fully boxed frame providing a 70 percent improvement in torsional stiffness. Heavy Towing versions received a heavy duty 9.75" Rear Differential and Axle combination compared to the 8.8" of the standard version. Along with the high towing capability came all-new steering, braking and electronic systems to help the Expedition better control and maneuver long heavy trailers. Adaptive variable assist power rack-and-pinion steering was introduced along with the largest brake rotors in the segment at that time ( up front, in back) with brake calipers 100 percent stiffer than the previous generation Expedition. The four-speed 4R70W automatic transmission received all-new control software to allow the transmission to automatically adjust to the demands of towing, using new computer logic that recognizes changes in load and road conditions. The automatic full-time ControlTrac four-wheel drive system remained available, with an uprated two-speed dual range BorgWarner 4416 transfer case. The new transfer case featured an updated intelligent locking center multi-disc differential with front-to-rear "torque biasing" capability in Auto mode. A new dedicated microprocessor with new control software was added allowing the system to detect different terrain and surface conditions to predict traction loss before it happens. Two High mode was also reintroduced. Four-wheel electronic traction control was now available as an option, and simulated front and rear differential locks. The V8 engines offered on the previous generation were carried over, but not without major changes and improvements. Both the 4.6 and 5.4-liter Triton V8 engines received further refinements in design and overall efficiency. Expedition qualified as an Ultra Low Emission Vehicle (ULEV) and was certified under the Environmental Protection Agency Tier 2 regulations one year earlier than required. The 4.6-liter engine received an all-new redesigned cast aluminium engine block optimized for weight reduction and NVH improvements. The 5.4-liter engine received an all-new redesigned cast-iron engine block with computer designed ribbing and bracing, along with thicker side skirts and reinforcement at the oil pan flange. The new engine block helped reduce engine vibration and unwanted noise while providing refined performance. Both engines featured piston skirts coated with a teflon-based friction-reducing material, and fitted with low-tension, low oil consumption rings. In addition, a new fail-safe cooling mode provided protection even in the case of a catastrophic coolant loss (such as a punctured radiator). In the event of coolant loss, the engine control unit shuts off fuel to alternate cylinders to reduce the risk of engine damage from