Do some research on the topic of torque management and I think you'll find your answer.

 

my truck only spins when I power brake...

 

You can hit your traction control button once to "disable" traction control, which really doesn't do much. If you hold the button for 10 seconds, it should disable advancetrac and then you should notice a difference.

 

Traction is the key to victory. My 3.31's spin the tire...And it's a 5.0. I'm also not ready to buy new tires, so it only happened once or twice.

 

The way I look at it if your spinning the other guy is winning. My 05 5.4 with 196k+ on it can still spin the tires when I stomp on it.

 

If you double tap the traction control button it turns into "advance trac sport mode!!" Have fun!!

 

Lit mine up the other day while making a right..... Dead stop, wimpy 5.0 and 3.31 gears.....

Prolly won't do it again. Tires are spendy.

 

I do that for fun and spin tires at any time. 5.0 with 3.31

 

Maybe something with the 2015s. My new 2016 wants to bark the tires all the time. In fact, when giving it throttle to pass someone, I accidentally gave it to much (still learning that this thing has incredible power), and barked the tires at 35 mph when it downshifted.

The Ecoboost 3.5L I test drove didn't spin the tires as easily and it still had the 3.55 locker while mine does have the 3.73 locker.

With the weight to power ratio, even with 3.31 gears, spinning the tires shouldn't be a problem. I haven't seen to much torque management yet, but I haven't got into the throttle at stops. Hek, it barks the tires when I'm trying to take it slow. Much more power off the line and up in the rpms, than my previous 2012 F150 that was configured the same as the 2016.