Auto ECU's use the sensors to control fuel according to the
voltage supplied by them. Most sensors output 1 to 5 volts. More
volts is more fuel. The new drive by wire open the throttle
according to the throttle position sensor. That is also trimmed by
the traction and ESC controls built into the software.   The O2
sensors are different in that they only operate on .1 to .9 volts.
They generate this voltage in response to the O2 in the exhaust. The
ECM is trying to maintain an A/F ratio of 14.7 to 1. This coincides
with a voltage of 0.5. Diagnostics have an output of cross counts
which is the number of times per second this voltage crosses the
0.5V's. A high number (cross counts) is desireable for emission
controls. As with other sensors, more fuel translates to higher
voltage. The ECU then shortens the pulse width,
(gives less fuel) to respond to the excess fuel in the exhaust. An
O2 sensor that has low cross counts is due to be replaced. Fuel
economy will likely be improved. O2 sensors SHOULD not have anything
to do with the throttle position stepper motor. As with any man made
device, anything can and probably will go wrong.   A few years ago,
 Audi had a lot of trouble with the UNINTENDED ACCELERATION
PHENOMENOM. One of the car magazines did some reasrch and found the
fault to be small close pedals that low time (new owners) mistook
the gas pedal for the brake pedal. In each incident the owners were
positive they were stepping on the brake. The magazine testers were
the same as the new owners that had their car take off. ALL CARS ARE
DESIGNED WITH BRAKES THAT CAN HOLD THE CAR BACK. Modified vehicles
MAY be an exception.   In the expert witness case, the driver could
not have had their foot on the brake pedal firmly when they put the
vehicle in reverse. If it had been so the vehicle may have moved
slightly, but not enough to kill anyone. IMHO.

Dale Davies

--
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.


Mike
I just re read this and must relate an incident years ago while working at a
Nissan dealer. Had to work on a turbo 280Z with drivability problems. I went
for a test drive and punched the throttle. It stuck at the floor. This was in
Edmonton in the winter with snowy icy roads. Solution, fill drawers and shut
the key off. Note not far enough to lock the steering!! Pulled the carpet
floor mat away from the throttle pedal. My 2009 Mazda 3 has a hook for the
mats to prevent this from happening. Another reason Mazdas are so well
accepted in the market place.

Dale Davies