duneslider
Full Access Members
I noticed this too. I don't like that it applies the brakes, at least as much as it does. I can't tell if it also applies the trailer brakes as well but I assume it does. IMHO it stayed on the brakes far too long for my comfort. Trailer drum brakes just don't handle prolonged braking like that very well.
We did Raton Pass this year going to/from CA. Good times.
I took off cruise control but the default shifting while in tow-haul was not restrictive enough for me and I'd steadily gain speed, requiring frequent brake applications. I started manually downshifting using the + and - buttons and usually had to drop 1-2 gears beyond where the computer had it in order to hold downhill speed. I tried to keep it no more than 3300 rpm.
Overall I'm a little disappointed in the downhill experience. I like that if you tap the brake it'll often drop a gear, but it seems to not do it beyond 2500-2800 rpm, which on the steeper grades isn't enough. And yes I slow down before the descent.
Is it bad to let it rev at 3500 rpm for extended downgrades?
That is interesting, there weren't a lot of really steep long grades on my recent trip, so I will be curious to see what it does when I do some of those. I felt the engine/transmission was doing a good job holding it back. If I braked a little it would down shift to match that speed and then hold it pretty good at that speed until I pressed the gas.
I wouldn't think there is any issues with the engine at 3500rpm while holding the load back, that is the engine holding it back. That is what I would experience in a manual transmission truck while engine braking. I am not 100% certain how these nefangled direct injection computer controls everything engines work in this case but typically it when you let off the accelerator it closes the thottle body valve which creates a vacuum and slows fuel delivery and the engine is trying to suck air which causes the drivetrain to slow down. In typical automatic transmissions it basically just freewheels/coasts but if the transmission programming can keep it engaged the vehicle will slow down or maintain a speed (depending on programming). That all said, the programming still might not be perfect since it can't see what you can see (tight turns, winding roads, traffic, etc.) Either way, the expedition auto transmission seemed to handle things better than any other automatic I have ever driven.
What year is yours? I heard the 2019 programming was better than 2018 and I heard you could take the 2018 in for a reflash and it would improve.