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Putting the stuck gas pedal vs. brakes to the test

M

MikeMike

Lifer
http://blogs.consumerreports.o...egies-to-the-test.html

October 14, 2009
Jake Fisher, Consumer Reports Cars Blog

Putting stuck floor mat survival strategies to the test

Recent reports of stuck accelerator pedals causing crashes and Toyota?s enormous recall has caused many to question whether or not a vehicle?s brakes are powerful enough to overpower the engine to stop a vehicle, and what you should do if you are ever in that situation. Most experts agree that a typical production car engine won?t overpower the car?s brakes from a stop. But what happens at speed is another question. Since we just happen to have a test track and a few dozen test cars at our disposal, our automotive engineers decided to play MythBusters and put it to a test.

Our first two subjects were the Mercedes-Benz E350 and Volkswagen Jetta Wagon, German cars with so-called ?smart-throttle? technology. Both will electronically ignore the throttle input if the brake pedal is depressed. With both, we accelerated to 60 mph and then hit the brakes with the throttle pedal still planted to simulate a condition where the floor mat might have stuck it in place. With both vehicles, we were able to safely slow to a stop despite the engine having been at wide-open throttle. After stopping, the engines idled even with the throttle pedal still floored.

Verdict: The Mercedes and Volkswagen Smart-Throttle technology works.

Next up, we tried our Toyota Venza and Chevrolet HHR. Since these lacked smart-throttles, we proceeded more cautiously. So we decided to start this test by flooring the cars to 20 mph (instead of 60) and then slamming on the brakes. While we stopped both cars, the transmissions downshifted hard, trying to fight us on the way down, and we needed to exert quite a bit of brake pedal effort to stop completely. We then drove a lap around our test course to cool the brakes and repeated the procedure. This time we accelerated to 60 mph before we slammed on the brakes. Again, the engines downshifted and fought us all the way down. But by the time we slowed down to about 10 mph, the brakes had faded so much that we weren?t able to come to a complete stop. If the driver had less strength or was traveling at higher speeds, they would not be able to slow down nearly as much.

Verdict: Most people will likely have a tough time stopping a car using the brakes with a stuck throttle without a smart throttle.

So what should you do if you are put in such a situation? The answer is simple: Put the car in neutral. In each one of the cars we tested, we were able to easily nudge the gear lever into neutral and stop the car quickly. All modern engines have rev limiters that prevent the engine from over revving and damaging the engine. You can safely shut off the engine after you come to a stop. However, we do not advise shutting off the engine while still driving. We tried this with our Toyota Venza?as Toyota suggests?by holding down the start/stop button for three seconds. While this also allowed us to stop, we lost power steering and had trouble maneuvering the vehicle due to the extremely heavy steering.
Click to expand...

enjoy
 
Had a weird DBW event once in my WRX, got off the highway, sitting at a red light for a couple minutes, light goes green got a little lazy with the clutch and almost stalled.

Pushed the clutch in, blip the throttle, revs shoot up to 4K and stay there for a good 3 seconds with my foot completely off the pedal.

Was about to kill it, when it miraculously went back to idle and I took off normally.

Certainly an unsettling event but manageable. If I had been at speed it would have been a lot more difficult to defuse, but how so many people in this situation simply "give up" and let their car barrel off into traffic or whatever is beyond me. You drive the car, the car doesn't drive you - even with a stuck gas pedal.
 
Wow, well that pretty much says it all. 60mph is a fraction of the kinetic energy that is happening at even 80mph, so there is a point of no return basically. With V6 motors pushing 200-300hp, that's gotta be a nightmare.

Solution is what pretty much everyone already said : go to neutral.
 
I was easily able to stop both cars I tested with only my left foot on the brake, from above 60mph, with the throttle held to the floor with my right foot.

I reported my tests here.

I tested a 2008 Jeep GC Limited 4X4 5.7L Hemi and a 1996 Lumina 3.1L V6.

The Jeep has the electronic throttle, the Lumina does not. Jeep has 4 wheel discs and is nearly new. The Lumina has drums on the back and it's original pads and shoes.

I had no trouble stopping both vehicles. I did multiple tests.

As an additional test, I also pumped the brakes on the Lumina 4 times before holding the brakes on on the 5th pump. I also did the brake pump test several times.

I still was able to stop the Lumina.

Certain tests obviously took longer, but there was never any doubt that the brakes were going to stop the vehicles.

At no time did it ever seem like the vehicles weren't going to stop. It was always obvious to me that they would stop, and they did.




