RPMs dropping uphill, Ford f-450

[Travel_1234]

We are experiencing odd vehicle problems and were wondering if anyone has any ideas. When going uphill (~5% grade @2500 ft above sea level), the rpms slowly decline, pedals wide open throttle. Dual cooling fans come on and there is an added noise and slight vibration.
The vehicle is a new to us ford f-450 pickup, 2013, 15k miles, all the tow packages and upgrades. We are towing a triple axle grand design momentum fifth wheel w/ dry weight of 14,500 and gross of 18,500. We have no toys and minimal stuff (first trip). The truck should be able to handle much heavier stuff..it’s about as big as we could go with a pick-up truck.

Thoughts?

[Grit_dog]

The actual problem is circled right on the grille and highlighted in blue!

(Ducking for cover now.....)

And yes I know what part of the female anatomy a Ram logo supposedly looks like, although I think that means other owners who point that out are pervs! lol

[time2roll]

Wait until you are in lowest gear, full throttle, and still losing speed.
That is when you start to worry.

[Grit_dog]

Sounds like Travel1234 was still trying to use gears 5&6 when they should have stopped upshifting at 4. Lol.

[rjstractor]

blt2ski wrote:
Assuming you are around 25,000 lbs total. 100+sq ft of frontal area. You need 150-175 hp to go 60 on a level ground. Another 50-55 hp per 1% grade. You are needing more HP than you have. Yes you should be slowing down some.
Also, I don't believe a 2013 has 400hp. But could be wrong.

Marty

Yep, like Marty says you're bumping up against the laws of physics. The 2013 is rated at 400 hp but it's not putting that much to the ground. People like to crow about how their rig can "pull 30K up a 6% grade at 80 mph" or some such nonsense, but typically they are fibbing about the weight, the grade, or the speed, or all three. To give a basis for comparison, a semi I sometimes drive weighs 30K empty and pushes a similar frontal area to your combo. Hammer down, it will pull a 6% at 60 with a good run at it, and it has 10 speeds, 515 chassis dyno certified horsepower and over 1500 ft.lbs of torque. Loaded to 72K it's more like 40, and that's not bad. So if you're getting pulled down to 50 or so on a 5% grade weighing 25000 lbs combined, it's not the truck, it's just math.

[cavie]

When towing always keep it in tow mode. Also drop it back one gear normal drive and leave it there.

[cavie]

When towing always keep it in tow mode. Also drop it back one gear normal drive and leave it there.

[Grit_dog]

Apparently OP isn’t interested in adding any more info.
Musta realized he had it locked in hi gear in manual mode or something.

[noteven]

A 9000 lbs truck plus 15000 lbs trailer will feel a 5% grade due to gravity.

The adaptive transmission takes a bit if time to relearn the truck is hauling something vs idling around in double overdrive in empty bob tail mode.

[ShinerBock]

If the OP's truck has a pickup bed on it from the factory, then it is not detuned. Chassis cab trucks have to go through a different emissions certification than complete trucks, and this difference in emissions certifications is the reason why they make less hp than complete trucks. Basically, chassis cab trucks have to control NOx at full load while complete trucks do not. This allows for the complete trucks to make more power since the EGR is not used under full load like it is on chassis cabs.

OP, even big mighty diesel trucks will slow down with enough weight, drag, and grade. As stated before, I would lock out 6th when towing that heavy up grades. Like mine, your truck has two overdrive gears, 5th and 6th, and in my opinion 6th is overdrive for unloaded or small loads while 5th is overdrive for medium to heavy loads.

Now if it generally doesn't slow down up these hills and it is just starting to then that is another issue and the first place I would look is your fuel filter. It may be clogged and you are not getting enough fuel to make the power needed. If you have a way to check actual and commanded fuel rail pressure then this will let you know you are either not getting enough fuel or the truck is defueling to keep temps in check. If it is commanding more that actual than you are not getting enough fuel and likley have a clogged filter. If it is commanding less than max(26-29k psi) and actual mirrors what is commanded then the engine is defueling itself to keep temps in check. Another issue may be turbo overseed which the turbo for those years was notorious for, but it would have thrown a check engine light for that.

[Mote]

That's a pretty camper even for an F450. You're bound to slow down on most grades.
Like others have stated I would start with making sure the air filter and both fuel filters have been changed recently. Dirty filters will restrict the engine ability of making it's full power.
The noise and vibration are probably the engine cooling fans kicking in high. They are pretty large and make a lot of noise if pulling really hard.

[azdryheat]

I recently got some bad diesel and couldn't climb grades. Once I got better fuel it was back to pulling great. Maybe it's your fuel.

[NRALIFR]

The 2013 F450 pickup isn’t a medium duty truck. The GVWR is 14K, so it’s still a class 3.

You’re not letting the cruise control drive it on steep grades are you? Unless there’s a check engine light, I’m going to say this is just a lack of familiarity with the truck. Make sure Tow/Haul mode is on, and perhaps be a bit more aggressive with anticipating the need for downshifting, and throttle. Use the +/- buttons on the shifter to force a down shift and lock it out of 6th, or even 5th if needed.

:):)

[RAS43]

Since the truck is new to you is all of the maintenance up to date, especially fuel filters? Could just be something simple.

[Grit_dog]

sch911 wrote:
A 5% grade and the altitude would cause additional load. If your maxed out in high gear you will slow down. Simple physics. Period.

There's almost zero altitude effect on a forced induction engine at that low altitude. Even a NA engine is only down about 7-8% from sea level (theoretically).

And @ksss, Ford didn't detune the F450 pickups, they were 400/800, but the C&C trucks took a serious hit, like only 300/660 or something like that. Super turds.
Still OP's truck may have just run outta steam.

However, until we hear what gear, rpms and speed, it's anyone's guess.