Happened yesterday. Below is text of two messages I sent to NHTSA on
their complaint form. Notified AUDI US also, but no reply . I always
thought these claims were BS and from old drivers who accidentally
depressed the accelerator pedal when they thought they were pressing
the brake. It is scary, it is real and it needs to be looked into by
Audi. I skydive and I have had two main chute malfunctions that
required cutaways. I have experience in handling emergencies and not
panicking. I was NOT pressing on the gas pedal. I didnt want to shut
off the engine with the key until I was stopped as I feared losing
I looked on the NHSTA website and there have been a couple of other
complaints besides mine that were nearly identical. One guy assumed
like I did that it was a cruise control issue, but it isn't. He is
probably still driving thinking the problem has been fixed. The second
incident happened with the cruise fuse pulled.
Anyone have any ideas? The only clue was brake pedal effort seemed to
increase right before it happened, as if vacuum boost had been lost or
decreased. All ideas appreciated.
RUNAWAY THROTTLE. UNCOMMANDED ENGAGEMENT OF CRUISE CONTROL? WOULD NOT
RESPOND TO BRAKE OR SHUTTING CRUISE CONTROL OFF ON STEERING COLUMN
STALK SWITCH. VERY DANGEROUS!!! ALMOST CAUSED A CRASH, VERY
INEFFECTIVE BRAKING WITH ENGINE TRYING TO KEEP CAR GOING AT ABOUT 55
MPH, BUT I MANAGED TO PULL OVER AND SHUT CAR OFF. I PULLED THE CRUISE
CONTROL FUSE AND PROBLEM HAS NOT REAPPEARED.
DANGEROUS UNCOMMANDED ACCELERATION. I SUBMITTED A COMPLAINT EARLIER
TODAY THAT SAID I THOUGHT IT WAS A CRUISE CONTROL PROBLEM BUT IT ISNT.
IT HAPPENED AGAIN TODAY WITH THE CC FUSE PULLED!!! IT WAS PRECEDED BY
A FUNNY FEELING IN THE BRAKES, LIKE NOT ENOUGH VACUUM BOOST, THEN
RADICAL ENGINE ACCELERATION EVEN WITH MY FOOT OFF THE GAS PEDAL. I PUT
THE CAR IN NEUTRAL, THE TACH REDLINED AND THEN I SHUT OFF THE
IGNITION. STARTED IT AND IT DID IT AGAIN. I AM AN ENGINEER AND NEVER
BELIEVED THE STORIES ABOUT AUDIS AND UNINTENDED ACCELERATION... BUT
NOW I KNOW IT CAN HAPPEN AND IT IS SUPER DANGEROUS!!!!
You have the 2.8L V6 engine right Mark?
No examination after the incident? hmmm
I have seen you post before boeing377 so I do believe you. I just have not
personally seen something like this that could not be explained.
I would look at the throttle body, especially the throttle plates and their
I have seen the throttle plates get stuck due to corrosion and lack of
lubrication. I have cleaned and lubed many throttle bodies that were
operating stiffly/slowly on the AUDIs and VWs.
I have also seen floor mats that jam the accelerator pedal down. 8^o
Had a 1985 Audi 5000S for 20 years and NEVER experienced that problem
I also seem to remember that the problem showed up just after starting the
engine and AUDI could not replicate this issue.
Still they put on a AT Selector-Shift/Brake Switch Interlock on the cars.
Was AUDI the first to do this?
V 6 right. I normally would have torn into things trying to find a
fault, but I want Audi US techs to look at it undisturbed, that is if
Audi US ever responds to my emails. There was no floor mat issue and
it wasn't a sticking throttle as you might expect from a dirty
throttle plate, it rapidly and radically accelerated. In the second
incident I was in 5 mph city traffic and it took off. When I put it in
neutral it was up against the rev limiter, close to 5500 rpm with both
feet up and off the pedals. In the hands of a panicked old driver this
fault can and will kill people. Somehow there may be a clue in the
reduced brake boost prior to the uncommanded acceleration incident.
Can anyone see a way that reduced or falling brake boost vacuum could
cause or be related to this?
Then I wonder where the engine got its air supply from.
It must have thought it was on the runway taking off to fly! ;-)
I think on your engine you have a stabilizer valve that allows more air
inside of the engine controlled by the ECM. But I am not sure of the
controls on your engine except that it should have something to allow air
inside without accelerator intervention. Sometimes my '91 Passat will have
a very high idle and I need to cycle the ign off and back on. I think I
need to replace my ECM since I have checked everything else.
