wwest

And Ford's answer was/is...??

Haven't driven one, don't own one, don't plan to. But. Partially engaging the rear drive while turning might very well result is rather strange handling dynamics on an adverse, slippery, roadbed surface. During low speed acceleration, straight ahead, no real problem except for premature (<100,000 miles) failures within the drive train's weakest link(***) due to drive line windup and/or tire scrubbing. *** PTO for Ford, Transaxles(TC lockup clutch) for Acura MDX.

The new FWD or F/awd 2011 Ford Explorer cools the PTO/PTU using engine coolant. Perhaps you could get Ford to retrofit the 2011 Explorer's PTO to your......

Yes, most F/awd systems, Honda/Acura's SH-AWD only exception, are patently UNSAFE in the very conditions for which many of us shop/purchase them. Perfectly fine, admittedly even better than RWD or even R/awd, unless you find yourself in climate or roadbed conditions that are marginal.

Your best bet is probably to simply pull the rear drive clutch fuse at all times other than when you actually need AWD traction. It is likely that the PTU lubricating oil is boiling, compromising the seal, due to the PTU heating level from operating in AWD mode. The Mazda CX-7 uses engine coolant to cool the PTU in order to avoid this very problem.

"...consider how AWD operates...." Which AWD type..? Base FWD therefore F/awd, or base RWD therefore R/awd..? And even beyond that, there are a myriad of F/awd and R/awd designs out there in teh marketplace today. But think of why truckers are always required to have rear drag chains on the rear most axle of their trailers.... So if you MUST use tire chains they should always go on the REAR first. So if you have a FWD or F/awd vehicle then for safties sake you should NEVER have tire chains ONLY on the front.

EcoBoost, TWINFORCE = horribly poor FE 99% of the time in return for STELLAR 0-60 times. Turbo lag is lowered by exhausting some of the energy of combustion into the exhaust manifold to spool the turbine up more quickly. Eliminate the turbo and raise the compression ratio to a level cognizant with DFI, ~12:1, and get good FE 99% of the time. Even better.... Adopt Toyota's new e/VVT-i technique to shift the engine mode between Otto mode and Atkinson mode. ~15:1 CR for low to moderate throttle openings but ~12:1 (DFI) for WOT. Or even better... West/Otto/Atkinson/Miller multi-mode engine using e/VVT-i along with a variable volume (Toyota's HSD CVT/PSD) positive displacement SuperCharger to eliminate the throttle plate and provide BOOST ONLY at WOT. West/Otto/Atkinson/Miller Multimode....15:1 CR (Otto) >>> 15:1 CR (Atkinson, 13:1 effective) >>>/10:1 CR (Miller, 15-18:1 effective {full BOOST}).

Google for: wwest hesitation abolition -dfg

Given the absolutely HORRID (in comparison) FE the TwinForce ("EcoBoost") engines are running I suspect Ford might be busy retooling their thinking on this. A 4 cylinder engine, even or especially with DFI, will be somewhat short on HP/Torque to begin with, now detune/derate it to accommodate the turbo and it will simply not be appropreate for anything larger/heavier than the old Pinto SW. On the other hand anormally aspirated 4 cylinder with DFI (12:1 CR) would likely yeild STELLAR FE along with quite reasonable HP/torque for the Edge.

And the REAL answer is... Real time control of the ATF line pressure. In most modern day vehicles the ATF line pressure is "relaxed" allowed to decline to a fairly low level, pressure only as needed and only at a level currently required. When a shift is required, especially a quick return to acceleration just after an upshift due to entering cruise mode, the engine will be held at idle until the variable displacement ATF pressure pump can be moved to a high volume (HIGH pressure) position, and line pressure can build up to the higer level required to provide the downshift AND hold the downshift clutches TIGHTLY. Think of the old constant volume power stearing pump, horrible waste of fuel to pump VOLUMES of fluid pressurized to 3000PSI only to dump it back into the sump. The new ATF variable displacement pump with real time pressure control system only pumps the volume of fluid required of the moment and has no method of predicting the future.

"...built on a Friday.." No, the entire R/awd system was commited to final design on a "Friday".

"..I have a Twin Scroll Turbo on a 1.8L motor.." But did you lower the 1.8L engine's static/native compression ratio in order to take the most advantage of the turbo BOOST..?? The static/native compression ratio for a DFI engine should be in the range of 12:1 for optimal crusing FE.

"..it down shifted.." Maybe...or maybe not. You may have just simply released the lock-up clutch. In the name of improved FE the "OD" lockup clutch is now being used in gear ratios below the actual OD gear ratios. In addition to that some of the new 6(9) speeds, when coupled with a "strong" V6, have 2 OD gear ratios.

"...nearly impossible..." And that spells the difference. Loss of traction on the drive wheels of a RWD vehicle leaves the driver in "control", whereas with FWD or F/awd......

Our DD is an '01 F/awd RX300. Prior to that was a '00 F/awd RX300, before that a '92 Jeep Cherokee Limited AWD/4WD/4X4 and before that was an '85 Jeep Cherokee Limited. The '92 Jeep is still doing stellar duty on a north central MT cattle and wheat ranch. The '01 F/awd RX300 has wheel spacers so that rear tire chains can be fitted first and then the fronts added if/when needed. Otherwise it runs all year around on nice and quiet, comfortably riding, Bridgestone Turanza summer tread tires.