Hey folks, just an observation followed by a question.
Truck = 2010 f150, 5.4, 3.55's, 2 wheel drv., tow pack, weight dist. hitch.
Trailer = Jayco 23', tandem axle, dry at ~ 4685 lbs.
We travel as light as possible, no kids so no kid stuff. Safe to say besides the trailer we may carry 400 lbs of stuff., no water.

Dead flat highway, around 65 mph, (tow/haul on) spinning around 2300 rpm in 5th. If I lift the accelerator it will grab 6th and I can ease back on the throttle. Shortly after it will drop into 5th again. Constantly hunting between 4 & 5 it seems. At these times the lie-ometer reads about 26 l/100 km (9-10 mpg).
I tried to push the speed to get over the 5-6 hump, not very successful, doesn't want to keep 6th. At that speed lie-ometer says about 30l/100 km ( 7-8 mpg).

Does this seem normal ? Perhaps this newb is expecting too much.
Not bagging on the truck at all, love the truck.
The fuel is understood, the hunting around for gears is my only real concern.

Any feedback would be appreciated, thanks.

 

Leave it at 65 and in tow/haul, and let it run in 5th.

 

Your gears are killing it. I tow quite a bit with a 6000+ pound travel trailer. Mines a 2010 5.4L Max Tow with 3.73's. I run in tow/haul always, and to get into 6th, I have to break 60mph on the flats. The slightest incline downshifts easily. Fourth only rears it's head on heavy hills.

 

Thanks for the input guys.

 

Sounds pretty normal to me as well. If you were running 3.73 gears it might hold 6th a little more, but remember that 5th is an overdrive gear on the 6 speed tranny as well as 6th. Just drive like you have been doing. Don't tow with the speed control on, it will make it hunt for gears a lot more. Anticipate inclines by buliding momentum before you get to it.

 

I agree with GLC. 5th gear, 2300rpm, 65mph. If it can hold that and get 9-10mpg, keep it there. That's a god as any gas engine gets towing a full walled travel trailer of any weight. I run at 2700-2900rpm all day long because I cannot hold my next gear, which would be around 1800-1900rpm. Fuel economy stinks in my old 2V 5.4L comparably, best is 8.2mpg when I brought it home empty with a tailwind. 2500 towing miles this summer, about 7.3mpg average.

Ford added selectshift for the 6-spd trans in the 2011 F-150 which can limit the top gear in tow/haul mode, which is great for RV towing to limit to 5th gear, avoid hunting.

 

Good'nuff for me, thanks again guys.

 

Same issue with mine. It seems to hunt around 65mph constantly, 2WD and 3.55LS like you. Im towing more trailer though (26ft enclosed, 6000lb when loaded for a race weekend).

I discovered coming back from CMS that 72-74mph seems to be the magic point at which it holds 6th for the most part. Only downshifts to 5th on the bigger hills.

The problem with people saying "let it run in 5th" is that it doesnt do that. As soon as the load decreases, the transmission dives to 6th. The constant shifting between 5th and 6th heats the transmission up pretty significantly.

Ill be going to a 3.73 gear as soon as I can find a used one.

 

And that's why Ford added Selectshift for 2011 to have tow haul and limit the top gear too.

 

Thats peachy. Nice to know 09-10 owners can consider themselves beta testers.

 

I tow a 4 ton TT with my 09. I just set it to tow/haul mode and don't worry about it. My gears are 3.55 - it shifts more than when I don't tow, but I figure that it is behaving exactly how the engineers at Ford want it to.

 

If you watched your transmission temperatures, I guarantee you would worry about it a little more. It gets hot in a hurry.

 

I'm not sure I understand how constant shifting causes big temperature increases. Don't the shifts only take less than a second. If the trans shifts 2 times a minute then thats 2 seconds the clutches slip and add heat. I can see where an unlocked torque converter adds heat to the trans fluid because rotational energy is converted to heat when the torque converter "slips" and heat is added constantly as long as it is unlocked. That being said, I would not like the trans to constantly hunt for the right gear either.

 

I have a CTS controller, so I can and do watch my transmission temperatures. (The Ford gauge stays in the middle from around 150 degrees to at least 210 (highest that I have seen) - I'm told that it shoots to the right around 265). My transmission gets hottest pulling up a big hill, it doesn't get hot running on the flats, even if it hunts a liittle.