Sorry, I kind of thought you weren't getting enough power. That's what I get when I should have been asleep instead of replying to forums.

Has the tranny fluid ever been changed? How about the torque converter? Is it on the way out? I don't always trust what the dealership tells me... as I am sure you and a lot of others would probably agree.

 

If a transmission is downshifting or unlocking the torque convertor, it it has everything to with the engine's power, not the transmission itself.

FYI: 265/70R16 is an inch smaller in diameter than 265/70R17.

 

I just returned from a 1200 mile trip to Sebring Florida in my 04 Scab 5.4 w/ 3.73LS and towing pkg. I was towing a 3200lb Mustang on an 1800lb trailer and it towed like a dream. I averaged 12.5 mpg at 70mph and I even had the cruise on for awhile. I couldn’t be happier with the performance of my truck.

 

SOMETHING is wrong with a 5.4 that can't tow 3,500 pounds easily.

I recently towed a 3,000+- lb. '67 Mustang on a 600+- lb. tow dolley about 250 miles. It would hold OD in cruise control at 70-72 mph, though I would turn OD off for passing or anytime I was around other vehicles. Once or twice took it up to 80 mph so I could pass quickly and get out of the way of faster vehicles (Interstate 5). Pulled the Altamont Pass grade at 65+mph with OD off.

I have a 4.2 V6 running on lousy CA fuel. Averaged 14.2 mpg towing the load. Overall, it towed much better than I expected.

 

APT, there isn't a 1 inch differnece in the 265/70 16 and 265/70 17, they are almost the same size. different amounts of rubber on the sidewall is it, meaning rim to tread.

Secondly, because it can't hold the trans locked. You can feel it almost slip trying to stay locked. If it downshifts it still has to work hard as heck to stay at speed or gain speed. Fuel filter was done less then 10K, trans at the same time(twice for good measure) and air maybe 3K ago.

 

I don't think so.

Example: Michelin LTX M/S

P265/70R16 = 30.7
P265/70R17 = 31.8

I would say that there is quite a size difference - more than an inch!

 

Interesting my tires according to tire rack are 31.2 and are over half worn, neither her or there, thats 1/2 an inch, come on ford is dreaming .5" gain in tire size (ground to axle) cuts off 500 lbs of towing. CHEAP **** is what I believe this truck, I'll definatly be going back to GM on this one. I need something with some *****. Think about this, ford can barely get 30K out of a tranny in a crown vic p51 and they are gonna use it in a truck with a GCWR of 12500 lbs????? I know this has to be a tranny issue of trying to get power to the ground. I just can't see how they rate these trucks do you think they just pull numbers out of a hat?

Edit: I'm just voicing my disappointment in this product, had I paid for this vehicle new (35K sticker) i'd be fairly pissed. paying 17K for it makes me upset but you live and learn. Some people on this site will deny that this could be true, that I don't know what I'm talking about or there is something wrong with this truck.

 

Out of the 70,000 some thousand members to this website you are the first guy i have ever heard complain about the performance of the 5.4 for pulling such little wieght ever. But its whatever you want to think.

 

The amount of rubber is similar, but the rim is an inch larger in diameter, which equates to about 3.3% larger diameter. Another 5% between 3.73 and 3.55 gears on GM & Ford.

Believe it or not, the engine tells the transmission when to shift and when to lock up the torque converter. The transmission does not know when a driver goes to wide open throttle for example and wants to downshift. The engine controlelr gets the information, determines basd on calibration that the driver watns more power than is availible and requestes the tranny to downshift.

I understand your displeasure from your towing experience, but it is clear to me you do not have a great understanding of powertrian systems.

 

APT, I have a great powertrian control background just not with this ford junk, all GM, which, uses quite a user friendly setup. I also wonder what ford was thinking using one ECM as far as I know, to control the engine and trans, they should take a cue from dodge and GM and go with a ECM and TCM. I also know that there are preset programs for this but, when the trans cannot HOLD (READ HOLD) the power the engine is making, then yes, there are problems, it's called weak clutches. It has nothing to do with a computer, it has to do with line pressure which holds the clutches in gear. It could be the solenoid (one of the two that the trans uses for forward movement) or the clutches or the pump seals, or the valve body, who knows, but the problem has to be trans related.

 

Cliles55,
Can't tow with the Superchip in performance mode and the tow mode made no difference in actual up-the-mountain towing power so I took it back within 30 days and they refunded my money.

 

ferroequine -
The dia. of a 265/70 /17 is 31.8"
The dia. of a 265/75 /16 is 31.6".
You had typed in 265/70/16.
There are almost identicle in dia. size. the 17" rim has a 70% sidewall to tread ratio and the 16" rim has a 75% sidewall to tread ratio. smaller rim but more sidewall.

I reread his post, is he running 33" tires on the Jeep or the F150. If the F150, then his problem is the 3.55 gears with the 33" tires. Also, 3.55 gears arent even good enough for towing heavy loads with stock tires, let alone if he does have 33" on the truck.

I am running 305/70/16 Xterrains and had the 3.55 gears. My tranny would be constantly downshifting on the highway with the slightess grade or headwind. I had 4.10 gears installed and it is a world of difference. before I would have to have the pedal to the carpet to maintain 65 up hill and it would be always downshifting because in OD the RPMS are too low to maintain the speed.
Now I can pull the same hills doing almost 80 and in OD. And at 70 mph I am at about 2100 rpms.
I would say swap the gears to 4.10's.

oh yeah, my mpg actually went UP with 4.10 versus 3.55. With 3.55 I had to use more throttle to maintain highway speed because RPM's were so low and I was always driving around in 3rd because it would downshift all the time, and my mpg were about 12.
with 4.10 I am using much less throttle to maintain highway speeds, stay in OD more and so far my mpg are at least 15.

 

I'm running the stock 265s on my 150, 33s on the jeep. Eitherway it is rated to what 8000 lbs from the factory? Just my .02 cents.

 

I beg to differ here. I have a 2003 4.6L 3.55 LS 150. towing up grapevine with full tank of gas plus me and my Girl and dog including my ATC toy in the bed...not to mention the 23 foot TT trailer i tow with a min of 20 gallons of water, Lp, food, gear, etc which bring my total weight of my trailer to 5900 or so..give or take. No problem going up the grapevine, or back down both ways. i have gone up at 50-55 and down and never needed the SLOW OVER WEIGHTED TRUCK LANE!

Grated im not in race anway where as well.

Not sure if your TALKING just bout the 3.55 or the 3.55Ls, but i think you need to tow my truck and trailer up and down the hill and you will change your mind.


P.S when ARENT you in a head wind up grapevine???

 

Tommy that is the most random statment ever made. 3.55 LS or 3.55 open is the same driving down the highway. The gears don't just change rations because of a limited slip option, a LS makes no difference in towing on firm surfaces. Secondly, what is the RPM your running at towing your load, 4000 RPM ? I'm talking about 1900 to 2000 RPM lack of power or torque. If I was willing to stand on the go pedal, tear the **** out of my trans and engine then yeah it would go 80 or 90 no problem.