actually running a lean condition, it actually means the opposite. The proper definition of the "lean" codes is that the PCM has reached it's limit of enrichment but the O2 sensors are still reporting a lean exhaust mixture. This condition is usually simplified as 'over-aired' (compared to what the PCM is detecting) or 'under-fueled'.

If the codes are set at idle, it's usually an unmetered vacuum leak or a MAF misreporting air mass. If it's set under heavy load, it's often a fuel pump that's not capable of supplying enough fuel under high demand. You'd need to look at the freeze frame data after the DTCs are set if the occurrence is not obvious.

Make sure you check the full length of that PCV hose.

 

Thanks! That makes a lot more sense than it after running lean. It smells like gas and it says I'm getting 10mpg so it makes sense that it's actually running rich. It's trying to give +50% extra fuel but I guess if there is a bad vac leak the O2 will still read lean? Or possible exhaust leak before the O2?
I'll check the pcv tube tonight, do I have to cut the foam off to check it all out I'm assuming?

Here is a freeze frame after a KAM reset. LTFTs started at 0% and quickly maxed out at ~30%.


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Apparently someone did a very poor job of replacing the exhaust at some point and the exhaust pipe was coming in contact with the evap canister and put a large hole in it. Could this be part of the problem? Is there a way I could plug off the vacuum line going back to it from the engine until I can get the exhaust repaired and new evap canister ordered?

 

I replaced the pcv tube with a new one, no change unfortunately. So I have +%50 STFT after kam reset in both banks, but if I unplug the MAF it goes down to +15/+25 in banks 1 and 2, which is way better (probably still have a vacuum leak). The truck stalls if I plug the MAF back in while it's running. Does this indicate a bad MAF?

 

I have a 05 F150 5.4 3v and I'm unsuccessfully trying to find out why I have maxed out fuel trims. I have +53% STFT on both banks (after kam reset, 0% LTFTs) at idle. I replaced a bunch of vacuum hoses and no other signs of vacuum leaks. However, the "baro" reading is 80kpa but it should be 101kpa (I'm at sea level). How is the "baro" on these vehicles calculated? There is no baro sensor right? And how do I reset it? (Previous owner replaced the MAF with a generic brand one, but I cleaned it with no change)

 

Any actual fault codes or operation/drivability issues?

No BARO sensor or any other sensor that can measure barometric pressure on your truck. A BARO "reading" may not be applicable to your system.

 

Threads merged, sorry about that! The codes are p0171, p0174 and P2195, p2197 after the LTFTs get updated. I know there is no baro sensor but there is a PID for it and it shows 14.67psi in the manual for the reference value in all conditions. Mine is 11.6psi. also, here is what they fuel trims look like when I start it up, they march straight up to max

 

Until the system enters closed loop operation, the trims are per-defined by the PCM's calibration. Make sure you're not going down a rabbit trail...

 

The screenshot is after it enters closed loop. Open loop it just says 0% STFT/LTFT. As soon as it enters closed loop (after a minute or so) trims immediately rise. It smells strongly of gas and is getting 9mpg or so it seems like there is a miscalculation somewhere and wants to dump all the fuel it can in to get to the correct af ratio, but can't get there.

 

I'd be suspicious of that aftermarket MAF. Have you checked its readings for rationality?