Good evening,
I have been a faithful Ford man for as long as I have been able to drive. However I have always drove the older trucks, then last year I bought a 2004 F150 5.4 w/ 3.73 LS. When my wife and I moved down to South Carolina we towed a u-haul trailer and had the back of the truck loaded down with gear the total weight of both truck and trailer was somewhere around 11,500 lbs. The old truck had no problem even with all the mountains we went through in PA, and I kept the truck in OD with cruise set the whole time. About a month ago I traded that truck in for a 2006 5.4 w/ 3.55 LS. I towed with it for the first time today, me and a buddy had to go pick up our bikes. So I hooked up the EMPTY 8X12 flatbed utility trailer and we headed south, I got on 95 south bound and set the cruise at 70. The transmission kept having to downshift to keep it at speed and then we went up a very slight incline (where 95 crosses into Georgia in case anybody knows where that is) and the truck actually kicked off the cruise control. This can't be right, I am bringing it in to be looked at tomorrow at the dealership. The truck has the towing package, I can't believe it can't even tow an empty utility trailer without downshifting, plus I filled up the tank just before we left and the trip was 182 miles which sucked down 3/4 of a tank of gas. What could be causing this? This cannot be right. Any ideas?

 

from what i've heard the 3.73's are the ticket for towing...thanks for th reply in my thread

 

I don't really need the excessive towing of the 3.73's but I don't think the 3.55's should be that bad at towing, especially with that light of a trailer.

 

yeah, thats true....if the trailer is enpty i'd think it would tow it pretty easy

 

My truck needs to go to 2nd to pull any significant grade with a 1200 (empty) pound trailer. Even a slight grade doing 70 would make it kick out of o/d, tried it once with said trailer empty. Just lock the O/d out when you tow. I never use it, and the mileage isn't much worse. Ive gotten 14 with a 1000 pound popup camper, doing mixed city/highway, no O/D. My normal mix is around 11-13. It's a big, heavy truck, and will pull most anything you throw at it, but you trade off your mileage for that capability. Load it up real heavy and you'll probably be able to watch the gas needle drop. The 3.55's aren't helping any either, for any towing, the 3.73 would have been a wiser choice.

 

Reason being the 3:55 gears, yes the 3:73 will provide better towing! Nothing wrong with your setup you just need to disengage the OD.

 

get a stick shift, my truck has a 3.55 rear it never downshifts LOL. but seriously it's a v6 never had power issues hauling our boat(19' ski boat) and i always leave it in OD. even through WV mountains.

 

I agree the 3.73s are better for towing, but acorrding to Ford the 3.55 gears with a 5.4L V8 can tow max of 8,300 lbs. But disengaging the OD does help, it keeps the tranny from going in and out and searching for the right gear. But over all for light towing the 3.55 gears 8,300lbs is not bad.

2007 F150 XLT Supercab 4x4 5.4L V8

 

Stick shift! Good luck finding one, I asked multiple dealers and it just doesn't seem posssible to get a manual trans any more. I just got the truck back from the dealer they looked at it and said nothing is wrong, so I guess I will have to see how it does and maybe get 3.73's installed later on.

 

screw the 5 speed....you don't want one for towing....thats what i have now and it's a total pain in the **** shifting all the time.....stick with the auto....much easier....trust me i've been towing for 3 years now with my 5 speed and i totally hate it...and i love to drive stick it just is the worst thing ever towing with one....

 

I agree it's not as easy but saves a lot of gas vs automatic IMO. I've been towing the boat for 7 years with this truck, wouldn't trade it for anything.

 

well, i have a 4.6 L and it's a 5 speed....i don't drive fast at all and i'm very good to the truck...my friends call me grand-pa because of the way i drive....i just like to take good care of it and i get 18 mpg....when i tow my quads on the trailer up north i get like 11 and their is no way on this earth i'm keeping it in 5th gear going up the hills...never happen and i seriously doubt anyone else is either....my uncle has a 4.2 with the 5 speed and we towed my quads on the trailer with that one time and it was a total dog going up the hills....

so, if i'm going to get 11 mpg towing the quads up north i'd rather get 11 mpg with a 5.4 and a auto and just sit there and not shift all the time...

 

i pulled 14-15 MPGs when i pulled my boat down to smith mountain lake in VA from here near Mansfield Oh. Almost the entire trip is through the appalachains. Truck weighs 4500 with me and full tank and trailer w/ full tank fuel is 3500 Plus 4 wheeler and camping gear in bed. I could all but call my 4.2L a dog, but yep i shifted down on about every up grade. No they're no powerhouse but they are also a six cylinder- and in her prime she got over 18 mpgs with my foot in it(always was so couldn't tell ya when i was takin it easy). 145,000 HARD, HIGH REVVING miles and still going strong, and still getting over 17 mpgs. Shes getting tired though.

 

something sounds wrong. I've traveled that stretch of 95 with a 3000lb trailor and have no problems keeping it in OD. I have the same set up as you except mines an 04. mileage stays around 13 on that stretch of hwy. I know the hill your speaking of, its not very steep.

sorry, mine is 373. can't tell you if that's typical or not.

 

The 3.55 will cause everything you mentioned. 3.55 is a running gear, and even though they are rated to pull, you will work everything in the truck harder pulling with 3.55's. It will take more to pull off from stops, working hills, etc. The mileage difference between a 3.55 and a 3.73 will only be noticed if you do a lot of highway miles and are not towing anything. If it were me, I would spend the money and have it regeared to a 3.73LS.