Toyota's runaway-car worries may not stop at floor

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Originally Posted By: mechanicx
-The engine will not overpower the brakes but as the article mention at WOT you might lose assist and must press hard.
Good points except for the above. Big engine will overpower brakes at WOT as brakes will quickly fade. This has been shown many times by many people and recently by Consumer Report test. BTW, have you driven a car with the Toyota's 3.5L V6 with 270 HP? Let me tell you, it's more powerful than you can guess.
 
Originally Posted By: brianl703
Originally Posted By: friendly_jacek
suggests to me that the nature of the problem is that ECU freezes at WOT and stops accepting inputs from sensors.
One solution to the problem of a "freeze" is a watchdog timer circuit. The software must "pet the dog" a certain number of times per second. If the "dog" isn't petted (because the software has crashed) he "barks" and kills the power to the computer.
Great Idea. I studied Toyota's ETCS-i and it has a few redundancies built in: doubled gas pedal sensor checked against a doubled throttle position sensor and controlled by a doubled processor. If problems arise, the ECU turns the throttle motor and it's electromagnetic clutch off and a spring forces the throttle to close . MIL would be illuminated and the engine would work only at idle speed. This sounds great on paper, but were don't know if the system is watched for software freeze. Another complication is the fact that ETCS-i has a built in cruise control. What if the signal to accelerate to 120 mph came from the faulty cruise control circuit? If so, the redundancy in the ETCS-i would not matter much, as discrepancy between gas pedal and throttle is expected with electronic cruise control. One would think that cruise would normally be canceled by braking, but again, we are talking about malfunction. We all know that any PC and any software could freeze or malfunction. I'm annoyed by Toyota's position that their system is perfect and the blame is square at the driver or floor mats. This is an interesting story I found showing that mats are not an issue and how dealership reacted to the problem from http://www.toyotanation.com/forum/showthread.php?t=314465
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My 07 Rav has repeatedly gone from speeds around 30-35mph in town to 90mph unexpectedly and rather quickly with the cruise control off. I do not have floor mats. The best I have learned to do since this happened to me 6 times now is to shift it into neutral even at high speeds. In my case when I did that the engine still kept reving higher but was out of gear. With both feet on the brakes the Rav just kept increasing speeds and when I was able to get to a safe spot only then did I shut off the engine. If you shut the engine off you wil llose power steering and power brakes which are critical at high unintended speeds. My Rav only has 10,000 miles on it and everytime I brought it to the dealer they said there was nothing wrong. Yesterday I brought it in for a routine oil changeto the same dealership and when I came to pick it up out of the blue they said my Rav was too dangerous to drive and would not let me take it home. They gave me a free rental "til the problem is resolved" but would not answer why the sudden change of heart. I suspect that when someone drove it in or out of the garage it took off on them and scared the daylights out of them like it does me. They are sending a Toyota master mechanic from another state to come and look it over next week. I am not in the loop on what if anything they suspect is wrong or what will be done to correct the problem.
 
Originally Posted By: friendly_jacek
Originally Posted By: mechanicx
-The engine will not overpower the brakes but as the article mention at WOT you might lose assist and must press hard.
Good points except for the above. Big engine will overpower brakes at WOT as brakes will quickly fade. This has been shown many times by many people and recently by Consumer Report test. BTW, have you driven a car with the Toyota's 3.5L V6 with 270 HP? Let me tell you, it's more powerful than you can guess.
You took what I said out of context. I said that an engine can not over power the brakes, meaning that if you held the brakes locked, the engine could not overpower them. I went on to say though that if the engine is at WOT the stopping distance would increase, brakes can fade, and to put it in to neutral,etc. You can't take just one sentence out of context. I've driven cars with a lot more HP than 270 and more torque.
 
