I have a 07 5.4 L with 101,000 on it, when I start it in the morning and it's cold the thing runs great, plenty of power and no hesitation, but after driving it for some time it losses almost all power, I can put my foot to the floor and I wouldn't be able to pass someone even if I wanted to, it will run fine for normal driving but accelerating is almost impossible, it just has no *****, it's also been getting terrible mpg. I've check the cats and they are fine, alot of guys with a similar situation said it was the maf sensor but I put in a new one today and there is absolutely no change, spark plugs are only a month old, I took it in to the shop because I can't figure it out and they have no idea as well, doesn't through a code or have any stored, has anyone had this problem and been able to fix it? Any help would be great

 

Change COPs, check FPDM above the spare tire.

 

Thanks I'll give it a try

 

Sounds more like a transmission issue, do the RPMs flutter a bit when WOT? If you can really floor it and it doesn't jerk back and pull, I wonder if a torque converter could be to blame. If not, perhaps you have an oil sludge packed engine. Do you have a programmer to monitor some DTCs? I would study the trans temp under regular driving conditions for a bit and see if it is getting much hotter than 160 degrees.

 

What about your fuel filter and injectors?

 

I had a similar problem with a car I had, and in my case it was a problem with an O2 sensor. The reason it runs fine when it's cold is that it is in what's called open loop before it warms up. In this mode the computer ignores the fuel system feedback sensors and goes to a set of predetermined values. Once warmed up the system goes to closed loop mode and uses the sensor feedback to the computer to control the fuel system operation. In my case a faulty sensor caused it to run like crap when it warmed up.

 

Thanks for all the suggestions guys, I haven't got a chance to look into her because I've been plowing snow like a mother *******er, the shop I took it too said they had no idea what's wrong with it and said they can't do anything for me

 

Time to find another shop.

 

Whats the FDRM?

 

It's FPDM ...

And it's this'un ting'um:

https://www.f150online.com/forums/ar...placement.html

 

Thanks for all your help guys, it wasn't the fdpm either so still have no idea what's wrong with her, not my problem anymore though, the dealer I got it from bought the truck back for the same price I paid so everything worked out in the end

 

That's amazing, how long did you have the truck?