Sudden Unintended Acceleration

[GMV22]

Anybody had an experience with their car accelerating suddenly and unintentionally? My car surged forward without me touching the accelerator, and I was wondering what the problem could be.

[michaelsn]

What year is your LS and how many miles do you have on it? The experts in this forum would probably need that in order to help you out.

:)

[mejojo]

Also, how far and how fast was the surge? 1/2 second taking you 5 feet? Kept going until you hit the brakes?

Joe

[basher_boy]

There was a post a while back about unintentional surging of LS400 cars a while back. My car does this. It happens to me mostly when I try to brake at low speed at a stop light or sign. It tends to last 2-3 seconds, and happens more often in the summer, while I am in stop and go traffic. Scary :o

[mobilyte]

message deleted

[basher_boy]

http://us.lexusownersclub.com/forums/index...T&f=4&t=922&hl=

here is the old post

[VMF]

does RPMs go higher when it happens? might be a problem with transmission. tranny switches into the lower gear but the torque converter not releasing

[GMV22]

Also, how far and how fast was the surge? 1/2 second taking you 5 feet? Kept going until you hit the brakes?

Joe

It's a 2001 LS 430, which took off like a rocket, speeding out of control immediately after I let up on the brake after putting the car in drive. The brakes didn't work either, and I ended up in a ditch. Someone could have been killed.

[90LS400Lexus]

Also, how far and how fast was the surge? 1/2 second taking you 5 feet? Kept going until you hit the brakes?

Joe

It's a 2001 LS 430, which took off like a rocket, speeding out of control immediately after I let up on the brake after putting the car in drive. The brakes didn't work either, and I ended up in a ditch. Someone could have been killed.

This sounds like a severe, life threatening issue. Is the car still under warranty?

I agree with MIG. This sounds like a problem that the 1980s Audi's had. It was dangerous problem with those cars.

[fiveofakind]

This problem needs to brought to Lexus's attention.

Let us know what you find out. If it happens again, just throw it into neutral & apply brakes.

Geez, never have heard of this problem before with any Lexus....

Jeff

[SRK]

For what it is worth, the Audi problem was finally determined to be pedal mis-application, which was more prominent in Audi vehicles due to the locations of the brake and gas pedals. In all cases, the brakes were found to be in serviceable condition post accident, and the mechanism by which the throttle was to have opened by itself was never explained mechanically. The installation of the shift interlock on the transmission reduced the accident rate to nearly zero.

Left foot braking was the root cause, and statistics showed that "unintended acceleration" was not limited to Audis alone, only that their rate of occcurence was leading the industry.

Two years ago I watched a woman drive her Taurus through a store front from about twenty feet away. She hit the gas, not the brake, when startled as the trans went into drive. I got her out of the car, and then checked the store - fortunately the person who would have been crushed at her desk was at lunch. No question that she hit the gas rather than the brake. The car was idling quietly afterwards. Brakes were fine.

The only method the Lexus could accelerate is by the Idle Air Control Valve, and its limited opening could not produce much power. Still, it needs investigating.

Most cars have brakes which are between four and five times more powerful than the engine, so stopping, even with a wide open throttle, is still possible.

I'm not trying to stir anything up here, but in an automatic car, left foot braking is a bad habit.

Of course, you can always hit the kill switch and "turn off the fire".

[CanadaCraig]

Hi SRK!! :)

Oh oh...

Trouble and toil - bubble and boil.....

You DID 'stir something up'!! lol

You said, "I'm not trying to stir anything up here, but in an automatic car, left foot braking is a bad habit."

I completely disagree. I believe that it's far LESS likely for a person who left-foot-brakes [an automatic - of course] to mistakenly THINK that they are 'braking' [when they are not] than a person who right-foot-brakes. [if that makes sense] It's just one of the many reasons I have always left-foot-braked. I think it's the safest way to drive.

[ok - I'm ready!!]

As for the Lexus suddenly surging forward - couldn't it just be the A/C kicking in? I know when MY A/C kicks in [when I'm at a light] I have to suddenly apply more pressure on the brake pedal to keep from moving forward.

Craig!! :)

[VMF]

Craig i have to do that too when i turn the ac on but its not enuff to be an emergency situation plus brakes still work

[doiturself]

I think it's the computer problem. The circuit board of the computer must have some damage component that causes your car not to work right.

[SKperformance]

To fly across anything and hit something is driver error.

If lexus found it was the car do you think they would let you drive it still??

People this isn;t GM or Ford ,they don't give one !Removed! about the customers once they get your money. My local paper sufficed to say shows peoples car gripes every saturday and it is always gm and ford and chrysler who either don;t respond or say too bad.

I will never own a domestic again pure crap. There is never a toyota or honda complaint, as tehy always look after the vehicle they made .Not abandoning it after the infancy or warranty is up.

Don't buy into this rumour that the car is the problem ,It is driver error and usually is.

The problem with the rpm rev's i would also say is the tranny downshifting.

If it is a newer car with brake force reduction ,then it might be itsway of getting ready to counter an evasive manouver

[jmblimo]

I think that it was proven that the problem wasn't the Audi 5000 but the stupid drivers not braking when they put the cars into gear. You know a fuel injection car usually starts with a little higher idle and you can imagine what will happen if you put the car into drive without pressing the brake. That's the problem. The folks were killing their kids and blaming the car.

[SRK]

The problem with left foot braking is that when we all learned to drive, we probably learned to brake with the right foot. So the ingrained psychological response to a "startling" event, like the car moving off inadvertently, is to stab the pedal with the right foot. If the right foot is over the gas, and the left over the brake, the result is obvious.