 
My test reports:

2008 Jeep GC 4X4 Limited 5.7L Hemi with 4 wheel discs and 5800 miles on it. Full time 4wd.

It has all the gadgets including brake assist, electronic throttle, hill start assist, hill descent control, traction control, stability control, tip start, etc. It is a CAN bus vehicle.

Tip start is similar to push-button start.

I went over to a local highway to see if my Jeep would stop at full throttle and learned a few things. I warmed the brakes up with a few stops and a little bit of dragging.

Was going downhill on an on-ramp with no one anywhere near me.

Brought it up to 60 gradually and then floored it. Let it go for a bit and then braked firmly with my left foot only, holding the throttle down with my right foot.

Braking action was strong and the Jeep slowed dramatically. It got down to about 5 mph pretty quickly, engine still roaring, but otherwise undramatic.

At about that point, the electronic throttle lamp came on and the computer dropped the engine to idle.

So, barring a brake failure, I can stop my 5.7L hemi at full throttle from highway speeds with just my left foot on the brake.

Also, the Jeep's computers recognized the throttle/brake conflict pretty quickly and set the throttle at idle.
Click to expand...

1996 Lumina LS 3100 V6 front wheel drive 160HP Disc/Drum ~48,000 miles - poorly maintained with an occasional anti-lock light and occasional sticking drums. Original pads and shoes. Old tires that need replacing on the front. It was about 50 degrees out, so fairly cool.

First test was with stone cold brakes. Held the car at 60 and then floored it. Braked with left foot only, holding throttle down with right foot. Very obviously going to take a while to stop. Braking action weak but clearly effective and the car did stop. Much weaker braking than I expected and much weaker than my Jeep.

Second test shortly after the first to test with heated up brakes. Much stronger braking action this time, same result. Obviously going to take longer than normal but clearly effective. Stopped quite a bit quicker this time.

Third test was to see how good the brakes were now that they had two panic stops on them. This was done with the throttle at idle from 65mph. Braking action was strong and normal.

Did a 4th full throttle test after the brakes cooled a bit. Similar results. No problem stopping.

Went about my business for a while to let the car return to normal and then did 4 more tests on the way back. These tests were to see what effect pumping the pedal had.

Held the car at 60 for a bit, then floored the throttle. Pumped the brake pedal hard 4 times and on the 5th pump I held the brakes on. Pedal was hard and high but I still seemed to have power assist. Seemed to take longer but otherwise the results were similar. I still clearly had effective brakes and they still were clearly going to stop the car, and they did.

Basically same results for the next 3 tests. I did the same thing, pump 4 times and then hold on the 5th. The brakes seemed to get more effective with some heat in them, as I would expect.

I never lost the brakes and it was always obvious that I had effective, if weaker, braking.

There was never any question in my mind that the brakes would stop the car.

Again the Lumina returned to normal quickly and the brakes acted normally after the 4 tests.

There were no apparent ill effects on the car and no warning lights. The engine temp remained normal. The transmission shifting was normal at all times.
Click to expand...

Just did the promised light application of brake and throttle with my Jeep while moving. It did indeed recognize the conflict and try to save me. Throttle light came on and power was reduced.

At a stop, the computer allowed me to brake torque.

While moving, it intervened fairly quickly.
Click to expand...
 
This is why I always make a very big point to explain the use of Neutral to new drivers. I've only taught a few people to drive "from scratch" (my girlfriend's younger siblings, one of which just got her permit), but I've also taught the concept to a scary number of experienced drives, some that are twice my age.

Whenever I drive a car that has a potential for a sticking accelerator (pedal or otherwise), I always keep one hand on the shifter. Recently my girlfriend's car started accelerating randomly, against her will (without the pedal depressed). I've drilled it into her head that before she tries to emergency stop, the shifter goes to "N" first, just in case the problem starts up again at a critical moment.

What would these poor, unknowing people do if their brakes suddenly gave out? It's not unheard of for people (shit heads) to vandalize brake lines in parking lots. Ugh.
 
Originally posted by: Arkaign
Wow, well that pretty much says it all. 60mph is a fraction of the kinetic energy that is happening at even 80mph, so there is a point of no return basically. With V6 motors pushing 200-300hp, that's gotta be a nightmare.

Solution is what pretty much everyone already said : go to neutral.
Click to expand...
I don't see what's so hard about that. Put it in neutral, then cut it off and coast to a stop. Steering will be stiff, and so will the brakes, but they'll still work.

I remember years ago reading about how some state troopers tried to stop an old lady whose gas pedal stuck to the floor.....one tried getting his patrol car in front of hers and slowing it down....burned his brakes until they faded. Don't remember what eventually stopped her, but I don't think she wrecked.

