Dale
   I can tell you from experience that the Audi problem was real. I

  don't know what the problem was but it wasn't small close peddles.
  I had an Audi and experienced an uncommanded acceleration.  Here
  is what happened.  I turned a corner on a city street and started
  to accelerate and the car throttle body went "Wide OPEN"  the
  RPM went   to about 6K.  I stood on the brakes and it was still
  accelerating
  and about to hit the car in front of me so I kicked the
transmission  into neutral and without a load the engine RPMs pegged
for a split  second and then dropped back down to idle.  I parked
the car on  the side of the road and called the local Audi dealer...
Keep in  mind it was "Not" under warrantee. They immediately picked
it up,  gave me a free rental and fixed it for free.  Oh, this was
the  4000S model and not the 5000 model car that was suppose to have
 the "Problem".  I don't know what was wrong with it but I do know
 it wasn't "peddles"

  Mike C.

  Not necessarily calling bs, but I don't get it.  There's not a car
  made that can accelerate as fast as it can decelerate.  That
  implies  that the brakes are able dissipate more energy than the
  engine can  deliver.  I believe the engine might have gone to WOT,
  but I have a  tough time understanding how the brakes wouldn't be
  capable of still  hauling the car to a stop.  One factor is that if
  the engine is at  WOT and you pump the brakes, the booster would
  quickly lose vacuum  and so you'd be without the brake assist. It
  might take a heavy foot  to get much braking effort, but the same
  braking power would be available.  And, I can imagine that it would
  be surprising as well..

  Matt-

  I have not tried it Matt but one can "fade" the brakes.
  This is when the pad material gets so hot the coef. of friction
  goes  way down. It is a runaway situation. The longer you hold the
  pedal
  down with full power the worse the brakes get. Also brakes boosters
  work on vacuum. WOT vacuum is near atmospheric pressure.

  Brake fade is very common in road racing. One of the first things
  you need to do to convert a car to a road race car is upgrade the
  brakes.

  Paul Lamar

  --
  I doubt my situation caused any brake fade as it was over in less
  than 5 sec... I was on a 30 MPH zone and only about a car link and
  a  half from the car in front so by the time I stepped on the brake
  the
  distance was closing very fast and I immediately went into
  neutral... It was over very fast,... I remember starting to change
  direction toward the curb to steer around the car as I threw it
  into  neutral... No Idea what caused it but it was real.  Not that
  the  following has anything to do with the "Audi issue" but for the
  Prius
  problems... I personally think that there might be some EMI
  issues... They certainly don't shield those cars or test them to
  the  level we do in Aerospace and I bet they have missed a corner
  EMI  condition... Which would explain the "Ghost" in the system.

  Mike C.

  In a road racing situation the brakes can fade in a fraction
  of a second. You come into a 20 MPH corner at say 80 MPH (117 FPS)
  and stand on the brakes.

  The brakes can fade in 100 feet. Of course if you did not
  brake then that cannot happen. That scenario is for those people
  that tried to stop the car by applying the brakes.

  Paul Lamar

  Trying to back out of a parking stall and putting it in reverse
  says brake fade was not an issue. Mike's problem could be
different.  A lot of heavy brake use precedes brake fade. Three laps
of the old  Edmonton International Speedway
  (remember that one Paul. I corner marshalled a few times when the
Chapparal was there) and my RX 3 had no brakes. 130 MPH into corner
one. Yah it can happen quickly, usually on a heavy car and a down
hill. Drag racers used to brake torque to warm the rear tires. Held
the brake to the floor and the gas pedal to the floor. They usually
backed off the rear brakes a bit so they did not hold as well. Then
they could really melt the rear hides. The front brakes still held
 the car back. I still say the brakes SHOULD hold the car back. I
could see some creep, but not the unimpeeded acceleration described.
 If this did happen, the brakes should be really hot when the car
comes to a rest at the end of the event.

  Dale Davies

  I think the term unintended acceleration applies to a wide variety
  of situations. I agree that from a dead stop the brakes should hold
  the average car from moving as there is no real energy going into
  the brakes. The lady in the parking lot could be faulted for not
  putting
  her foot on the brakes when she selected reverse but how many
  of us really do that all the time?

  Paul Lamar

  With an auto trans??? Aways!!!

  Dale Davies

Modern cars with autos TX won't let you get out neutral without your
foot on the brake.  The gear selector is locked.

Matt-

Maybe that law suite caused that change. That happened years ago.

Paul Lamar

One problem not mentioned so far is that almost all current vehicles
have ABS.  This on/off/on cycling during a hard stop must generate a
great amount of heat which I'm sure has been compensated for by the
manufacturers.  But have their design parameters considered the
addition of full power applied during the stop?

Joel

Back in the old days GM used to test auto tranies by jerking
them into reverse at maximum burn out :) Roughly 30 MPH.

If it survived six of these in a row it was deemed
good to go.

Paul Lamar



Joel,
You have to remember the ABS only cycles the brake pressure when the wheel
sensor(s) sense imminent wheel lockup. The drive wheels in this instance will
keep turning. Lots of heat quickly. People need to keep their wits about them
under all circumstances. If this happens, turn the key OFF one position!! If
you only go one position the steering should not lock. Could be difficult when
you are filling your pants.

Dale Davies