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Originally Posted By: mechanicx
Originally Posted By: friendly_jacek
Originally Posted By: mechanicx
-The engine will not overpower the brakes but as the article mention at WOT you might lose assist and must press hard.
Good points except for the above. Big engine will overpower brakes at WOT as brakes will quickly fade. This has been shown many times by many people and recently by Consumer Report test. BTW, have you driven a car with the Toyota's 3.5L V6 with 270 HP? Let me tell you, it's more powerful than you can guess.
You took what I said out of context. I said that an engine can not over power the brakes, meaning that if you held the brakes locked, the engine could not overpower them. I went on to say though that if the engine is at WOT the stopping distance would increase, brakes can fade, and to put it in to neutral,etc. You can't take just one sentence out of context. I've driven cars with a lot more HP than 270 and more torque.
I'm very sure there are MANY cars that will overpower their brakes, especially those that are RWD. If I sit stationary with the Mustang with the brakes on, I can overpower the rear brakes with the engine quite easily. With a sticky tire, it will push the front wheels.
 
The ONLY way that engine could have overpowered the brakes is if the floor mat jammed the brake pedal or the vacuum assist was non-existent (due to WOT). Otherwise, in top gear at 100+ MPH there's absolutely no way that engine is going to overpower the brakes. There's too much wind resistance and too little leverage from being in high gear
 
Originally Posted By: OVERK1LL
Originally Posted By: mechanicx
Originally Posted By: friendly_jacek
Originally Posted By: mechanicx
-The engine will not overpower the brakes but as the article mention at WOT you might lose assist and must press hard.
Good points except for the above. Big engine will overpower brakes at WOT as brakes will quickly fade. This has been shown many times by many people and recently by Consumer Report test. BTW, have you driven a car with the Toyota's 3.5L V6 with 270 HP? Let me tell you, it's more powerful than you can guess.
You took what I said out of context. I said that an engine can not over power the brakes, meaning that if you held the brakes locked, the engine could not overpower them. I went on to say though that if the engine is at WOT the stopping distance would increase, brakes can fade, and to put it in to neutral,etc. You can't take just one sentence out of context. I've driven cars with a lot more HP than 270 and more torque.
I'm very sure there are MANY cars that will overpower their brakes, especially those that are RWD. If I sit stationary with the Mustang with the brakes on, I can overpower the rear brakes with the engine quite easily. With a sticky tire, it will push the front wheels.
Sure you can power brake a RWD car and lightly hold the brakes to spin the rear tires, but the car doesn't really move. Ever seen a line lock on the front brakes for doing a burnout? Those cars don't have the biggest front brakes in the world. Besides my point was that if pressed firmly enough the OEM designs the brakes to be able to hold the car stationary against full engine power. The real reason people were losing assist was because they were dilly-dallying with the brakes using up the vaccuum reserve instead of pressing them hard and once (and throwing it in neutral of course-then there'd be no brake fade or loss of assist).
 
Originally Posted By: mechanicx
Sure you can power brake a RWD car and lightly hold the brakes to spin the rear tires,
I'm not talking lightly..... The rear brakes on a Ford Fox body leave a lot to be desired.....
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but the car doesn't really move.
It does with a set of ET streets on it.
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Ever seen a line lock on the front brakes for doing a burnout?
Seen one? Bud, I've been into drag racing for almost a decade now.... I've USED one. Prevents you from burning up the back brakes. They are a very useful device.
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Those cars don't have the biggest front brakes in the world.
Neither do a lot of street cars.
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Besides my point was that if pressed firmly enough the OEM designs the brakes to be able to hold the car stationary against full engine power. The real reason people were losing assist was because they were dilly-dallying with the brakes using up the vaccuum reserve instead of pressing them hard and once (and throwing it in neutral of course-then there'd be no brake fade or loss of assist).
Has this always been the case or what is perhaps glassed over 20, 30 and maybe 40 years ago? I'm thinking there are a LOT of old cars, particularly muscle cars that could overpower their tiny rear brakes......
 
My 08 Lexus ES350 will almost overpower the brakes at WOT. I would imagine after 2-3 tries they would fade pretty fast and be red hot.
 