But all she had to do was put it in neutral and let it blow, or shut it off and coast to a stop.
 
Originally posted by: LTC8K6
http://i3.photobucket.com/albu...917-1911M/IMG_1981.jpg

I finally know why the guy didn't shift into neutral.

Poor shifter layout and markings.

A lot of people would never find neutral if they had to in a hurry.
Click to expand...

Holy crap. Is this post for real?

YOU PUSH THE SHIFTER FORWARD. THAT'S IT. BAM. NEUTRAL. You don't need to move it around at all, you just push forward and it's there.

In my Accord (shift button rather than staggered gate), you don't even need to push the button to get neutral. There's no lockout or anything. You just push forward and it's there. How could they possibly make it any simpler other than installing lawnmower-style kill-switch handles that you have to hold the entire time you drive?
 
Originally posted by: Pacfanweb
Originally posted by: Arkaign
Wow, well that pretty much says it all. 60mph is a fraction of the kinetic energy that is happening at even 80mph, so there is a point of no return basically. With V6 motors pushing 200-300hp, that's gotta be a nightmare.

Solution is what pretty much everyone already said : go to neutral.
Click to expand...
I don't see what's so hard about that. Put it in neutral, then cut it off and coast to a stop. Steering will be stiff, and so will the brakes, but they'll still work.

I remember years ago reading about how some state troopers tried to stop an old lady whose gas pedal stuck to the floor.....one tried getting his patrol car in front of hers and slowing it down....burned his brakes until they faded. Don't remember what eventually stopped her, but I don't think she wrecked.

But all she had to do was put it in neutral and let it blow, or shut it off and coast to a stop.
Click to expand...

Remember the trooper was stopping two cars, probably both big and heavy, not just one. So it makes sense that his brakes might fade even if they could have stopped his own car with the throttle pinned.
 
Originally posted by: thomsbrain
Originally posted by: LTC8K6
http://i3.photobucket.com/albu...917-1911M/IMG_1981.jpg

I finally know why the guy didn't shift into neutral.

Poor shifter layout and markings.

A lot of people would never find neutral if they had to in a hurry.
Click to expand...

Holy crap. Is this post for real?

YOU PUSH THE SHIFTER FORWARD. THAT'S IT. BAM. NEUTRAL. You don't need to move it around at all, you just push forward and it's there.

In my Accord (shift button rather than staggered gate), you don't even need to push the button to get neutral. There's no lockout or anything. You just push forward and it's there. How could they possibly make it any simpler other than installing lawnmower-style kill-switch handles that you have to hold the entire time you drive?
Click to expand...

Did you even read the thread on rimfire central, where the picture was lifted from? The author states that moving the shifter to the neutral gate on the left at full throttle does not actually shift the transmission into neutral. The ECU for whatever reason locks out neutral under WOT. The only way to get into neutral is to move the shifter into the center gate and hold it in the forward position.

Intuitively you'd do exactly as you suggest, move the gear selector forward to the gate marked N on the left, at an idle I do believe this would work, even at low RPM it may work but at WOT apparently it doesn't, instead the driver has to find a position in the gear selector that is normally ignored and not obviously marked on the center console. In a moment of panic with 100 MPH quickly approaching it may not be so simple to find neutral the way the gear selector is marked combined with the fact that the ECU overrides the manual gear selection under certain conditions. I've never driven a vehicle when the throttle gets stuck wide open, sitting at my desk it's easy to say I'd shift into neutral and apply the brakes, but being drunk on adrenaline in a real world scenario I can't say I'd do much better than stuffing it into the guardrail.
 
Originally posted by: thomsbrain
Originally posted by: LTC8K6
http://i3.photobucket.com/albu...917-1911M/IMG_1981.jpg

I finally know why the guy didn't shift into neutral.

Poor shifter layout and markings.

A lot of people would never find neutral if they had to in a hurry.
Click to expand...

Holy crap. Is this post for real?

YOU PUSH THE SHIFTER FORWARD. THAT'S IT. BAM. NEUTRAL. You don't need to move it around at all, you just push forward and it's there.

In my Accord (shift button rather than staggered gate), you don't even need to push the button to get neutral. There's no lockout or anything. You just push forward and it's there. How could they possibly make it any simpler other than installing lawnmower-style kill-switch handles that you have to hold the entire time you drive?
Click to expand...

I see that you might not have found Neutral in the Lexus either if it was your first drive.

In the picture the shifter is in Neutral. Drive is straight back from Neutral.

