Expedition 2019 Platinum 4A mode really "auto" or is it actually 4H?

[rd618]

Here's what really bothers me about this mode though. When you put it in SPORT mode it automatically shifts to 4A sending power to the front EVEN ON THE INTERSTATE. To me, SPORT mode should just adjust the transmission or maybe even fuel to give more power/sportier feel. But Sport is actually an "offroad" mode I guess to Ford.

It does that to prevent wheel slip.
On my 22 if you put it in sport and put it in 2H I can break the rear tires loose. In 4A the front hubs engage somewhat so no loss of traction.
On the interstate it prioritizes rear tires with low transfer to front. It can adjust the amount of torque front axle gets in 4A.
4H (which I have in 22, but you don’t in 21) locks the center clutch packs as tight as it can to send equal power front and rear. You can engage a similar mode if you select sand or mud and ruts.
4L is the same as 4H, but with the 2 speed transfer case switching to higher numerical gear ratio.

 

[dtximages]

It does that to prevent wheel slip.
On my 22 if you put it in sport and put it in 2H I can break the rear tires loose. In 4A the front hubs engage somewhat so no loss of traction.
On the interstate it prioritizes rear tires with low transfer to front. It can adjust the amount of torque front axle gets in 4A.
4H (which I have in 22, but you don’t in 21) locks the center clutch packs as tight as it can to send equal power front and rear. You can engage a similar mode if you select sand or mud and ruts.
4L is the same as 4H, but with the 2 speed transfer case switching to higher numerical gear ratio.

I understand it's to prevent wheel slip but that's never an issue at interstate speeds.. I might understand only at launch. The point is that 4x4 is constantly locked-in in 4A where I don't think that's the case with other brands.

 

[sjwhiteley]

Not seeing the problem, here. 4A seems appropriate. It automatically applies 4A when needed. If you are in 'sport' mode, the likelihood of needing more traction is increased, so applies some to the front wheels, as well as the rear. It's not 'locked in' as it can change based on requirements.

I don't have 4H, but would likely run 4A in all but the most aggressive off-road conditions. 4A does great in mud, snow and dry conditions, and responds appropriately and efficiently.

 

[rd618]

The point is that 4x4 is constantly locked-in in 4A

This is where you are wrong. 4A is never “locked” unless you’re in a specific mode. As I mentioned above.
4A adjusts the torque to front and rear as needed.
Could be 10%, 25%, 50% etc to front. Not like that gauge on the dash is accurate. Just an image people get an “idea” about what’s happening.
If you want 0% going to the front. Turn off 4A and put it into 2H.
By you selecting 4A you’re telling the truck “I want some amount of potential torque going to the front”.

 

[dtximages]

Thanks, maybe I have always been wrong about what 4A really meant then. I thought it literally meant 2H until slippage is detected then it immediate activates the front axle. Now I'm learning there was always some power being sent to the front.

But if it's considered "smart" I don't understand why it would ever send power to the front while driving 70mph+ on a dry interestate under mild accelleration.

 

[rd618]

Thanks, maybe I have always been wrong about what 4A really meant then. I thought it literally meant 2H until slippage is detected then it immediate activates the front axle. Now I'm learning there was always some power being sent to the front.

But if it's considered "smart" I don't understand why it would ever send power to the front while driving 70mph+ on a dry interestate under mild accelleration.

What you’re describing makes sense. There are many other systems that do exactly that. But normally you don’t get to select the modes. Explorer is a good example.
For the expedition it has the ability to send 0% up to 50% to the front axle while in 4A. I however do not know when it sends 0% front and what conditions would motivate that behavior.

 

[xmountaineer]

I’ve only owned my 19 max (with the hd tow package) for about a month but so far I must say that I am not overly impressed with 4A. I live on a gravel road and my driveway is also gravel, long, somewhat steep in sections and has one big turn going up the hill. This section is definitely not steep. I engage the gravel/grass/snow mode before getting on my driveway. When I go around this turn about half the time the traction control light comes on and the power gets cut way down. I’m going no more than 10mph. It never feels like the front tires grab. There should be no way that the traction control light should come on in this situation if 4wd was truly working. At minimum the elsd should kick on, right?….and front tires should pull me up. Next time I’m going to put the power distribution graphic on the display and see what happens. I engaged the elocker one time and won’t ever do that again going around that turn, it seemed like it struggled even more, likely because of the turn. I can zip right up my driveway with a front wheel or awd vehicle with zero traction issues.

 

[Rob6805]

I’ve only owned my 19 max (with the hd tow package) for about a month but so far I must say that I am not overly impressed with 4A. I live on a gravel road and my driveway is also gravel, long, somewhat steep in sections and has one big turn going up the hill. This section is definitely not steep. I engage the gravel/grass/snow mode before getting on my driveway. When I go around this turn about half the time the traction control light comes on and the power gets cut way down. I’m going no more than 10mph. It never feels like the front tires grab. There should be no way that the traction control light should come on in this situation if 4wd was truly working. At minimum the elsd should kick on, right?….and front tires should pull me up. Next time I’m going to put the power distribution graphic on the display and see what happens. I engaged the elocker one time and won’t ever do that again going around that turn, it seemed like it struggled even more, likely because of the turn. I can zip right up my driveway with a front wheel or awd vehicle with zero traction issues.

Try the mud/ruts mode next time. I believe this is the one that creates a true 50/50 split like conventional 4H would.

 

[chuck s]

Based on my experience with two (2) Gen3 Expeditions I can state 4x4 is certainly "locked in" in 4A. I can feel the engine load change when switching into and out of 2H and 4A when driving at a constant speed on on level, dry ground. Engine is working minutely harder. For that reason I do not run it as a normal setting. "Pretty sure" -- meaning "I don't know" -- all this is the center differential engaging and disengaging, with the front axle being a dumb axle.

Gen4 guys give this a try and see if you can feel something.

I have 2H, 4A, 4H, and 4L available and rarely run in other than 2H.

-- Chuck

 

[balthisar]

Try the mud/ruts mode next time. I believe this is the one that creates a true 50/50 split like conventional 4H would.

And also he can look at the power distribution screen and actually see when and under which conditions power is routed to the front. 4A really, really isn't 4H.