Originally Posted By: OVERK1LL
[quote=mechanicx] Sure you can power brake a RWD car and lightly hold the brakes to spin the rear tires,
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I'm not talking lightly..... The rear brakes on a Ford Fox body leave a lot to be desired.....
Who cares about the rear brakes for the purposes of this point?? The front do most of the work and will hold the car generally.
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but the car doesn't really move.
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It does with a set of ET streets on it.
I don't think very much, but besides it's not a question of the brakes being over powered in the front but the non stock tires being out gripped by the non-stock rear tires.. Or maybe if your front tires are on ice and you have 10' wide slicks in the back? Anyway you are taking this debate to the rediculous or at least taking this on a tangent. In the first place, I prefaced my statements to most late model cars and what would be applicable to them and the runaway Toyota's which was the subject at hand, and not all cars and non-stock cars.
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Ever seen a line lock on the front brakes for doing a burnout?
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Seen one? Bud, I've been into drag racing for almost a decade now.... I've USED one. Prevents you from burning up the back brakes. They are a very useful device.
So you should know that the front brakes stay locked. But I'm sure you are going to go back what if you had a big engine and nonstock tires and on and on.
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Those cars don't have the biggest front brakes in the world.
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Neither do a lot of street cars.
That was my point that some of them have even smaller brakes than stock front brakes since they are using skinny front tires and to save weight.
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Besides my point was that if pressed firmly enough the OEM designs the brakes to be able to hold the car stationary against full engine power. The real reason people were losing assist was because they were dilly-dallying with the brakes using up the vaccuum reserve instead of pressing them hard and once (and throwing it in neutral of course-then there'd be no brake fade or loss of assist).
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Has this always been the case or what is perhaps glassed over 20, 30 and maybe 40 years ago? I'm thinking there are a LOT of old cars, particularly muscle cars that could overpower their tiny rear brakes......
I don't know but I would say it's been the case for well over 30 years now maybe 40 considering there really hasn't been much change in them besides antilock and more use of disk brakes in the front since the early late 60's/early 70's. The thing is for a production car to be able to over power it's brakes would mean the braks are way too small and not very many automakers would bother with putting inadequately sized brakes on a car after all the lawsuits in the 60's.
 
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Originally Posted By: PT1
My 08 Lexus ES350 will almost overpower the brakes at WOT. I would imagine after 2-3 tries they would fade pretty fast and be red hot.
I think you would have to be moving at some speed before they would fade, which I acknowledged. If you braked hard once and kept the brakes at impending lock up, they might not fade, especially if you did this at the first sign the car was running away. I think these drivers were dilly dallying with the brakes and pumping them causing them to fade and to also lose their vaccuum assist reserve, let alone not putting the car in neutral or shutting the engine off.
 
Originally Posted By: mechanicx
Who cares about the rear brakes for the purposes of this point?? The front do most of the work and will hold the car generally.
If you are moving, then I would say it is a real concern. Locking up the fronts while the rears are still under power, with the brakes unable to overcome the power of the engine is going to make for a vehicle that is out of control. That is why I brought up rear brakes. On an FWD vehicle, where the larger brakes are also on the power wheels, this SHOULD be much less of an issue.
 
Originally Posted By: OVERK1LL
Originally Posted By: mechanicx
Who cares about the rear brakes for the purposes of this point?? The front do most of the work and will hold the car generally.
If you are moving, then I would say it is a real concern. Locking up the fronts while the rears are still under power, with the brakes unable to overcome the power of the engine is going to make for a vehicle that is out of control. That is why I brought up rear brakes. On an FWD vehicle, where the larger brakes are also on the power wheels, this SHOULD be much less of an issue.
That's true that you don't want to lockup the brakes, but most the newer cars have antilock brakes. Without ABS, you want to try to stay at impending lockup, but that would be too much to ask for a none expert driver. You are still saying though that the rear brakes can't stop the engine and I still disagree. like someone else mentioned the car would be in overdrive at speed.
 
Going back to the topic, I think Toyota is aware of the issues we discussed here. From link
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Toyota spokesman Brian Lyons said, the company is examining significant design changes. One possible remedy is to redesign the accelerator pedal to make it harder to get caught by a floor mat, he said. Another potential fix, he said, involves reprogramming the engine's computer to automatically cut power when a driver brakes while the gas pedal is depressed.
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The arrangement of those gear selections could make it difficult to shift from a forward gear directly into neutral in a panic situation, Toyota spokesman Lyons acknowledged. "I think it's possible to get the shifter confused, but I can't be sure that's what happened" in San Diego, Lyons said. "You'd be surprised how many people around here don't know what the neutral position is for."
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Lyons acknowledged that the vacuum can be depleted when an engine throttle is wide open, leaving the drivers without power-assisted brakes. "There's a standard where you have to be able to stop the car without power-assisted brakes, but obviously I don't think it includes situations where the throttle is wide open," he added
In summary:
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One remedy being considered by Toyota implicitly acknowledges what critics have been saying for almost 10 years: that the company's highly computerized engine control system lacks a fail-safe mechanism that can quickly extinguish sudden acceleration events, whether they are caused by floor mats, driver errors or even unknown defects in the electronic control system, as alleged in some lawsuits.
I agree. Toyota needs: or this:
 
