I am at ~72K miles and my mileage has dropped off considerably. I recently did the timing chain fix and an induction service to remove carbon on the valves. This improved my mileage by about 1 MPG, nothing to write home about. I do run a larger AT tire, but even since they've been on, I have seen the mileage getting worse. I am at about 10 MPG in town. I have to fix an exhaust leak on my driver's side, which I know can contribute to the low MPG I am seeing. While I am in there, I plan on removing the downpipe and looking at the cats closely. There is a fair amount of sooting at the tail pipe, you'd expect the soot to block the substrate in the cat and eventually throw a code sooner than later. I guess that stuff "Burns off" once the cat gets to a higher temperature?

On the ecos, once the turbos are taken out of the power equation, the motors are completely inadequate for a truck and MPG plummets. The truck becomes a complete turd. So I suspect for the high mileage ecos there are probably some turbo performance issues which are causing folks to push harder on the pedal to achieve the same power as before. Certainly tuning is a big part of this.

 

You should look into this.

https://www.f150forum.com/f38/2011-5...-fixes-128636/

 

Thanks for the link. I had that procedure done by a local shop when I finished the timing job. Also the truck runs great. No hesitation or misfires, idles great too. There are no obvious signs of something wrong. I know the exhaust manifold is leaking on the driver's side, so I will probably address that and reassess. I'm just throwing my observations out there so the OP doesn't feel like he's crazy. There are a fair amount of perfectly running trucks out there that just get ****-poor mileage.

 

I am the OP lol.
Like I said earlier 5.0L and 3.5L are not apples to apples.

Also, no one ever answered my questions.
1. Is there a serviceable PCV valve on the 5.0?
2. Is there an external fuel filter?

 

1. Yes
2. No

 

Hey Skipy,
Do you have a link to a write up on location and replacement? Been having trouble finding one.

 

NVM finally found it.

 

Never done either. But the PCV is right on the passenger side near the front of the engine. Looks like a 2 minute job. Bugger is $25 or more. I think PCV cost me $4 for my kid's car.

 

I should pop my hood more lol.
found it on amazon for $14.

 

I saw Scotty Kilmer (youtube master mechanic) clean a cat with lacquer thinner in the gas (around 10:1). Not sure I'd try it but he's a pretty smart guy. If they are too clogged up, he removes them and soaks them in detergent.

Youtube