Glad you think on your seat! ;-)
Please post what is found.......I am curious!
Put your foot on the brake pedal. Have someone that knows where the
brake pedal is show you.
In *neutral*, rev the engine to 5000 rpms.
Now, drop the gear shift lever into drive.
I gots me a hundred bucks that says you won't move a foot.
road conitions. Your first instinct with a runaway throttle is to hit
the brakes and that is what I did first. It did stop the car with a
lot of effort. I then shifted to neutral, but got redline RPM. On the
first incident (uphill on a winding highway) I thought about shifting
to neutral while underway on the road but it might have left me
stranded on a blind curve since you cant shift back into drive easily
when an engine is redlining. I managed to use brakes to slow down and
pull over on a turnout.
By the way, Audi US is interested. They are paying to have it
inspected at a dealer. They have assured me that there has not been
one single case where unintended acceleration was proven. I told them
this isn't a "case". I am not suing anyone. It is a safety issue. Look
at the NHTSA complaint records online. There are two nearly identical
incidents reported for 92 Audi 100S. I think what distinguishes these
incidents from most of the ones widely reported many years ago with
Audi 5000s is that they (the reported Audi 100 cases including mine)
occurred underway, not during parking or startup.
See this handwritten letter, below the stock reply:
That is plain horse pucky. I had a 67 GTO with a stuck throttle (gas
pedal to the floor) and I applied the brakes and the car eventially
slowed to a safe speed where I could turn off the ignition and coast
to the break down lane. AND, those were drum brakes, not nearly as
good as any Audi's disc brakes.
You probably didnt read the part where it seemed like brake boost
vacuum was lost or reduced before it accelerated. That does increase
pedal effort needed. I am NOT claiming that brakes failed to stop the
car, they DID stop it. I think the vacuum loss or decrease is somehow
related to the uncommanded rapid accel. I AGREE with you that the Audi
brakes can and do eventually stop the car even with a redlined motor.
All it takes is a strong and continuous application.
In the old Audi 5000 cases that got all the news the vast majority of
the cases were as follows (from a news article):
"The Audi story is by now, dismally familiar. "Sudden acceleration"
accidents occurred when the transmission was shifted out of "park."
The driver always insisted he was standing on the brake, but after the
crash the brakes always worked perfectly. A disproportionate number of
accidents involved drivers new to the vehicle. When an idiotproof
shift was installed so that a driver could not shift out of park if
his foot was on the accelerator, reports of sudden acceleration
My experience and the experience of several other 92 100S owners
reported on the NHSTA site was not like this. It was uncommanded
sudden acceleration while underway. I always thought the Audi 5000
claims were driver error, but believe me , my experience and the
experience of several other owners as reported to NHSTA is really
different and far less likely to involve a driver jamming hard on the
gas pedal thinking it is the brake pedal. No shifting from park to D.
I was a huge skeptic so I know where you are coming from. This is a
real problem and not lawyer driven or driver error. I am not claiming
that the brakes failed to stop the car.
The cruise control system in your vehicle is completely separate from
any sources of engine vacuum and is controlled by a separate control
unit. The entire system is completely isolated from any other and
only uses inputs from other systems such as speed, etc.
All quite irrelevant since you have effectively removed the cruise
control system from the scenario by completely disabling it.
Leaving very little to possibly suspect. There is no other mechanical
control of throttle.
The components of the throttle body system are: the throttle body, a
potentiometer that senses throttle position and movement, the idle
stabilizer valve which meters air in order to keep a steady idle, an
EGR valve for emmissions control, and a temperature sensor. None of
the latter items mechanically manipulates the throttle body.
Without mechanical actuation of the throttle body and in order to
achieve the power output you describe, the engine will require
accurately metered air and fuel. I have no idea if the ISV or EGR,
either together or separately, could introduce a volume of air
equivalent to a fully opened throttle plate.
Nevertheless, air and fuel and accurate management of both must be
present to achieve anything remotely resembling full engine power.
Do you recall noticing the position of the throttle pedal? Was it on
What was the nature of your most recent throttle application?
The engine vacuum system on this model seems rather tortuous. There
is a "damper", the function of which I have no idea, a solenoid valve
of some sort, a "vacuum unit for intake manifold" which I believe is
merely an tap into engine vacuum, and some check valves here and
there. Then there's an entire subsystem built around a "suction
pump" (p/n 078 133 753) which also taps into the intake manifold. By
it's name it does not seem to be something that would introduce air
into the system, but in your case, something is clearly malfunctioning
so who's to say.