A person unfamiliar with the car will almost certainly put the shifter all the way over to the left, in the "Shift it yourself" S gate, for Drive. Since they won't be shifting it themselves, they will never know that it isn't actually in Drive, but in Sport mode.

Looking at the shifter, and not realizing you aren't in Drive, it looks like you should push forward for Neutral. There's a green N right there. Well, that won't get you Neutral. A forward push only gets you an upshift. Neutral is right and up from Sport mode.

The right gate is R and N
The middle gate is N and D
The left gate is S

With a little practice, you'd get the hang of it. Without practice and in an emergency, I can easily see someone claiming it would not go into Neutral. I can easily see why the driver in question probably didn't realize where Neutral was.

The N and R labels should be moved over to the gates they are actually in, imo.

I'll bet a lot of folks are driving around in S instead of D.





 
Originally posted by: halik
Originally posted by: LTC8K6
http://i3.photobucket.com/albu...917-1911M/IMG_1981.jpg

I finally know why the guy didn't shift into neutral.

Poor shifter layout and markings.

A lot of people would never find neutral if they had to in a hurry.
Click to expand...

What are you talking about. Standard layout - push shifter up from D to N, pull shifter from N to D. It's the same thing, the only difference is notched shift pattern.
Click to expand...

Try to put yourself in the shoes of a person who just got the car and is unfamiliar with the shifter.

Don't you think they might put it in S and not realize it's not actually Drive?

Once they have made that error, it's logical to think that Neutral is forward.

What if he'd never driven a slapstick before and thought that the shifter was returning to drive and refusing to stay in Neutral?

It's an easy mistake, imo.

Of course, I don't really know how familiar the guy was with that Toyota pattern. For all I know, he had driven a car with one before, and there's still no explanation of why he didn't use Neutral.

My crudely relabeled shifter gates. 😀

http://www.mediafire.com/imgbn...d1fd8c17c79eee594g.jpg

 
Originally posted by: LTC8K6

Try to put yourself in the shoes of a person who just got the car and is unfamiliar with the shifter.

Don't you think they might put it in S and not realize it's not actually Drive?

Once they have made that error, it's logical to think that Neutral is forward.

What if he'd never driven a slapstick before and thought that the shifter was returning to drive and refusing to stay in Neutral?

It's an easy mistake, imo.

Of course, I don't really know how familiar the guy was with that Toyota pattern. For all I know, he had driven a car with one before, and there's still no explanation of why he didn't use Neutral.

My crudely relabeled shifter gates. 😀

http://www.mediafire.com/imgbn...d1fd8c17c79eee594g.jpg
Click to expand...

If neutral doesn't work, toss it in Reverse. Park. Turn off the ignition, hold the start button. It's common sense. If you got enough time to call 911, you've got enough time to problem solve a device you've used a million times before.

Besides the point, it says S-D on the shifter. That alone should give you the idea that there are 2 positions when the shifter goes across... plus it LIGHTS UP THE SELECTED POSITION.

It's that or you can have the idiot's solution of ziptied mats to the seat. Poetic justice IMO.
 
Come to think of it, the guy dropped his own car at the Lexus dealer for service, which suggests he should have been familiar with the shifter.

I wonder if he always drove around in S, blissfully unaware that he was not in D?
 
If you are driving in S you would know, because the display on the dash tells you that, and also it tells you what gear you are in. Also the gears would never shift if you are in S and that would be a problem.

Gear information is not displayed if you are in D.
 
Originally posted by: halik
Originally posted by: LTC8K6

Try to put yourself in the shoes of a person who just got the car and is unfamiliar with the shifter.

Don't you think they might put it in S and not realize it's not actually Drive?

Once they have made that error, it's logical to think that Neutral is forward.

What if he'd never driven a slapstick before and thought that the shifter was returning to drive and refusing to stay in Neutral?

It's an easy mistake, imo.

Of course, I don't really know how familiar the guy was with that Toyota pattern. For all I know, he had driven a car with one before, and there's still no explanation of why he didn't use Neutral.

My crudely relabeled shifter gates. 😀

http://www.mediafire.com/imgbn...d1fd8c17c79eee594g.jpg
Click to expand...

If neutral doesn't work, toss it in Reverse. Park. Turn off the ignition, hold the start button. It's common sense. If you got enough time to call 911, you've got enough time to problem solve a device you've used a million times before.

It's that or you can have the idiot's solution of ziptied mats to the seat.
Click to expand...

Well, a pax called 911, not the driver.

Maybe the black box will tell us something.

I guess there will always be questions about why the driver didn't do any number of things, even if we assume the tranny wouldn't go into Neutral.

