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What to do if your car accelerates out of control

  1. Jan 27, 2010 #1
    Many newer cars have engines that can over power the brakes. Don't pump the brakes. Don't turn off the ignition. Hit the brakes and shift to neutral.

    Sounds easy but is it? Practice it first in a safe area according to Consumer Reports

    I understand that the Toyota's involved in the big recall use drive by wire accelerator control. There is no longer a direct mechanical linkage to the engine.

    I have had a gut feeling for some time that there may be more than just a carpet problem.
    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Jan 27, 2010 #2


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    Even when there is a direct throttle linkage, many things can happen when sensors fail. Lots of vehicles with direct linkages rely on throttle position sensors to to tell the fuel and ignition systems what to do. If the TPS fails, you could have over-rich or over-lean operation, stumbling on acceleration (it feels like water in the fuel system), high or low shift points, or surging at highway speeds, among other things.
  4. Jan 27, 2010 #3
    Putting the car in neutral helps in icy conditions too--well, it for me (rear wheel drive) when starting to slide. Its seems to help the car straighten out.
  5. Jan 27, 2010 #4
    Weird, my car seems to accelerate out of control all the time. . .
  6. Jan 27, 2010 #5
  7. Jan 27, 2010 #6


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    No, few, if any, do. Any car can hit the brakes hard enough to skid at virtually any speed, but unless you have a sports car, the only time you can overcome the static friction of the tires with the engine is when revving the engine and popping the clutch in first gear. Otherwise, the brakes are much stronger than the engine.

    Anyway, what is the logic for not turning off the engine? I'd rather slow to a stop without power steering or brakes than risk damaging the engine with a runaway throttle and no load.
  8. Jan 27, 2010 #7


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    Reminds me of the woman that lived across the street from me when I was little. She had a new Ford, and had just backed out into the street, then when she applied the gas pedal, it went all the way down and she ended up running into a huge tree in her front yard and died. Right in front of her family. My mother wouldn't let me go outside.
  9. Jan 27, 2010 #8
    Look at the video. The guy can not stop it at full throttle because the transmission shifts down to lower gears as the brakes try to slow down the vehicle. Anti lock brakes do not skid.

    I would probably do it the same way you would. Not shutting off the engine was recommended by Consumer Reports. Turning the key to far in the off direction would lock up the steering entirely.

    The car the guy was driving in the video couldn't be shut off at road speed. Then he realized that the button had to be pushed in for three seconds.
    Last edited: Jan 27, 2010
  10. Jan 27, 2010 #9


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    Sirens go all night here at first freeze every fall.

    My advice: Try to minimize acceleration; that is, try to minimize breaking, gassing, and turning so you can regain the friction bond between tire and road. Of course, you want to turn your wheels into the slide so they're rotation is aligned with the direction of motion (again increasing the chance of regaining the static friction bond). You don't want to slam on the breaks because then you lose all chances of friction regaining a static case.
  11. Jan 27, 2010 #10
    I have had all kinds of weird sensor problems over the years. Most of them will cause a check engine light to come on or leave a code in the CPU.

    The worst thing I had happen was to have a throttle body shaft break and leave the butterfly valve stuck half way open.
  12. Jan 27, 2010 #11


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    I haven't had a vehicle that allows the ignition to be turned off to the point where the steering wheel locks up unless the vehcile is in park or if it is a stick-shift, there is a small lever on the side of the steering column that has to be pushed to get the ignition switch to go to the point that the steering wheel locks.
  13. Jan 27, 2010 #12


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    That's morre or less (not exactly, though...) what he says, but the video shows the spedomeder needle going down when he does it.

    Perhaps the problem they are really after is that the car doesn't decelerate fast enough when you just slam on the brakes?
    Actually, they do, but that doesn't have anything to do with the point. You don't need to apply the brakes hard enough to skid in order to overcome the engine's torque.
    True, but unless you have to make a new turn between the time you apply the brakes and the time you get to a complete stop, that doesn't hurt you any. We're only talking about up to 3 seconds, here.
    Frankly, that was another part of the video I didn't like. I'd expect an engineer to be enough of a nerd to know that holding a power button for 3 seconds is the standard way to turn off any device with a multi-function power button (try it with your computer and your cell phone). It's the next thing that would come to mind for me while standing on the brakes and decelerating...
  14. Jan 27, 2010 #13


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    That's a good point and one I didn't think of. I had to go test it on my Mazda to be sure: you have to push the key in while turning to get to the last position. Trouble is, that fact is so burned into my subconscious that I do it all in one motion without thinking about it. In an emergency situation, I'm not sure if I'd do it or not.
  15. Jan 27, 2010 #14
    You are right I wonder how Consumer Reports missed that, especially a test driver. I checked my Honda van, I can turn the key off in neutral but not to the point that it locks.

    The recall goes back to the 2002 models. Did they have this safety feature??

    So it would appear that only power steering would be lost. That might be difficult for some people to handle. I have actually experienced a sudden loss of power steering at road speed. I handled it OK but it was one heck of a surprise.
  16. Jan 27, 2010 #15
    True but he could not get the vehicle to stop. The slower the vehicle goes the lower the gear that the tranny will shift into.

    Again at road speed anything that affects braking is too slow for safety

    3 seconds From 80 mph ?? Not all of these incidents are in parking lots. At speed there is a lot of brake fade even with disk brakes when dragging against an open throttle.