Finally, have you run the diagnostic output from the ECU to see if
there are any error codes stored? This may give you some add'l
I hope some of the above helps get closer to the cause. Give the age
of the vehicle, I'm very doubtful Audi or the NHTSA will do anything
Thanks for your thoughtful reply. Pedal was not on the floor when
uncommanded acceleration occurred, I recall tapping it on the first
incident thinking it might be hung up and found that it had a normal
amount of travel remaining.
On the first incident I had steady throttle, going uphill at 55 mph
with cc on but not engaged. On second incident I was in 5 mph bumper
to bumper traffic so I wasn't doing any significant throttle
excursions. I drive very smoothly and slowly in traffic, not jerky.
No floor mat issues. Accelerator pedal was unobstructed. When I
restarted the car in neutral, it went wide open, near redline, limited
only by the rev limiter (5500 RPM?). On the next restart idle was
normal. There is some link to a vacuum issue, I am pretty sure. Right
before the second incident the brakes took extra effort as if vacuum
boost was decreased or gone.
Have not run diagnostics. I am sure dealer will. I don't recall any
panel lights illuminating.
I hope NHTSA and Audi will take it seriously. An old defective car can
kill someone as easily as a new one. Audi seemed paranoid that I was
trying to get a legal case going, but I am not at all interested in
suing. I just want to keep someone from getting killed.
I was the biggest skeptic in the world about uncommanded acceleration
until it happened to me twice in one day. I am lucky that the second
incident happened with the cruise control fuse pulled. Otherwise I
would have incorrectly assumed that with the fuse pulled it could
never happen again and been driving blissfully unaware of the lurking
What puzzles me greatly is how the problem is intermittent.
On Jun 19, 10:30 am, email@example.com wrote:
First, I found a possible culprit. The neck on a 3 port plastic valve
in the vacuum line that runs on the top of the engine, driver side,
and feeds the brake booster was broken on the suction side (the side
that leads to the intake). The hose was sucked against the broken part
of valve when the engine was running so the vacuum loss was not
complete. What was disturbing is that the neck, which should have
remained firmly fit in the hose end, was missing and nowhere to be
found. Could this have disintegrated into small particles and have
been sucked into the throttle body? Could a foreign object here cause
increasing (not just stuck) fuel delivery? I don't know, but it is a
Audi America's response was waaaay beyond disappointing. They sent me
to a dealer who wrote up a $2000 repair estimate including $750 for a
new throttle pedal assembly, new floor mats, hundreds for
unspecified "decarboning" and did nothing to find the root cause.
Although this was CLEARLY an uncommanded acceleration issue, NOT A
STUCK throttle, they treated it as a stuck throttle issue and would
not even open up the cover to the throttle body on their dime. I
called Audi America HQ and spoke to Michael Harris. I told him I was
not making a legal case, not seeking money, just trying to prevent
fatalities. I told him that Audi could not possibly find the root
cause if they replaced every bad part before finding what caused the
problem. He was polite but wouldn't change anything. Oh well, I tried.
Who knows how many other 92 100S owners have had this happen. Three
have reported identical incidents to NSHTA, but I will bet there have
been others who didn't even know how to file a report. If this happens
to an old or non alert driver it cold result in multiple fatalities. I
am going to replace the broken valve, replace the old vacuum hoses in
that same line and see what happens. I am almost sure that the valve
lies at the heart of the matter since it causes partial/intermittent
loss of brake boost and that immediately preceded the acceleration.
The plastic was very brittle and the neck particles probably did get
get sucked towards the intake/throttle body, perhaps even entered it.
I don't know enough about the Audi fuel injection system to know if a
foreign object in this area could cause an increase in fuel delivery.
Does anyone else know?
1. Get a job and stop trying to make money off of Audi.
2. If you must drive, learn where the brake pedal is.
3. Please do not have children.
(who has been driving Audis for 25 years and knows there ain't no
sudden acceleration problem. There is not an engine made that can
overcome the brakes *IF they are applied)
First, there are several ways for an engine to uncontrollably
accelerate. Check recall listing web sites.
Brake booster blow-out or malfunction
Electronic throttle malfunction
Cruise control failure
Intake gasket blow-out
Broken throttle return spring
Throttle cable seizes
Second, the brakes in many cars can only hold back a full throttle
engine for a few seconds before overheating. Any teen who's thrashed
his car can tell you that.
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