Truck isnt happy pulling trailer

[Westcoast]

What gear ratio? tire size? Mine has 3.55 and 285-65-18 and it can be a dog at times.

When towing it is ideal to be in 3rd (overdrive off) and have that torque converter locked up. When the TC is locked your transmission temps will stay much cooler. On a hill I will drop into 2nd and make sure my TC locks up vs. staying in 3rd unlocked. Its not worth damaging your tranny trying to tow in OD.

There is a setting on your Gryphon that will tell you what gear you are in and when the TC locks up. It almost sounds like you are shifting into another gear when the TC locks.

I hope this helps.

[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

[mcwilly]

My tow package gearing is 3.55's, unfortunately. My tires are 275/60/20's.
I've been trying to call PHP throughout the day but they must be pretty busy as my calls are going to their voicemail.
I guess what I found odd is that in the highest gear with overdrive off, it ran ~2500 rpm's, but with overdrive on, and one gear lower than overdrive, it ran the same speed at lower rpm's.

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.

Sorry about that. I posted in this section first before I thought it might get more views in the F150 section. I tried to go back and delete it but I guess the thread was too old by then for me to remove it.

Pic of the trailer:

[Jackpine]

It's possible you might have gotten more views in the F150 section, but I think it belongs here, and, once you create a thread (or a post), you don't have the power to delete it! (I expect that's because it can have a bearing on other posts in the thread.)

Anyway, glad you posted a picture. I suspect your trailer is 8 feet wide (standard width). Looking at the picture, it might be 7 feet high? (Box height, and 1 foot off the road?).

Now, with a class IV trailer tow package, the frontal area limit is 60 square feet. If your trailer is 8 x 7, you are at 56 square feet and very close to the limit.

Your tires have a 33" diameter (unloaded). If I were to mount your rims and tires on my truck with its 3.73 gearing and 32" tires, it would reduce my effective gearing to 3.62. I don't know what your stock tires were, but it's clear that your effective gearing is now much less than 3.55.

I'm guessing the empty weight of your trailer is 3-4000#?

In any case, I think you are very close to the tow limit of your truck. If you can afford it, changing your axle gearing to 4.10 would make towing a lot more enjoyable. (Both axles if you have 4WD).

Now, why were the RPMs in 3rd gear with O/D off higher than they were in 3rd with the O/D on? Probably, as Westcoast mentioned, your Torque Converter was unlocked in the higher RPM case. It would take very little additional load on the engine to cause the TC to unlock, which it does to provide you more torque. I think that at the speed you were traveling, your engine load is right at the "breakpoint". Again, higher gearing will help this situation.

And, if you want to talk to someone at PHP, try their "live chat" feature you can sign up for on their webpage. Their phones are ALWAYS busy and they really don't take phone "messages". But, if you keep trying, you'll eventually get through (you may become an old man first though).

- Jack

[Longshot270]

Just curious, have you tried using the comm gear PID while towing? One common misconception is the difference between 4th gear (overdrive) and 4th gear with the torque converter locked (locked overdrive) and then the locked/unlocked 3rd gear. Sometimes you think you are dropping out of overdrive and it is just the torque converter unlocking. Usually there is about a 400 rpm difference between OD and locked OD but could be more if you are towing. If your torque converter is locking just a bit too soon you can move that locking point back in your custom options menu.

[mcwilly]

Originally Posted by Longshot270

Just curious, have you tried using the comm gear PID while towing? If your torque converter is locking just a bit too soon you can move that locking point back in your custom options menu.

Seeing as I have no idea what you're asking, I'd say no I havent tried that. I've looked around the custom menu options but I havent made any changes. First thing I need/want to do is find out my tire size in mm so I can adjust that in the custom settings.

[Longshot270]

Originally Posted by mcwilly

Seeing as I have no idea what you're asking, I'd say no I havent tried that. I've looked around the custom menu options but I havent made any changes. First thing I need/want to do is find out my tire size in mm so I can adjust that in the custom settings.

You can use 2580 as a close starting number. To get it dialed in perfectly get a GPS and clear the odometers on it and your truck. Drive at least 10 miles and then use this little formula: GPS odo/truck odo X tire size (2580 if you program it in before you go).

To pull up the PID for the commanded gear go to settings, display, and then scroll through the list for "COMM GEAR", press enter. Then when you go back you'll see which gear the truck is currently supposed to be in. When you get up to highway speeds you'll see a little lock icon. That means that your torque converter is locked. Then next time you pull your loaded trailer look and see if having the shift/lock points raised or lowered would help. They move in increments of 1 mph because the part throttle shifting is dependent on speed and engine load. If having them raised or lowered would help then you can move them next time you reprogram your truck with the custom options menu.