    I have a link somewhere showing a little 4 cylinder Chevy HHR that had brake fade before they could get it stopped under full throttle.

    This three second thing is fairly new in vehicles and the directions are in the owners manual. The test driver did mention that and was aware of it.

    I read my owners manual and I know you read yours but not everyone does. My wife can't even program the radio stations.
  17. Jan 27, 2010 #16


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    This weekend, my girlfriend's car was having trouble that caused it to stall out when trying to idle. It stalled when I was making a left turn in traffic, shifting from first to second. I didn't try to steer, kept going in the turn and popped the clutch when I dropped it into second and it started right back up.

    Point being, it is important to be able to keep your head in trouble situations in a car. They aren't usually that bad if you just relax and take it slow.
  18. Jan 27, 2010 #17
    http://blogs.consumerreports.org/cars/2009/10/toyota-recall-putting-stuck-floor-mat-survival-strategies-to-the-test.html [Broken]
    Last edited by a moderator: May 4, 2017
  19. Jan 27, 2010 #18
    Yea but all people aren't as perfect as you and I and the PF'ers are Russ. o:)
  20. Jan 27, 2010 #19


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    We don't know any of that from watching the video - he didn't show it. I expect that the car will continue to downshift until it stalls out in first gear.
    [edit: you found a link confirming what I said - a car will stop if the gas and brake are both pushed]
    Ehh, I'm not really buying that. Why do you need to do a slam-on-the-brakes stop anyway? Heck, if this happens on a highway and you use his method, it just seems to me to be a good way to get rear-ended!
    Obviously it depends on the speed you're going. From 80, it is probably around 6 seconds.
    Yes, it is new - pusbutton starting is new. And yes, I read my manual, but heck, if a car had a new feature I'd never seen before, I'd hope everyone would read their manual!

    In any case, my point is that there are an awful lot of people out there who would know intuitively that a 3 second hold is how to turn off a car with a power button(and certainly any young engineer should) . His characterization that this is some arcane knowledge is just plain inaccurate.

    Heck, in normal everyday situations, how do you turn off the car? Is it different when it is moving than when it is in park?

    Either way, 3 seconds is probably too long to wait for the car to shut off in some cases, so I might not be inclined to use that method for such a car.
    Last edited: Jan 27, 2010
  21. Jan 27, 2010 #20


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    Yes, that link confirms what I said in my first post: most cars will stop if you push both the gas and the brake to the floor. The brake is a lot stronger than the engine.
    Last edited by a moderator: May 4, 2017
  22. Jan 27, 2010 #21
    In the situation in the link below the driver actually made it to the Toyota dealership with engine still reving. Odd that they didn't find a fault code:confused:

  23. Jan 27, 2010 #22
    It depends on how much weight you can put on that brake pedal.


    Edit: I haven't seen this web site before so I can't vouch for its credibility. I'll check it out.
  24. Jan 27, 2010 #23
    There was a relatively recent incident here in California where a family had their vehicle accelerate out of control apparently on a downhill grade that eventually took the car right into a brick wall at full speed. They all were believed to have died instantly upon impact. There was speculation that a known issue of the floor mat catching and holding down the accelerator was the cause of the accident.

    They called 911 when they realized that they could not figure out how to stop the car and that it was headed for a T-intersection. They played the recording on the news. It was rather sad to listen to.
  25. Jan 28, 2010 #24
    drive by wire has got to be the dumbest thing toyota has ever done. painfully stupid, really. at least with my mechanical linkages, i've got several tools at my disposal, and am unlikely to have everything fail at once. i can shift the transmission into neutral, depress the clutch pedal, apply the brakes, take my foot off the accelerator, AND i can still cut the power to the ignition and not lose steering.

    it almost sounds as if they've either got one box controlling it all, or linked them in such a way as to override independence. if they had any sense at all, and were still determined to do this, then at least use a distributed control system and maybe even redundancies on those. geeze, i bet they run it on a microsoft OS, too.
  26. Jan 28, 2010 #25


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    Turning off the ignition while the car is moving is just a really bad idea, considering there's so many other less drastic options. You'll lose your power steering and you'll lose your power brakes.

    Once in a while, you hear of some tourist that overheated his brakes coming down Pikes Peak that thought turning off the ignition on the way down a mountain was a good idea. The accounts of people driving up the mountain of a silent car rolling down the hill with little terrified faces pressed desperately against the window are just too poignant. You never get the account of the people that were actually in the car, since they inevitably miss a turn and roll 2 or 3 miles down the steep mountain side, scattering body parts all along the way. Well, almost like that.

    Better options:

    1) Surely your emergency brake is in proper operating condition. I know everyone, even those with automatic transmissions, religiously use these when they're parked and that everyone religiously washes the underside of their car, even in the winter.

    2) Downshift. Even an automatic transmission has low gears.

    3) Once the speed has decreased enough, you can put the car in neutral. Just wait until you're already going slow - the braking action of a lower gear would be preferable to neutral at higher speeds, since neutral won't actively slow you down.

    4) If all else fails, shift into reverse. Your transmission and drive shaft will be totally and completely trashed, but it's still a better option than turning off the ignition.

    Just another reason automatic transmissions should be banned. They automate things to the point that not only do drivers not bother to drive anymore, they don't even remember how.
    Last edited: Jan 28, 2010
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