what's wrong with this picture?

Dan Cordon cord4530 at uidaho.edu
Sun Mar 21 13:46:51 EST 2004


Kent Wrote:
> You've just plowed into a crowd of innocent bystander.
> What are you going to say, "I must have had my foot
> on the gas." or "The car wouldn't stop."? If you have
> no spine or ethics, you choose the latter.

I can't agree more. This is why every driver is forced to carry 
insurance. We make mistakes. The best of us have certainly made mistakes 
while driving a car, even if nothing was harmed.

What amazes me is how blatantly ignorant the general public is about 
cars. Here's how the facts look to me:
1) The recall (which had taken place already) was only for a sticky 
accelerator pedal. This means it may stick at full throttle *after* you 
have applied full throttle. Not that it may spontaneously give full 
throttle itself and then *stick* there.
2) As noted by many, the brakes on virtually any car will stop the 
vehicle even when full throttle is depressed. Many exceptions to this 
exist, but are likely in the form of highly modified cars ie: 30's hot 
rods with original brakes and supercharged V8's :o)
3) Any systems on the car that has potential for activating full 
throttle has many safeguards that must fail simultaneously. For 
instance, most cruise control systems don't work under 20 mph. Most 
ECU's are mapped such that the engine won't run past XXXX rpm while the 
throttle signal is closed.....etc.
4) If the engine is MAF based, then all the uncontrollable power was the 
result of metered air that has magically bypassed the closed throttle, 
then re-entered the intake again before being mixed with the correct 
amount of fuel. If it's MAP based, the engine will quickly die if large 
changes in manifold pressure occur w/o the throttle position sensor 
changing accordingly.

So, if I were a professional investigator I would logically conclude 
that something in the engine bay broke loose, forcing the throttle open. 
This was probably a part of the brake linkage, which explains why the 
brakes didn't help. However, the impacts from hitting several innocent 
bystanders *must* have dislodged the brake linkage from the throttle and 
popped the rogue linkage back in to place as to make the brakes function 
perfectly normal again after the incident.

Yes, I must conclude that, because the thought of human error - like 
'accidentally pushing on the gas when intending to hit the brakes' - is 
far less likely than the simultaneous failure of several vehicle systems.

<tongue in cheek of course>

I guess it's the fact that the driver isn't being looked in to at all 
that really troubles me. Perhaps the investigators will next seek to 
imprison the 'evil spirit' that temporarily takes control over innocent 
people, making them perform acts that people would never do 
intentionally (or accidentally).

Our judicial system is strange though. "Innocent until proven guilty." 
While this seems to be the case for the driver, Chrylser is put in the 
position of "Guilty until proven innocent." They're paying an 
engineer(s) to access what happened, and will probably pay several 
lawyers to defend the case in court. All because some guy hit the wrong 
pedal. Luckily for us, these charged will simply be distributed among 
all future Daimler Chrysler customers.

I've said too much-

-- 
Dan Cordon
Mechanical Engineer - Engine Research Facility
University of Idaho



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