Paul Stenquist wrote:
We already have too many OT threads, and I hesitate to extend this, but
I would like to offer a bit of information. Surges -- what feels like
the sudden application of power while driving -- are usually the result
of the opposite condition. That is, a temporary loss of power due to
the engine going very lean or losing spark. If the driver is
maintaining a steady speed when the engine loses power, he
instinctively pushes a bit more on the accelerator. Because the loss of
power is smooth and quite, it is notice only in the way a driver might
respond to a slight incline: a bit more throttle. When the lean
condition disappears or the spark returns, the throttle is now in a
different position, and the reapplication of power feels like a rather
aggressive surge. It's common and real. The lean condition can be
caused by air in the fuel pump, dirty injectors, water in the fuel and
myriad other conditions. Spark failures can be the result of any
number of electrical faults.
On the other hand, the sudden acceleration problems that were
attributed to Audi some years ago were pure fiction. As Ken noted, the
throttle of a car that is sitting at idle cannot open on its own.
Extensive government sponsored research showed that all of these
incidents were the result of operator error: stepping on the
accelerator rather than the brake. While incidents were recorded with
almost all makes, they were most common with Audi, due apparently to
the close placement of accelerator and brake pedals and perhaps to a
large number of numb owners.
Paul
But, in fact, a few of the occurences that happened to me were when I
was stationary, with the handbrake on, in neutral, no feet on the
pedals. The engine revs rose without input from me. It was those
incidents that caused me to realise that the condition was not operator
error, as I had assumed up to then. It was the engine management system
deciding that the cat needed to be warmed up and doing so. Not the same
phenomenon as Kenneth was talking about (my mistake there) but
definitely the vehicle deciding to do what it thought was good for it
without any input from me.
It appears that modern, multiple lambda sensor machines are less prone
to the problem but it may still occur as a fault rather than a design
parameter.
m
On Feb 18, 2006, at 11:43 AM, mike wilson wrote:
Kenneth Waller wrote:
There were definite power surges without any throttle application
by me,
Ok, so where did the extra air & spark come from to ignite with the
extra fuel?
The surges were not severe but they did produce secondary
adrenaline surges when they occurred in close traffic
Ok, were they controllable by application of the brake?
The cause was given to me by the Automobile Association patrolmen
who attended
I guess they should have told that to the several governments that
investigated the issue.
Kenneth Waller
Ken, I don't want to get into a big debate about this. I know what
happened to me but it appears you are talking about something
different - much more violent than what I experienced. The
explanation I received made perfect sense to me. If it doesn't for
you, there is not much I can do about it. WRT the phenomenon you are
talking about, there was an incident in this town with a runaway bus
that was attributed to the problem, at least by the driver. There
have been numerous reports of the same problem with other examples of
the same bus. Here's one:
http://www.crawleytoday.co.uk/ViewArticle2.aspx?
SectionID=496&ArticleID=730454
mike
----- Original Message ----- From: "mike wilson"
<[EMAIL PROTECTED]>
To: <pentax-discuss@pdml.net>
Sent: Friday, February 17, 2006 4:59 PM
Subject: Re: OT: HCB with a Minolta CLE
Kenneth Waller wrote:
We're not talking about the same phenomenon. You use the term
surge - generally interpreted as short duration & slight to
moderate acceleration.
The typical sudden accel event that I've been involved with is a
longer duration event that appears to duplicate a wide open
throttle event & most times is purported to not be controllable
with the brake application.
With the fuel injection systems that I'm familiar with the
throttle body acts as an air valve, which is controlled by your
right foot. Fuel is controlled by the engine processor & is added
to the combustion process based on the position of the throttle.
Air, fuel & spark must be combined at specific ratios for correct
combustion to be obtained. Too much fuel & the engine runs rich &
doesn't produce optimum power. Too little fuel & the engine runs
lean & doesn't produce optimum power.
Additionally, what you're talking about is taking place outside
the combustion chamber. I don't see how that has anything to do
with the production of engine power.
Kenneth Waller
The fuel has to go through the engine to get to the cat, so will
affect power output. The stoichimetric ratio is an ideal, probably
never achieved in practice throughout the combustion chamber, so
extra fuel could produce more power. There were definite power
surges without any throttle application by me, in situations where
I could believe the cat was not at proper temperature. The cause
was given to me by the Automobile Association patrolmen who
attended. They had, at that point in the early 1990s, had numerous
calls about the problem.
The surges were not severe but they did produce secondary
adrenaline surges when they occured in close traffic.
m
----- Original Message ----- From: "mike wilson"
<[EMAIL PROTECTED]>
Subject: Re: Re: OT: HCB with a Minolta CLE
From: "Kenneth Waller" <[EMAIL PROTECTED]>
Most major auto manufacturers have been sued with sudden accel
as the
allegation.
I've experienced this with a couple of vehicles. As far as I
could ascertain, it was a function of the fuel delivery system to
deliver excess fuel if the catalytic converter temperature fell
below a threshhold. The unburnt fuel reacted in the cat and
raised the temperature - a byproduct was a small surge in
acceleration, rather like the one you feel when the injectors
kick back in on the overrun to generate idle speed but much more
prolonged and at any throttle opening.
mike
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