Hey Freak, did they find anything out? This is definitely a problem. My '05 kicks in the rear almost immediately, and I've personally experienced one of three things. Either I'm really stuck, and both front and back dig a hole. Or I easily move on, or the back end is kicked out.

Of course when the back end kicks out, it's because I wanted it to.

 

Your going to get rear wheel torque no matter if your on snow or a perfectly dry pavement and more if the system detects front wheel slippage as that's the way Ford's UnIntelligent 4WD System is "supposed" to work. I personally haven't seen that increased rear wheel as of yet. I haven't seen that increased rear wheel torque under full throttle that they mention yet either.

 

Perhaps that depends on the terrain and the load the rear wheels are under. If the weight bias is shifted to the rear, then I think you would "feel" it more. I live in Utah and our Escape is driven off road up vertical trails weekly if not daily. I can go up a grade, lean out the window and see almost all of the power directed to the wheels.
I also use Michelin AT-2 tires that are pretty aggressive. The LRR tires that came on it were junk in the snow. I really don't concern myself with mileage anymore since when we do drive on pavement, it's 97% highway speeds since we are rural and most speeds are above 50 and in ICE mode.

 

The system in theory can only send 50% pulse width modulated 12V to the clutch in the rear. If you go above 50%, you'll start to have steering control problems. A function test from the Ford WorkShop Manual has the tech command 100% rear wheel torque and if it resists turning, it's working properly.

I have a Scanguage-II coded to show rear wheel torque. It's impossible to leave from a dead stop without having rear wheel torque. Floored from a dead stop on dry pavement never shows over 35%. Normal acceleration is always >20%. So if you always get something, you get that on snow. I've never seen any increased rear wheel torque on snow not that it hasn't possibly happened, I just never seen it yet. Leaving from a dead stop on snow is where you'd really need rear wheel torque but you get it then no matter what the road conditions are. The big question is, do you get more then?? I should see >35%.

 

Interesting. So then it is limited to 50% max electronically to the rear end? And also, is it then limited to 25% of total to left/right?

 

Yes, 50% max. There is no left/right so to speak, it's only back/front, meaning traction control can pulse the brake fluid pressure to a certain wheel not sure what the percentage would be. TC wasn't available on the FEH till '09 though.

The Accura SH-AWD system has a clutch at each wheel.

 

That's why I didn't buy a 2008 FEH when I checked them out.

 

The front diff'l input is SOLIDLY coupled to the transaxle output drive.

Absent a bit of "overdrive" on the rear driveline, as the SH-AWD system has (7%..??), no more than 50%, 50/50 coupling F/R, is possible.

Does the 35% equal the maximum PWM duty cycle or the maximum rear drive coupling level...??

35% PWM maximum might/could mean completely HARD rear coupling which would yield 50/50 F/R.

 

"..I've never seen any increased..."

"..do you get more then.."

NO.

The way I read the documentation if the rear coupling is at the 35% PWM, and that isn't enough to prevent wheelspin/slip, then TC INSTANTLY activates, begins using braking to abate wheelspin/slip while also simultaneously dethrottling the engine.

 

The documentation on what states 35%? If you refering to the Ford system and 35% is max then the system doesn't work as described in Ford manuals. Normally you get some rear wheel torque all the time and if front wheel slippage is detected your supposed to get more.