All you really need to know is that AYC is the reason everyone who drives an Evo appears to drive like Tommi Makkinen, and Mitsubishi has finally deemed the car-loving citizens of the United States worthy of the system. That of the Evo X is considerably more advanced than in previous iterations, though. The new system will work in tandem with EBD (something more traditionally used to regulate vehicular yaw moment) to squash understeer. It does this using yaw rate sensors and by detecting brake fluid pressure in the lines.
The AYC brain now talks to the engine, too. Well, it listens at least-to engine torque and speed. Mitsubishi says this connection allows the system to determine what the driver wants from the car and provide that output quicker than earlier systems.
Picture a novice driver understeering hopelessly into a corner. His first reaction is to crank more lock into the wheel. Using a steering angle sensor, the system can tell what the driver is trying to do, and then assess whether the car is actually doing it. The electronics may be laughing at your crappy technique, but they'll get the car turned anyway.
The options go unchanged from Evo IX to Evo X, but their effects have been expanded.
The Other Bits Of S-AWC
AYC wouldn't work at all, were it not for Mitsubishi's ACD, which works to control the speed differential between the front and rear wheels. But the term "center differential" is misleading, because the unit that controls this is actually inside the transfer case at the front of the car, not the transmission.
Two shafts protrude from the transmission, one inside the other. These send torque to the transfer case, which also houses the front differential. Bolted to the front differential housing is a ring gear, which connects to a pinion gear that then sends torque to the rear wheels. Confused yet?
Instead of a viscous coupling (as found on non-ACD Evo VIII's), there are hydraulically actuated clutch packs inside the transfer case. Depending on the ACD settings, these clutches try their best to make all four wheels spin at the same speed, even if it means locking the output of the center differential and creating a 50/50 torque split. These are what you're adjusting when you switch between "Tarmac," "Gravel" and "Snow." It's important to note that the center differential is actually open on an Evo, which means that there isn't a set torque split, per se. If the ACD is fully engaged when two wheels are on ice and the other two are on pavement, all four wheels will spin at the same speed. That means that power can be sent purely to the wheels that areon pavement.
Compare this open center differential to that of the Driver Controlled Center Differential (DCCD) on a Subaru WRX STI, which has a mechanical torque split. When you turn the dial, you can actually feel more torque being transferred to the rear wheels during driving. This is only possible by coincidence in an Evo-if the rear wheels have more grip than the front wheels, the ACD will send more torque rearward until all four wheels are spinning at the same speed.
In addition to the new AYC and ACD systems, the Evo X adds stability control-this system detects under or oversteer resulting from abrupt steering inputs and works to eliminate wheel slippage. A traction control element regulates wheelspin during acceleration. Both systems work in tandem with EBD to only silence the wheels thatare slipping.
Things That Make The Evo Go Fast
Even though Evo's VII through IX used the newer CT9A chassis, they still shared a key common element-Mitsubishi's venerable 4G63 engine. Like everything else in the Evo, it evolved, eventually ending up with MIVEC (think Mitsubishi's VTEC) and a titanium turbine wheel. But, as Mitsubishi explains it, an engine that returned excellent gas mileage and clean emissions was necessary to take the car into 2008.