NASA Scientists to Test Toyota Electronics
http://abcnews.go.com/Blotter/nasa-s...ry?id=10241757


The brake vacuum system can't handle a classic
pedal misapplication situation., or so I hear.

Word on the street is that the unintended acceleration
is real, not entirely customer induced. The fault sequence
I believe, goes like this.

After the third or so hard application of the brake pedal in quick
succession, the brake vacuum has been exhausted. Once
the vacuum is exhausted, the pedal will become hard
and the brakes ineffective until the pedal is released to
build vacuum.

If a customer hits both pedals at the same time, a typical
pedal misapplication, an extended holding of both pedals
will result in the brake vacuum falling, and the throttle
quickly overcomes the brakes. In addition, with an
open throttle, intake vacuum also normally drops
significantly.

The reason an operator doesn't simply release the brake
pedal for a moment to restore normal operation is due
to the normal operator response to getting your foot
stuck in both pedals. It just happened to me last week
in a rental in downtown Atlanta. I misjudged the
position of the brake pedal while stopping, so I hit
the throttle too.

The reason it's so difficult to release either pedal is that the car
is /already in a situation/ where it needs to slow down, hence
the switch from throttle to brake pedal, and even letting up
for a second would mean the car jolts ahead and right into the vehicle
in front of you. You can't release, the only way I avoided an
accident was the car slowed (a Chrysler) with both pedals floored,
as it should, giving me time to think about it and slip my foot
to the left.

But there was no way I could release either pedal
in that situation without hitting the car in front of me.
So in this case both pedals would remain floored until the car
hits something.

In a pedal misapplication situation, if the brake vacuum is lost
too soon, the operator would only have a few seconds
until the throttle wins.With an accident being almost certain.

Should be all kinds of ways of fixing this problem. From electrically
or engine operated vacuum pumps, to a larger booster etc.



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