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Unintended Acceleration -- While Parking

Discussion in 'Gen 3 Prius Main Forum' started by evpv, Dec 29, 2010.

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  1. evpv

    evpv Active Member

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    They are speculating you might be experiencing grippy friction brakes while backing up. Grippy brakes are a slight nuisance caused in part because the Prius rarely uses the friction brakes. Kind of like a normal car that has been sitting in the rain for a week. The brakes grab until they get hot enough to wear off the rust and lubricate the rotors.

    If you really feel like your car accelerated then it's not the same thing. That would be unintended acceleration and it is a serious safety problem if it's really happening.
     
  2. 32kcolors

    32kcolors Senior Member

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    Waitress’ iPhone alarm failed, getting her fired - BostonHerald.com
    "We loved her. She was a great employee." Yeah, right. More like, they've been wanting to fire her and used it as an excuse.

    I re-read your post and it still sounds exactly like the grabbing brake in reverse syndrome. Many of us have reported that it happens after the car has been driven around/is warm, exactly as you described. Moreover, taking the foot off the brake pedal and reapplying it cures this syndrome. Tons of threads on this so do a search.
     
  3. 2010prius5

    2010prius5 New Member

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    We all know that when the ICE kicks in it adds a tiny little surge. Ever so slightly when it first starts. I do not have a problem at all with that. My concern was that as I smoothly backed out of the garage with foot on brake just maintaining slow reverse speed (clean smooth ungrippy pads with no rust on a dry day that were sitting for 45 minutes and not hot pads and rotors) as the ICE started an ever so slightly "normal" bit of additional power, the brake completely went dead, doing nothing until it rocked my heel back and immediately reapplied brakes. It's was exactly as if when ICE started a signal was interrupted to brake computer, and as I reapplied brakes it reset signal. My feeling was that pushing harder on dead brake would do nothing so I naturally just pumped the brake one time is all. Very simple concept. There was no grippy anything, no wet anything, no sudden large uncontrollable surge, but a signal interruption as ICE started. Unpleasant feeling because there is a very tiny difference in power sometimes when ICE kicks in and this was what happened. Not concerned on the ICE assist, but the loss of brakes/brake signal.... Please let me know if I need to state it a different way. I was not on accelerator only riding brake on extremely small incline down backward that is ever so small. Was in Dallas, 80 degree sunny day, dry, no rain, 2:45pm ish, car driven 45 minutes earlier and parked in my garage. New car, 1500miles, clean, dry rotors and brake pads with no moisture or rust... ICE started as I pulled about 2/3 of way out of garage.
     
  4. 32kcolors

    32kcolors Senior Member

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    The OP of this thread claims it only happens on an incline.

    If it still doesn't sound like that's what happened to you in either of these two threads and you didn't mess with the Hill Start Assist, then you have a completely different problem and better have the dealer check it out.
     
  5. 2010prius5

    2010prius5 New Member

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    Nope, never set parking brake. Garage slab is perfectly level. Happened as cars back wheels were fully out of garage and front aligned with garage door. At that point ICE started, brakes were done (not doing anything any longer while still ciasting back on them and thats when I reapplied brakes. Ever so gradual slope. Ball or car would very slowly roll, not really picking up speed into parked cars behind. Not a hill, just enough something would roll back in that direction slowly until it would hit it. Brakesjust quite when ICE started/engaged did not strongly jump back, but had to take foot off brake and reapply to get anything was how it felt. Felt like a signal problem. No grippy stop, jerkiness, etc... Just lost braking momentarily as if signal lost to brake computer... I'll see about brining it in. It has only happened that one time right around 1500 miles. Close to 4000 now in two months. Not really any continuing issues accept still trying to understand the fraction of a second loss of braking feel on uneven surface that dies not feel the same as on other ABS equipped cars. Same question was asked in another thread. Something to do with regenerative braking? Anyone?
     
  6. Thai

    Thai Prius Neophyte

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    It is so strange reading these forums...you get so many weird stuff happening to other folks. I back out of my garage everyday since i bought the Prius in April 2010. Never once did i ever experience any braking issues nor surge nor UA. Weird.
     
  7. Downrange

    Downrange Active Member

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    People do not understand because they don't want to understand. Their mind is made up - don't confuse them with extraneous facts. Another word for it is "denial."

