Obviously there is something wrong with the electronic
rack and pinion. There is a torque sensor in there that
may have  malfunctioned. It sends data to the steering
computer (EPS) and the EPS then applies the appropriate
amount of polarity and voltage to the rack motor.
The torque sensor or EPS could be getting voltage spikes
from some of the other electrical devices in the
car. Perhaps the grounding wire is loose.

Get the dealer to swap it out and see if that
fixes it.

BTW Harley I will be needing new tires on my RX8.
I understand the ride on the tires you bought is much
better than the stock tires. Tell me again what brand
and size did you buy?

Evening, Paul....

Thanks for responding...

First, the tires.  This is my second set of new tires...both sets were
better than the originals.  Wore the Potenzas out in 14,000 slipping and
sliding miles.

Here's the tires I recently bought...1,000 miles and still love them!<G>
Only place I could get them was from Tire Rack.
http://tinyurl.com/y7t7sx
Even my mechanic commented on how good these Avon tires felt and was
surprised at the average life that is being reported for them (the new
tire tread depth is greater than normal tires).  He was impressed with
their traction on curves...they do feel a little softer, but very quiet
and smooth...probably because they are softer.

The first set of tires I originally replaced the Potenzas with, that I
also liked a lot (until my ex's mechanic recommended the Avon Tech for
her BMW) were BF Goodrich G-force.  ( http://tinyurl.com/y4fd7x ).  Got
26,000 miles out of them, and two were still barely above the wear
bars.  You'd probably have better luck finding those out there. Not sure
if there is a Tire Rack near you or not, as they have the added expense
of having to ship the Avon Techs to your installer. Although, being out
of state (for me) there were no taxes on them! Sales or excise.

I felt that either tire was far better than the Bridgestones ...
quieter, better traction, longer wear, etc....(and cheaper! <G>)

Now...my RX8....

>>there is something wrong with the electronic rack and pinion<<

That was my thought as well...but I discounted it as wouldn't that cause
the steering wheel to move if the front wheels move?  There is
absolutely no movement of the steering wheel at all.  I placed my finger
on the joint between the cover and the steering column while it was
doing this...couldn't feel a thing, and there was no visible movement of
the wheel at the same time, either drifting left, or when it
straightened out when the power was reduced...but the car changed direction!

Also I would think that something like that would be more
intermittent...this occurs dependably, every time, and at all
speeds...the faster you go, of course, the worse it gets.

But, if the front wheels can turn without the steering wheel showing any
movement, that may be the problem.  I'll see that he gets the info and
we'll see what happens.

Harley

Thanks for the tips on tires. I am still on the originals
and I hate the tire noise on concrete.

I think the torsion bar in the torque sensor is broken or
disconnected and the EPS is steering the car. Steer by wire :)