hauling 3,500 lb trailer and 9,000 lb payload uphill
 

i have a 2005 Ford F-350 super duty turbo deisel, when do i use the "haul/tow" feature. my driver just came back to vegas from CA, he could not go faster thatn 35-40 uphill. but he did not know or engage the "tow/haul" feature. pls tell me that will help. jack

I could tell you that will help, but I'd be lying. If he had the accelerator floored the tow/haul feature won't do anything to help. The truck is at it's limit and that's all the power it has. Tow/haul does not add horsepower.

Did he manually downshift to third? That's what them gears are for.

If he had his accelerator on the floor manually shifting won't help. The trans will already be in third gear.

I assume that's a 6.0 diesel. 12,500 lbs isn't that big a deal for that motor. And once your through the Cajon Pass there isn't a significant climb.

Has the truck been serviced recently?

I never had that problem on the Cajon with probably 13 k behind me. I could hold 60 with my old 05. It was totally stock.

Tell him to use tow/haul when towing or hauling. DUH!

Tell him how to operate the long, skinny pedal.
I asked a guy, with a similar performance issue, if he had it floored and got a stupid look.

If the horsepower is indeed low, fix the truck. My bet, turbo issue.

Yeah, but that's the only significant climb between LA and LV. I towed it with my '07 but the trailer was only about 9K lbs. No issues. It climbed it just like the Grapevine.

Assuming the driver wasn't out to lunch it could indeed be a turbo going bad. I did see a friend's 6.0 that had so many hose leaks that it wouldn't make much boost. We put hoses and clamps on it and it was right back to normal. He had been driving it that way for months thinking its just another 6.0 slowing dying.

I'm wondering what type of EGT's he was having, and how much damage happened. Definitely something not right...

This would prob get more help in the 6.0 section. This is the 6.7 section and power is not a problem here.

Never had power issues with my 6.0 - something doesn't sound right. Granted this was back in 2005, to going on 13 years now since I last towed with one. Our resident Ford Transmission Engineer has already chimed in about tow/haul. I'll add some end user language though - Tow/Haul just changes how the transmission shifts, you can use it empty or loaded. Loaded I always use it - certainly helps in the stopping department - as the transmission holds the gear longer. (usually that's when I notice I forgot to turn it on on those occasions I forget)

Get it checked out. If it's bone stock and never been bullet proofed, you may be looking at some repairs (and I'd bullet proof it then too).