Hello all,

I'm new here and starting have a lot of issues with my truck. Thought I'd reach out to those with experience and knowledge greater than I and ask for some insight as to what may be happening with my truck.

I bought my truck used about 3-years ago with 90K miles (2009 Ford F-150 XLT 4wd with the 5.4L/3-Valve), with no mods to the truck it’s all stock items. Presently it has 127K miles on it. After I bought the truck, I changed all the fluids (front/rear differentials, trans axle, transmission fluid & filter). I’ve always maintained regular engine oil/filer changes. At the time I was OK with the mileage (12 city/16 HWY). It’s what you'd expect from a big truck with a V-8 engine.

However, the mileage started slipping. Now lately it started misfiring really bad. Then about a block from my home I got the dreaded blinking check engine light. After I was home and in park, I turned it off and checked the DTC and of which I found no defects. So, I replaced the spark plugs, coil packs...all with the newest updated version from Ford Motorcraft. Additionally, I replaced the air filter (standard filter), and cleaned the MAF sensor. With all that done it does run better without the misfire. However, according to the mileage counter and the numerous fill up’s…I’m now getting 8.7 MPG no matter what. So, I added a few bottles of Chevron with techron fuel injector cleaner to the fuel system and slowly it’s came up to 10.5 MPG. Still not what it was getting originally.

I know these trucks had issues with the timing system (timing chains & Phasers) would that contribute to bad mileage? Since I was driving it slowly for a short duration when the blinking check engine light came on...could that have burned out the catalytic converters…that quickly?

I have checked the DTC again there were no codes for the catalytic system in general. I'm not hearing any noticeable vacuum leaks. I asked about the fuel filter and according to Ford it’s in the tank incorporated with the fuel pump...they call it a lifetime filter and say it shouldn’t need changing. I checked the price (very expensive) on a new one and apparently it comes as a unit both the pump/filter as one. Should I chance it and replace it?

I'm scratching my head as to what to do or check next?

Any help would sure be appreciated!

 

On the engine there is a fuel rail , all the injectors are fed from it, there should be a fuel pressure regulator with a vacuum line attached to it. remove the vacuum line and see if any gasoline comes out of it. If so the diaphram in the regulator is ruptured and the regulator needs to be replaced.
Excess fuel can get into the intake manifold that way and provide an extra non controllable fuel mixture resulting in a super rich condition which would cause the check engine lite to come on and be blinking. If the engine was driven long enough with that problem it could destroy the converter. If it was one injector the PCM would disable that injector and prevent destroying the converter , but cause a misfire due to no fuel into that cyl.
Does your tool provide fuel trim data ?

 

Thanks for the information. I'll check that tomorrow afternoon!
As far as checking the fuel trim status...I just downloaded software called Forscan.
I haven't really had a chance yet to poke around with the various functions it provides but I'll check for it.