Down the highway at 70 mph was good (16.6 mpg)...pulling around the ramp was good...Going 50/55 mph on a road with very small hills with the cruise on was a @#%! nightmare.

Going down the hill the rpms would start coming down (way down). At the bottom of the hill (very small hill, more like a dip in the road) the speed would start to drop and after it had dropped down to about 5 under the set speed all hell would break loose.

The transmission would shift down a gear (seemed like two maybe), the truck would buck violently and the RPM's would go higher than I would ever put them on my own. Then it acted like it figured out it made a mistake and would quickly shift into a higher gear. By this time the speed was up to 5 mph over the set speed, it would let off the gas..everything would calm down...and then it all started over again at the next hill.

Overall it was a very disappointing experience.

PS - Tow haul works great if you don't mind revving the shat out of the motor and being thrown through the windshield when it shifts from 2 to 1.

 

Rick

You neglected to mention the truck you have...????

 

Sorry....2004 with Oct 2003 motor, F-250, KR, 6.0, 3,000 miles, not oct or dec flashed - PI still works, 3:73 rear end, auto transmission, 265 tires (60 psi front-70 psi rear), 15 mpg city - 18 mpg hwy computer is 1 mpg optimistic, delvac 1 motor oil, egr disconnected (can't tell any difference though), diesel additive evey other tank (can't tell any difference though)

 

My 04 F250 with 373 gears pulled my camper that weighs about 7500 pounds to Fla at 70 -75mph like it was nothing. I think it would have towed it at 80 or 90 if I was crazy enough to try it. I did pass a truck once and when I looked down at speedo it was at 80 I backed off. You must have something not programmed right.

 

try Going 50/55 mph on a road with rolling hills with the cruise on...then lets talk.

 

Been there done that . . .

I have an '03 F-250 built in Feb 03. It has the Dec flash, but I've towed my trailer on several different flash versions and still had good results.

I'm towing a 30' Weekend Warrior trailer that is usually loaded such that the total combined weight of the truck and trailer is around 18,000 lbs.

I have the 5 speed auto and use the tow/haul mode most of the time.

I've towed it on the flat, up/down 6 to 8% grades and on rolling hills, all with good results.

The Dec. version of the flash changed the transmission operation a bit to where in high gear the torque converter unlocks when you let off the throttle if you are above a certain speed. I think that in general this will improve fuel mileage but can be a bit annoying if you are winding down a curvy road. A tap of the brakes will relock the torque converter, but if you are goind up/down and around a curvy road then you are constantly having to tap the brake pedel to get the transmission to stay locked.

Most of the time though it is nice to be able to coast down a hill and maintain speed.

If I'm on a road where there is too much up / down grade, I don't use the cruise control anyway because I try to get a bit of a run going back up the next hill.

I average about 9 or 9.5 mpg pulling this load - depends upon my tow speed. The worst mileage I've ever had was on a flat section towing into a headwind.

Daryl

 

Rick,

How long have you been towing? One of the first things I was taught (learned) is not to use cruise on those short hills where the transmission is constantly shifting back and forth. The way cruise works it will give just enough fuel to maintain speed going down hill, and then will give lots of fuel to maintain speed up the hill. If the transmission requires shifting, this will occur also. Heck, my pickup truck with no load will do the same thing you just stated, driving in the HOV lane on my way home from work. There is a series of small rolling hills, and first I will be coasting down, then at the bottom, cruise control will start to add gas (my pickup is a gasser, my new X is a diesel ) sometimes a downshift of the transmission will occur and when that happens, hold on because it is like it hit passing gear, really starts to fly and at the top of the hill, oops, no gas, going over the set speed, and slows down. So, from what I have read, your experience is normal at least as far as I am concerned. I tow a 28 foot travel trailer weighing 7000# with my new X. Really love the power and the transmission.

 

I would not use cruise control on rolling hills, lots of turns, up mountains or country roads. I would only use it while on long sections of interstate going over 60 mph. I think that is what it is made for. Even on interstates where there is a lot of traffic I turn off my cruise control.

Try those same roads without the cruise and then come back and tell us what it is like

 

I've towed a bass boat off and on for 26 years, the last 15 with a manual transmission (no jumping back and forth with that baby).

Yes, working without the cruise provides for a smoother and less stressful tow on the hilly road I mentioned.

I guess I'm just disappointed in that I thought with 500 lbs. of torque; I would be able to set the cruise on any speed and just have it chug along.

For comparison, my friend has a 1997 Dodge (Cummings), auto, 3.73 (basically the same truck as mine) and it functions much better given the same conditions. He can set the cruise on 50 (same road) and it never shifts and the motor hardly ever changes RPMs.

Heck, the wife’s Tahoe doesn’t shift back and forth and rev up and down like my 6.0 does under these conditions.

I agree if you get the Ford train moving about 80 and it will go up and down hills with little effort (and get 16 mph doing it).

 

I think it all comes down to the computer and the vehicle. I have owned some cars/trucks/mini-vans and none really worked the same. A Toyota Camry I once owned would stay rock steady on the speed set under most driving (mountains excluded), and the Town & Country mini-van would vary as much as 5 MPH up and down hills. My last Ford P/U would stay put also, but my Dodge P/U behaves like your comments said. My 04 Excursion varies about 2-3 MPH on hills when not towing anything, really never looked while towing due to not facing any hills with it (just some rolling small ones, hardly noticed). Come spring break, going to tow approx 2000 miles. Will report back (if I remember and get time) on how trip went with fuel milage etc. I did this type of report about 2 years ago with my 02 Excursion, was long but very detailed.