Thinking about it, for me, not going into Neutral wouldn't make me panic. I'd just move on to the next attempted solution.
 
Originally posted by: BassBomb
If you are driving in S you would know, because the display on the dash tells you that, and also it tells you what gear you are in. Also the gears would never shift if you are in S and that would be a problem.

Gear information is not displayed if you are in D.
Click to expand...

If you just put the shifter in S and don't do anything, the trans won't shift? It will stay in first gear, you mean?

If so, that would seem to put the blame on the car again because it would eliminate any confusion on the part of the driver.

 
"The initial shift range in S mode is automatically set to 5 or 4 according to
vehicle speed."

I think that means it will shift by itself if you put it in S and don't do anything else.

It's essentially in Drive, but 6th gear won't be used.

At least, that's the way I read the 250/350 manual.
 
The way you made it sound was that people drive daily all the time not knowing they are in S which wouldn't work.

But yea if they shifted into S while they were driving it would do as you state
 
Originally posted by: LTC8K6
"The initial shift range in S mode is automatically set to 5 or 4 according to
vehicle speed."

I think that means it will shift by itself if you put it in S and don't do anything else.

It's essentially in Drive, but 6th gear won't be used.

At least, that's the way I read the 250/350 manual.
Click to expand...

The Camrys I've been renting have this same shift pattern and (I believe) the same 6-speed automatic (Hertz rents the Camry SE variants with the 6-speed rather than the 5-speed LE models).

The "S" mode allows a driver to select the highest gear used by the transmission, and while the transmission will no up-shift (it will let you bounce off the rev-limiter forever if you select 1st gear, don't tell Hertz that I tested this), however if you select 4th or 5th from a stop the transmission will still start out in 1st and shift up through the gears normally.

Holding the slap-shifter forward in "S" mode will select S-6 mode without needing to progress through the intermediate modes (e.g. if you're in S-2 and push the stick forward and hold it, the transmission will select S-6 rather than S-3 as it would if you just pushed it forward and immediately released it).

The "S" mode is mainly useful for downshifting on long hills or to prevent hunting (for some reason I've noticed that the transmission hunts between 3rd and 4th at a steady 25 mph so I'll use S-3 to lock out everything above 3rd and prevent hunting in towns). It also does slightly change the shift mapping to make the shifts a bit firmer and to respond with a downshift more readily when you give the car more throttle.

"S" mode also will not allow a manual downshift at certain speeds, even if the downshift would not cause the engine to operate at redline. For example, 2nd gear does not redline until about 40 mph, but if you try to downshift into S-2 at 30 mph, the transmission will not allow it.

It took some getting used to.

ZV
 
Originally posted by: Zenmervolt
Originally posted by: LTC8K6
"The initial shift range in S mode is automatically set to 5 or 4 according to
vehicle speed."

I think that means it will shift by itself if you put it in S and don't do anything else.

It's essentially in Drive, but 6th gear won't be used.

At least, that's the way I read the 250/350 manual.
Click to expand...

The Camrys I've been renting have this same shift pattern and (I believe) the same 6-speed automatic (Hertz rents the Camry SE variants with the 6-speed rather than the 5-speed LE models).

The "S" mode allows a driver to select the highest gear used by the transmission, and while the transmission will no up-shift (it will let you bounce off the rev-limiter forever if you select 1st gear, don't tell Hertz that I tested this), however if you select 4th or 5th from a stop the transmission will still start out in 1st and shift up through the gears normally.

Holding the slap-shifter forward in "S" mode will select S-6 mode without needing to progress through the intermediate modes (e.g. if you're in S-2 and push the stick forward and hold it, the transmission will select S-6 rather than S-3 as it would if you just pushed it forward and immediately released it).

The "S" mode is mainly useful for downshifting on long hills or to prevent hunting (for some reason I've noticed that the transmission hunts between 3rd and 4th at a steady 25 mph so I'll use S-3 to lock out everything above 3rd and prevent hunting in towns). It also does slightly change the shift mapping to make the shifts a bit firmer and to respond with a downshift more readily when you give the car more throttle.

"S" mode also will not allow a manual downshift at certain speeds, even if the downshift would not cause the engine to operate at redline. For example, 2nd gear does not redline until about 40 mph, but if you try to downshift into S-2 at 30 mph, the transmission will not allow it.

It took some getting used to.

ZV
Click to expand...

My car does the same thing - put it in tip mode and it will not upshift (will downshift however). The fact the S gate has up and down (+ / -) gates would make me thing it works the same way.
 
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