One thing to try is to disconnect everything electronic associated with the steering. It doesn't matter which circuit or system it is, adding a computer to it greatly increases the cost, diagnostic time, unreliability, and frustration, but the engineers have somehow determined that's what we want. With the electronic portion disabled, treat the steering just like on any other car. It would be helpful if you would post the readings for "caster" and "camber" for both front wheels. Normally caster is not adjustable on front-wheel-drive cars because it has such little affect on pulling compared to on rear-wheel-drive cars, but still, as it increases, steering effort gets harder. That is what provides the road feel and stability too.
Unequal caster, which causes a pull on rear-wheel-drive cars, can be offset by a similar offset of camber. While the car will go straight on level roads, the two tires will be pulling equally in opposite directions to offset each other, but for different reasons. (Think of putting a ten-pound weight on your right shoe, and a ten-pound weight in your left hand. You'll be in balance as long as you're standing still with your hands to your side). Your steering will be in balance as long as you're on a level road with no bumps. No roads are level. Most slant down to the side you're driving on so rain will run off.
Since caster is non-adjustable on your car, if it is not equal on both sides, the mechanic may need to adjust in a little difference in camber to offset it. While that can make the car go straight most of the time, you'll still have a higher steering effort in one direction. (In this case, think of a 50-pound child at the end of a teeter totter, and a 100-pound person halfway out on the other side. That will also be in balance, but to move either one of them individually, it would take more effort to move the 100-pound person up and less effort to pull him down).
I'm not sure what you mean by "bias". If you're experiencing a difference in steering effort from one way to the other, observe how the steering wheel returns too. When caster is unequal, you will typically find, (for example), the steering wheel turns easier from centered to the right than from centered to the left, but you would also find it RETURNS from left to centered easier than from right to centered. If you find it turns harder from centered to the right AND from left to centered, that points to a problem in the rack and pinion assembly.
Other things to consider are a tight ball joint and binding upper strut mounts. Most of the time those just cause harder-than-normal steering at all times, but that can be aggravated by having more weight on one side of the car.
Tuesday, December 2nd, 2014 AT 3:54 PM