Research into this confirms that standard transmission cars do not experience unintended acceleration. Only automatics. This means that the "foot habits" of those driving automatics are different.

When one considers the options that are available to stopping a car which is TRULY running away in an unintended fashion, like switching off the ignition or shifting to neutral, that are NOT used by people in these situations, we have the evidence needed to indicate that in an emergency people react in ingrained ways, without thinking. If you teach your brain to leave your right foot over the gas pedal, after the right foot was trained to stomp the brake in a "startle" moment, you are asking for trouble.

The worst incident I listened to was a woman owner of an Audi 5000 who claimed that she sped down a California highway for over twenty miles (and about ten minutes) with the car running away in an uncontrollable state. Did she think to switch off the engine? Shift to neutral? Or even put her foot on the brake pedal? No. She went into dinosaur brain and stayed there. Her car was inspected and found to be in perfect working order, brakes included. And the Audi 5000, even in turbo form, had an enemic engine that could be easily overpowered by its braking system. I know, my father in law had an '88 turbo 5000 and I checked that fact (without telling him) as the "unintended acceleration" stories became newsworthy.

Cars do accelerate a bit faster than expected every now and then. As jmblimo stated, the start-up idle flare, designed into every fuel injected car with an IAC valve to limit starting emissions, can produce a faster creep speed in gear. And that, among other things, can startle a driver.

[basher_boy]

The problem for me is when in NYC type traffic I often don't have the luxurary of leaving myself any buffer in my driving style. When this does happen it takes an extra foot or two to stop, and that has on many occasions made for a panic. I only hit one guy, in a Merc, and thankfully he didn't care.

I had just assumed it was brake/gas interference (i.e. I mistakenly clip the gas pedal when I am on the brake). Problem is I am not the only person to have this problem in my car. Everyone that drives it for any time comes back and says to me "I almost rearended some one." It may just be the way the pedals are situated, and not a mechano/electrical/vaccuum type problem, but I have never been able to recreate the problem in a controled environment so that I can really pay attetion to it. It always happens during aggressive stop and go traffic type driving where a one or two foot mistake means a fender-bender, I have never had it happen when I am driving "nicely."

When it does happen it is over in the time it takes me to make sure my foot is repositioned well over the brake pedal, so who knows--is it driver error or a problem with the car--I will probably never be able to prove it.

[CanadaCraig]

I agree with what you said SRK. And just so you know - I certainly would NOT suggest that someone who right-foot brakes SWITCH to left-foot braking. I'm just one of the few [i suppose?] that was taught TO left-foot brake. I think it's the safest 'way'. In fact - I've never really understood the logic behind right-foot braking and/or why anyone would think that THAT is the best way. Whenever I'm going through a busy intersection - my LEFT foot hovers over the brake. The few milliseconds faster that I could begin braking [if need be] could be the difference between life and death. [for me OR for someone else]

Craig!! :)

[SRK]

What you describe Craig is called "covering the brake", but it is best done with the right foot, as the car coasts through the intersection. It is a very big habit of professional drivers, who drive, as I once did, large vehicles whose brake reaction times are longer due to air brakes, which have a lag period. There is also enough variation in modern cars between the placement and relative heights of the gas and brake pedal to cause problems while one adjusts to another car. That's what NHTSA found in the Audi case, and a few others.

[CanadaCraig]

That's interesting - SRK. And it makes sense - with vehicles that have air brakes. But it doesn't make sense [to me - at least!!] with ordinary vehicles. In an intersection - one never knows IF braking OR accelerating is going to make the difference between getting into OR avoiding an accident. By using both feet - I'm ready for anything!!

Craig!! :)

[SKperformance]

:o It is all a matter of perspective , if you where taught using both feet then you would feel it is better and it seems logial to think it is faster.

BUT

It is slower to use both feet !

Test yourself hold one hand( if you are right handed use your right , if left handed do the same ) against a desk and your other 6 inches above the desk.

Now pull up the one against the desk and push down the one in the air as fast as you can.

After doing this a few times you will get better but in an emergency reaction you will only have the speed of the first time you tried it. There are not retests.

Your brain is trying to counter one movement while applying another. You will either have one foot still on the gas while the brakes as being applied and reduce you breaking .

To do this properly in a car you need one foot ont 2. If for any reason you are in doubt of going faster then use the "hover " which is remove the right foot from the gas and hovr over the brake.

Which is what you should do through all intersections anyway.

[CanadaCraig]

Hi skperformance!! :)

I would agree with you IF people were 'left-footed' or 'right-footed' as they are left or right-handed. But they are not. When you go for a walk - is your left or right foot always trying to catch up? When you jump up and down - do you look like the Leaning Tower of Pisa? Probably not.

As for always hovering your foot over the brake while going through an intersection - I agree. I just think that 'foot' should be your LEFT foot and not your right. Like I said earlier - braking is NOT always the best way to avoid an accident. Sometimes stomping on the GAS pedal [and NOT the brake] will be what makes the difference between life and death.

IMHO

Craig!! :)

[LexusPete]

GMV,

I got some advise for you. You don't need a mechanic. You need an Excorsist :)

[SRK]

So Craig, when you drive the NSX, assuming it is a manual trans, do you cover the brake with your left foot?

In all my years of driving everthing from buses to semis and trucks of all sorts, I have never encountered a situation where accelerating got me out of trouble.

If you want to see if you have a dominant foot, run the hurdles. I am not a jock, but those that are tell me that you will figure it out very quickly running the 100 meter hurdles the first time.