Should overdrive be turned off when pulling travel trailer with 2008 F150

 

I had a 99 250 and when I was in town I turned off the OD but if I was on the interstate I'd turn it back on.

 

Very good question. The consensus seems to be that you leave OD engaged when NOT under load, and disengaged when you ARE under load. I'm mostly in line with Angus. Maybe disengage in town, engage on the highway, and maybe disengage on hills depending on performance needs. I actually leave it engaged in the city (flat) and disengage on freeway onramps. Hills and passing are definite disengage for me, but we're talking 70 MPH freeway hills in my area. Tough to maintain speed without lockup.

 

Mark Kovalsky, a retired Ford tranny engineer, says the computer program that controls the tranny is probably smarter than you are in most conditions. So put in drive and allow the computer to decide which gear you need to be in for the load and road conditions.

The one exception is in hills where you go up one hill and down the other, then do it again and again. The tranny will change gears often, and that's not good. Causes excess heat that the tranny cooler has to overcome. So in that condition, kill the overdrive until you get out of the ups and downs.

The tranny is programmed to not allow "hunting" between gears, but the ups and downs of hill country acts sorta like hunting, and that's no no.

Another condition I over-ride the computer program is when I see a steep grade coming that I know will cause a downshift. If dragging a heavy trailer using cruise control, the computer will downshift when needed, but it causes a harder jerk than I like. So I kill the cruise, and kill the OD while decelerating for a softer downshift, then reingage the cruise control at the lower speed for climbing the mountain.

For example, I usually cruise at 62 MPH, using cruise control with the tranny in "D". But I climb 6% grades at about 55 MPH using cruise control but with the tranny downshifted out of OD.

 

I am also along the lines of Smokeywren. I have found if I am pulling a decent load thru the hills on the highway at highway speeds I will leave it in OD as the torque convert engages very nicely and seems to pull much better at a lower RPM. I will shut of OD to stop the hunting that will take place when climbing hills on tight back roads. I do some times when I do not have a load on, as it maintains a lower gear and is ready to pull out of the corner. I also use it in decending, I have a hill that I come off on a 2 line county road that is 55mph. I will use O/D off to maintain speed control thru the engine, which by the way does a very nice job. I have the 5.4 in a 2005 SCrew.

 

Is this any different when your computer is flashed in tow mode? Thanks much

 

I'm not sure what you mean by "flashed".

Most late-model F-150s have a tow-haul mode that's included in the stock tune. You still drive in "D" and allow the computer to determine which gear to be in, but the computer changes the shift strategy when in tow-haul mode.

If you mean a hot-rod or towing tune that's flashed into the PCM (powertrain control module or "computer") to replace the stock tune, then it depends on the nitty gritty details of that tune (computer program).

I don't trust anyone yet to flash the PCM in my EcoBoost with a custom towing tune that adds about 50 or 60 horses and increases the torque for lugging a heavy trailer. No one has the experience yet to tune an Eco-Boost engine better than the factory tune. But with a 5.0L or 6.2L V8 engine, there are several tuners that have custom tunes that work good. The main advantage is those towing tunes will give you enough horses to climb normal grades such as a highway overpass while towing without downshifting the tranny.

On my '99.5 PowerStroke, the DP-Tuner 60-added-horses towing tune was a welcome addition to the truck. Without it, the tranny would downshift out of overdrive for every little bump in the road, but with the 60-tow tune it would stay in overdrive and go on down the highway.

As to whether to tow in overdrive or not, the towing tune didn't make any difference. It prevented the tranny from downshifting as often, but with or without the custom tune you still left the shifter in "D" with OD turned on, and let the computer figure out which gear you should be using for the current conditions.

 

Smokywren hit the nail directly on the head (as he usually does..). Unless you are hauling in mountainous conditions stick it in D and haul *****.. Simple, easy.

 

I hardly ever tow on highway. (Maybe three times a year from central Florida to Miami and back). I do tow my boat on a regular basis, all in town driving and it is just shy of 6,000lbs I am towing. I always turn O/D off while towing, especially in town.