I've owned my 2008 F250 Larriat w/ V10 Triton now for 4 years and so far this truck has been awesome. Started towing a 7400lbs travel trailer with it not too long after buying the truck, so its towed most of its life during the spring, summer and fall months.

Up till now, towing has been beautiful. That I'm not really taxing the capacity at all, you can hardly tell the trailer is back there. And going up hills has never been an issue. If I want, although I usually don't, I can cruise up most grades at 65 to 70mph, the truck seems happy at 4200RPM. Though most of the time I keep it below 4000.

In any case, this past weekend this thing was ******* me while towing uphill. I lose power essentially above 3700RPM so taking the hill that I usually cruise up at 60, I limped up at 45...with my foot to the floor. At lower end and normal level driving, no issues at all. Acceleration from a stop, no issues. Aside from trying to climb above 4000RPM, I can't tell of any problem.

So I'm looking for some ideas here. I bought a fuel filter and will be putting that on tomorrow. I use a K&N air filter, although I just cleaned it before we towed a month ago and there were no issues getting up hills. The only other thing that comes to mind is the exhaust. The stock muffler on these things suck, I've already been through one Ford replaced on warranty due to resonator issues, now this one sounds like all the inners have fallen apart. So thats next to go as well.

Any thoughts from Ford owners out there? Could my problems be due to a blockage in my apparent failed muffler?? Could the fuel filter be bad enough that you only notice the problem at high speed/high RPM climbs??

 

Fuel filter, clogged cats, you might want to clean your MAF since you have an aftermarket filter. These are the first things that come to mind.

 

sensors are the first thing to come to mind, clean and or replace.

 

i wonder if you dusted the MAF sensor with oil from the K&N filter...

 

I was thinking the same thing! The MAF is so close to the filters and this would not be the first time I have heard of the oil from the filter screwing up the MAF.

 

Great feedback, thanks. Already changed out the fuel filter...was easy enough. Will look at cleaning the MAF and see if those two combined do anything. Will post results. Thanks.

 

I don't see where you mentioned how many miles you have on the truck. I recommend checking your fuel pressure at RPM.

You can dispel the urban myth about K&N air filters and MAF sensors here.

 

I run K&N in every vehicle I have, including the generator in my TH, I've NEVER had an MAF issue in 22 years.

 

Well the fuel filter didn't do anything. I checked the MAF sensor but it didn't appear to be mucked up at all. Tried towing the rig over the pass yesterday, same thing. I have a friend bringing his fuel pressure gauge in with him today, that will be another check to do. Looks like I might have to bite the bullet and take this thing in...was hoping to avoid the shops.

 

Have any CELs?
got a OBD2 scanner?

 

I don't have a scanner, so don't know yet. Need to get one though. Problem is I've been mislead by cheap scanners...any preferences for a good OBD2 scanner??

 

Check to see how much ethanol is in the fuel? I live in CA and fuel is 10 percent MIN by law. When I am out of state I get better performance and better MPG when I use fuel without it. I have seen 20 percent from some stations.


Just a guess.

 

I have pondered that as a possibility. Every place in town here in Idaho runs with up to 10%. Possible they are getting closer to the 10% maybe!! "Up to" is pretty vague really, could be .01% or 5%, who knows. Only problem is its been up to 10% the whole time I've owned this thing, so its hard to actually point to that since it wasn't a recent change.

 

Use the link below for REAL gas.


http://pure-gas.org/index.jsp?stateprov=ID

 

Fuel pressure is the big one to check. Sounds like it's starving for fuel.

As for K&N's, I was one of the lucky ones to get a K&N that started that whole "rumor" of K&N's ruining MAF sensors, in my '96 t-bird. Once I cleaned and reoiled it right, it never did it again. Turned out a bad run of filters were over oiled at the factory, and I happened to be one of the lucky ones

But yeah, CLEAN THE MAF