Originally Posted By: friendly_jacek
Going back to the topic, I think Toyota is aware of the issues we discussed here. From link
Quote:
Toyota spokesman Brian Lyons said, the company is examining significant design changes. One possible remedy is to redesign the accelerator pedal to make it harder to get caught by a floor mat, he said. Another potential fix, he said, involves reprogramming the engine's computer to automatically cut power when a driver brakes while the gas pedal is depressed.
Quote:
The arrangement of those gear selections could make it difficult to shift from a forward gear directly into neutral in a panic situation, Toyota spokesman Lyons acknowledged. "I think it's possible to get the shifter confused, but I can't be sure that's what happened" in San Diego, Lyons said. "You'd be surprised how many people around here don't know what the neutral position is for."
Quote:
Lyons acknowledged that the vacuum can be depleted when an engine throttle is wide open, leaving the drivers without power-assisted brakes. "There's a standard where you have to be able to stop the car without power-assisted brakes, but obviously I don't think it includes situations where the throttle is wide open," he added
In summary:
Quote:
One remedy being considered by Toyota implicitly acknowledges what critics have been saying for almost 10 years: that the company's highly computerized engine control system lacks a fail-safe mechanism that can quickly extinguish sudden acceleration events, whether they are caused by floor mats, driver errors or even unknown defects in the electronic control system, as alleged in some lawsuits.
I agree. Toyota needs: or this:
I do agree with you that they need either to make the pushbutton ignition kill the engine instantly and/or have a separate quick kill switch. The problem with a separate quick kill switch is if someone is too out of it to tap the car in neutral maybe they are too out of it to activate a separate kill switch. I really don't know why Toyota would put that 3 second delay in the pushbutton ignition, since a key can be turned off instantly. Since it's intuitive to most ever driver to be able to kill the engine instantly with a key even while driving, you'd think Toyota would've emulated the key's functionality. Since it would be intuitive for most drivers to hit the ignition button to kill engine in an emergency, why not just get rid of the 3 second delay for starters?
 
The Start/Stop button on the Lexus is actually very close to the LCD display for central dash controls. If Toyota had a press once for full engine stop when the vehicle in moving, what is stopping an adult or a child from accidentally pressing that and stopping the engine, with loss of power steering and vacuum assisted braking? Won't that potentially lead to an accident too?
 
I don't know, but that sounds like a bad spot for an ignition button. Maybe they should move it close to were standard ignition switches typically are? Maybe change the keyless start button to a rotary switch that emulates a key in an ignition. The 3 second delay still seems like a bad idea to me. Anyway, stopping an engine while driving and losing assist isn't the end of the world. It's not that hard to steer a rolling car. You can't make a car completely idiot proof. Every driver should know how to throw a car in neutral so as to restart it or to disengage from a runaway engine. None of that excuses Toyota's throttle defect or the dumb 3 second stop delay though.
 
Originally Posted By: mechanicx
I don't know, but that sounds like a bad spot for an ignition button.
It is not a bad spot for the button. It is a fine location. The guy didn't know about the 3 second shutdown. You could move the button to timbuktu and if he didn't press it for 3 seconds the engine won't shut down. They don't need to make any of the silly suggestions on here other than fix the cause of the ETC accelerating on it's own. It has to be in the software/firmware module because it is happening across several platforms.
 
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The computer does NOT need to control the throttle! THAT is the god dam& problem! I absolutely hate that system. Give me a real gas pedal with a real throttle cable! W T F are these companies thinking? Our 2007 GMC 2500HD has this [censored] and it SUCKS! My friends yota has it and he says it SUCKS. I dont really know anybody that has it that doesnt complain about it when it is brought up.
 
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