Downhill surging

[Flourman]

Made my first trip up the mountains (without trailer). I usually put my trucks in tow/haul coming down so I’m not riding the brakes as the forest roads can run 10 degree plus grades in some portions.

I did the same today and it downshifted as I had hoped but then when it downshifted to third, it seemed like the truck was surging a bit. It would last maybe 2-3 surges and then even out. Granted, I’ve only got 280 miles on it so it could be the transmission learning what to do.

Has anyone else seen this happen?

 

[JDP]

I'm curious because I want someone to educate me, couldn't you do the same thing by just using the manual shifting instead of the tow/haul. In other automatic transmission vehicles I usually just shifted out of drive and into a lower gear when descending from ski slopes and such.

 

[DwnSth]

Made my first trip up the mountains (without trailer). I usually put my trucks in tow/haul coming down so I’m not riding the brakes as the forest roads can run 10 degree plus grades in some portions.

I did the same today and it downshifted as I had hoped but then when it downshifted to third, it seemed like the truck was surging a bit. It would last maybe 2-3 surges and then even out. Granted, I’ve only got 280 miles on it so it could be the transmission learning what to do.

Has anyone else seen this happen?

Are you using your engine break?

 

[Flourman]

Are you using your engine break?

It’s a 7.3. I’m letting the engine do as much braking as possible.

 

[Tx-Tremor6.7]

Are you using your engine break?

Does he have an engine/exhaust break? He does not mention his engine in his post or his signature...

I towed my 9500 lb TT up and down 6-7% grades on the way to Yellowstone and I did not experience surging while going down hill. I have a 2021 with the 6.7L so I was using tow haul mode and the exhaust brake in auto mode.

 

[Tx-Tremor6.7]

It’s a 7.3. I’m letting the engine do as much braking as possible.

The 7.3L does not have an engine/exhaust brake, but the 6.7L does have it.

 

[Flourman]

I'm curious because I want someone to educate me, couldn't you do the same thing by just using the manual shifting instead of the tow/haul. In other automatic transmission vehicles I usually just shifted out of drive and into a lower gear when descending from ski slopes and such.

I started just using tow haul (going downhill, unloaded) with my F150. A little tap of the brake and it downshifts. It makes descents way easier.
Also a little tip for those washboarded forest roads, put the truck in 4x4 and it runs through those so much easier. You don’t need the traction but having the front pull vs just the rear pushing on this washboards makes them a lot smoother.

 

[Flourman]

Does he have an engine/exhaust break? He does not mention his engine in his post or his signature...

I towed my 9500 lb TT up and down 6-7% grades on the way to Yellowstone and I did not experience surging while going down hill. I have a 2021 with the 6.7L so I was using tow haul mode and the exhaust brake in auto mode.

It could be the computer just learning how to handle the grade shifting. I don’t have even 500 miles on it.

 

[DwnSth]

Made my first trip up the mountains (without trailer). I usually put my trucks in tow/haul coming down so I’m not riding the brakes as the forest roads can run 10 degree plus grades in some portions.

I did the same today and it downshifted as I had hoped but then when it downshifted to third, it seemed like the truck was surging a bit. It would last maybe 2-3 surges and then even out. Granted, I’ve only got 280 miles on it so it could be the transmission learning what to do.

Has anyone else seen this happen?

Sorry. Must be a 7.3 thing. I miss spoke if you do not have a engine break.