    I can count on one hand the number of time I've "accidentally" touched the gas instead of the intended brake, and, each time, the result was I rapidly removed my foot and applied the brake. I never, ever, came even remotely close to hitting anything. This is in forty years of driving. To say that all these instances "must be" driver error is worse than denial, and borders on insanity.

    This car has very complex systems, and complex systems are prone to "one-off" types of failures, often very difficult to duplicate. People who don't get this, just don't have much grasp of technical concepts.
     
  8. impact10

    impact10 Junior Member

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    And they happen with all manufacturers cars. Every single one.

     
  9. impact10

    impact10 Junior Member

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    So, what the government has to do with all cars is install that way cool camera by your foot to monitor your driving. And, another behind the driver to make sure you don't take both hands off the wheel.

     
  10. fuzzy1

    fuzzy1 Senior Member

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    So true.
    The same applies to saying that nearly all of these instances "must be" a fault in the car.
    Humans are also very complex, and proven repeatedly to be quite prone to error.

    Previous studies of unintended accelerations have found patterns that make sense only if a considerable majority of events are purely driver error. This was true even in the days when some events were being verified as mechanical failures, e.g. broken springs, jammed or pulled cables, or throttle valve icing.

    After experiencing a driver-induced incident (no damage), I now look for certain evidence to separate car faults from driver faults. Unfortunately, pro or con, it simply is not appearing in these many reports.

    For any single event, that absence means nothing. But for an ensemble, it raises a troubling statistical question -- how does the car know which drivers will notice this evidence, and which ones won't, and preferentially target the latter?
     
  11. evpv

    evpv Active Member

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    Nobody is saying the car only targets people who won't notice it. Complaints have been received from all sorts of drivers. If unintended acceleration is really happening, most people will recognize it as a problem. Read nylion's account:

    http://priuschat.com/forums/gen-ii-...nintended-uncommanded-acceleration-issue.html
     
  12. 32kcolors

    32kcolors Senior Member

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    Unless nylion was a compulsive liar and was trying to Sikes us. He created that thread after three years of not posting and only right after a big article on the safety record of Prius got published. Pepsi scare anyone?

    At least he did get a Gen III out of it, just as Sikes wanted to unload his Gen II.
     
  13. fuzzy1

    fuzzy1 Senior Member

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    You misunderstand or misrepresent my question.
    Do you mean this? His problem was different, his brakes worked very well:
     
  14. 32kcolors

    32kcolors Senior Member

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    You will not ever experience the known issue of grabbing brakes in reverse if you only back out of your garage in a cold car as it only happens if you start the car again shortly after it's been driven, but even then, don't count on being able to reproduce this issue.
     
  15. fuzzy1

    fuzzy1 Senior Member

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    I must also lodge a formal complaint against how you 'quoted' my post. By cutting my sentence in half and adding your own capitalization to the first retained word, with no preceding ellipsis, you materially misquoted me.

    Here is the original with better context:
     
  16. evpv

    evpv Active Member

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    After reading his thread I can't imagine a more genuine and intelligently written account. For you to question if he's a compulsive liar, serial killer etc. is just ridiculous.

    He didn't "get a Gen III out of it", he traded it in to Toyota for $14,000. That's less than half of what he paid for it after just 3 years and less than 40k miles.
     
  17. evpv

    evpv Active Member

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    No, I mean his original post:

    "Yesterday I was on a surface street and stopped at a light. When I gently lifted my foot from the brake to start the car rolling, the car revved the ICE and acted as though I had floored the accelerator (my foot was still on the brake and I hadn't released full pressure yet. When I pushed hard on the brake, the car stoped and the ICE stopped reving, repeating gently easing up on the brake made the same thing happen again."

    If he didn't react quickly by mashing the brake his car could have caused a serious accident. Read his thread.
     
  18. fuzzy1

    fuzzy1 Senior Member

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    ^^^ Are you saying that his post in #185 of that thread, and several other posts on the same page, describe a different event? I read it as the same event.
     
  19. bisco

    bisco cookie crumbler

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    i thought it was the same event in several different posts, but it is possible it was different events in several of the same posts.
     
  20. evpv

    evpv Active Member

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    He's saying if he didn't quickly and firmly stomp on the brake pedal the car would have accelerated on its own without his foot being on the gas. That should never happen. It is dangerous. He was concerned for his safety. He got rid of the car because he didn't trust it.

    In his case the engine revved without his foot on the gas, but the brakes held it back. In other cases people say the engine revved without their foot on the gas, but the brakes didn't stop the car. Same original problem, slightly different secondary results.
     
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