[Jackpine]

If you have the tow package, I think you have 3.73 gears, like me. Are the tires stock, or have you mounted bigger ones? That would hurt your towing performance.

Aside from that, you have a heavy truck, like me, and I suspect your trailer is a bit on the heavy side too, with tandem axles. I really think, however, the problem is caused by the trailer's frontal area. If you look in your owner's manual for the truck, you'll see that Ford has a limit on that. You're probably pretty close to the limit.

Ford also recommends that you lock out the overdrive when towing (or at least suggests that you do). In your case, with the transmission constantly downshifting out of 4th, that seems like what you need to do. It's a result of the high drag induced by the large frontal area of the trailer. Drag increases as a square of the speed, so for every doubling of speed, drag goes up by a factor of four.

If you check my albums, you'll see what kind of trailer I pull. It's about 3600#, but has a low frontal area in the "tow" configuration. I can normally pull it in 4th gear, but if I'm on an incline, for any length of time, I drop the truck into 3rd. I try to cruise at 65 mph, and am careful not to exceed that because of the speed rating of the tires.

I suspect your truck/trailer combination is simply going to be happier at a lower speed. But, when you ask for a tow tune, make sure Bill knows all about your experiences here. DO tell him the weight of the trailer and tell him about the frontal area too. The more information you give him, the better he can optimize the tune you need.

The "drone" you heard is probably "lugging" (the engine operating under high load at a somewhat low RPM). I'm a bit surprised that it really got into that condition, because Ford's shift strategy usually drops you to a lower gear right away when that happens. Normally, a drop in filter will not produce this sound.

And, I just noticed you HAVE mounted larger tires. Effectively, you have reduced your gear ratio by doing so. That is going to hurt you badly while towing. About the only way to compensate would be to put the stock feet back on or, change your gear axle ratio - probably to 4.10 (both axles if you have 4WD).

And, Mcwilly, I've merged the two threads you started on this subject to this one here. Please don't start duplicate threads. It makes things confusing.

- Jack