electronic throttle

well you might think you do, but in reality you don't.

but you still don't understand why it's like that apparently.

then you're not reading what i said or understanding the control principle.

only if you don't understand!

 

get some experience bob. some cars do use electric pumps for power
steering. toyota is one of them. not all models, but some.

 

Cite.

Toyota's electric steering does not use an electric motor to drive a
hydraulic pump. There are makes that use such a system, but Toyota isn't
among them, and certainly the Corolla does not use that system, which is the
model that is having steering problems.

 

bullshit. mr2. look up your own cites.

sure, i'll take the word of a guy that doesn't know what he's talking about!

 

3 inputs are an absolute necessity for true"fail-safe" systems. If 2
inputs dissagree, what do you know, other than that you have a
problem. With 3 inputs, if 2 agree and one dissagrees, you have a
pretty good idea which input is wrong.

 

yeah, i get that, but where are the three inputs? does any vehicle have
more than one pedal position sensor?

 

With car computers overriding the drivers inputs to correct an
unbalanced car that may involve applying power when the the driver is
using brake certainly implies complexity that if not exhaustively tested
with logic tables and safety checks on sensors could lead to unintended
outputs and maybe race conditions.

 

I think it all boils down to the fact that cars have become nearly as
complex as airplanes. Difference is that planes are "driven" by highly
trained operators and the aircraft itself is highly maintained. This
difference spells trouble at some point for consumers many of whom are
morons to boot.

We can thank the guv'ment for most of these "innovations.

Guv'ment mandates safe cars so they naturally become heavier.

Guv'ment mandates fuel efficient cars so they become gagetized with
sometimes costly results and compromises in safety.

Meanwhile the consumer becomes so dumbed down that they cannot react to
basic emergency conditions adequately. Hell, how many Toyotas have
malfunctioned in the whole scheme of things??? Not that many.

Oh well, that's why I drive twenty-five year old junkers with mechanical
throttle linkage...

JT

 

I think I understand it. Let's see...

Similar concept to a Quadrajet carburetor's secondary throttle plate?
In that example, the secondary's linkage is connected to the primary's,
and moves when you floor the gas pedal, but if the choke hasn't opened
all the way yet, then the secondary plates are locked, and not permitted to
open, to prevent the engine from bogging or even stalling when cold.

As above, with your cable/computer hybrid system, flooring the gas pedal will still
allow the spring-loaded linkage to move, but the throttle plate will only follow the
linkage and open *if* the computer thinks it's safe to do so. If the system sees
you're also pushing hard on the brake pedal, or the car is sliding sideways, or the
ABS system kicks in on a slippery road, or the magic eye scans the invisible bar
code on the speed limit sign and decides you're going too fast, it can override the
gas pedal's position and close the throttle, either partially or completely. All you'd
feel is a decrease in power, and more resistance at the gas pedal as the throttle
plate was pulled closed against the "follow-me" spring in the linkage.
Sounds a lot like the "Traction Control" systems already in use on some cars.

 

We have had three cars (one made in 1997, the second in 2002 and the third
in 2004) that sometimes used to open the throttle on the 'over run',
possibly to reduce emissions.

It was unnerving approaching junctions.

All three had mechanical throttle cables, but also motors built into the
throttle body to drive the throttle plate open.

Two were Fords, the other was a Daewoo with a Suzuki engine.

Best wishes

David



--- news://freenews.netfront.net/ - complaints: ---

 

You're a bit behind the times, our E34 Alpina B10 had an electronic
throttle, it was a 1989 car!

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In my Prius I am unaware of any 'kill' switches. There is just the
normal power on-off switch. It is a simple sp-st switch that acts
(through the computer) as an alternating switch.

 

The problem is that now lawyers, politicians and news media are driving (no
pun intended) solution. The way I see them talking, cars will wind up with
a fail-safe throttle that is more fail-safe than the controls of a jumbo
passenger jet.

 

I'm not sure about this but for sure... The causes you cite certainly
contributed in getting to where we're at!

Oh, don't forget that little incident when a B-777's engines went to
idle about a minute before touch down at Heathrow about a year ago.
Aircraft was totaled but there were no major injuries.

Cause has been assessed to software/computer glitch.

JT

 

I believe that was traced to icing in the fuel system. SOP now is to cycle
fuel after prolonged low temp at altitude.

 

One throttle position sensor of the simplest design (a simple
potentiometer) can provide 2 signals - one the inverse of the other.
The third input could be as simple as a closed throttle ot WOT sensor
switch.

If the Throttle position and the _throttle position switch dissagreed
about whether the throttle was open or closed (ie - the sensor was
open or shorted) the idle position switch would confirm if in fact the
throttle was at idle. (or the WOT could confirm if it was at WOT)

The idle position switch is the simplest because when you first start
the engine the computer could poll the position sensor, and if both
sides of the pot did not indicate closed throttle, the switch could be
asked for it's "vote".


That is your "3 inputs" in it's simplest form.

 

I think you'll find that commercial and private airliners go in the
exact opposite direction.

 

Chevrolet's not unique in that regard. The persistant occurance of cars
with paddle shifters whose operation have no co-relation to the actual
shifting of gears is more of 6the same.

At a glance it sounds to me like we're not actually hearing from people
who *know* what the problem is yet. Merely seems to be the background
noise of the press et all.

 

"tandem throttle" Where the computer cannot OPEN the throttle unless
the cable op throttle is also open, but the computer can close the
throttle any time it likes. The computer can also control the opening
of the throttle within the confines of the limit established by the
cable op throttle.

 

Virtually ALL port injected engines have an electrically operated
"idle speed control" or "air bypass" valve that bypasses air past the
throttle valve for several purposes. It is uded to raise (or maintain)
idle speed when AC is operated, headlights are turned on, or power
steering is used at idle, and it is used to prevent abrupt throttle
closure on decel for emission reasons.
Some older vehicles used an "idle up" solenoid for the same purpose,
while others had an "anti-diesel" solenoid to close the throttle
completely when the ignition was turned off. Other older vehicles used
a "dash pot" or vacuum idle control to do some of the same.

Vehicles with Drive By Wire, in large part, eliminate the ISC system -
which, by the way, is one of the more problem prone subsystems on most
fuel injected vehicles of the last 20 years or so.