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Toyotas Suddenly Accelerate; Owners Up In Arms
cyclocommuter writes "Some Toyota owners are up in arms as they suspect that accidents have been caused by some kind of glitch in the electronic computer system used in Toyotas that controls the throttle. Refusing to accept the explanation of Toyota and the federal government (it involves the driver's-side floor mat), hundreds of Toyota owners are in rebellion after a series of accidents caused by what they call 'runaway cars.' Four people have died." The article notes: "The National Highway Traffic Safety Administration has done six separate investigations of such acceleration surges in Toyotas since 2003 and found no defect in Toyota's electronics."
You get more MPG if the odometer is tied to a speedometer that is calibrated to show a higher speed, and thus greater distance traveled.
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IEEE Spectrum: "How hard should it be to stop a runaway luxury car?" http://spectrum.ieee.org/blog/computing/it/riskfactor/how-hard-should-it-be-to-stop-a-runaway-car
IEEE Spectrum: "This car runs on code" http://www.spectrum.ieee.org/green-tech/advanced-cars/this-car-runs-on-code
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I have owned many Prius's. I currently drive a 2010 one. Let's say that I'm in some place where the speed 85 mph is legal. I can nudge my cruise control speed lever and my speed barely goes up, say from 80 to 81.I nudge at again and again, up to 83. Then I nudge it again and the car takes off, no speed limit. Nudging the cruise speed control lever down has no effect until I've done it about 10 times or more. By then my Prius is doing 97. It's scary because it's so wrong and so out of your normal control. I tested this over and over the night I observed it.
It's scary because you don't think of things like putting the car in neutral when this happens. I am sure you can't turn the car off with the keyless power button, the only option on this model.
Braking does disable this scary cruise control effect. It is a natural response, so the problem is mitigated a great deal.
I have not seen this happen before so I think it's new to the 2010. I have the package which includes parallel parking assist and cruise control distance limiter.
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Toyota has a serious problem. Have for years. It's not the floor mats.
I was driving a '98 Toyota Camry. Foot on the brake. B-R-A-K-E. Yes, I know the difference. Car in drive. Waiting for a right turn. The car revved up high. I did manage to throw it into neutral, and the engine continued to surge. Luckily I didn't hit anything. And it was pure luck.
The car did not have All-weather floor mats.
I have racing experience, and a background in Mechanical Engineering.
The reason the problem hasn't been found is that it's probably a subtle fault (like the AT&T crash back in the early '90s, or the stress concentrations in the DeHavilland Comet) and they're (by they I mean the NHTSA) probably not looking very thoroughly, due to lack of manpower. They don't do investigations of car crashes the way they do for other serious engineering failures, like plane crashes or bridge collapses.
What's happened, in each case, is that the dealer or driver put winter floor mats, either OEM or aftermarket, on top of the regular carpeted mats. What this means is that, unlike the normal mats, they're not pinned down in any way and will slide forward. In the case of the CHP officer in the rental Lexus, the dealer slapped truck mats down on top of the "normal" Lexus mats
What happens next is easy: the mat jams the accelerator pedal. What happens after that is that people panic, do the wrong things, and plow into people in front of them.
And what happens after that is lawyers.
There's no car you can buy today where you cannot overpower the engine with full braking force. Try it: stand on the accelerator with your left foot for a while, then stand on the brake. Push both down as hard as you can; your car will slow down and stop. It won't be happy about it, but it will. The drivers in this case didn't do that: they panicked and didn't press the brakes hard enough.
Nor did the slap the car into neutral or stop the car. And yes, the car could have a gated shifter or a Prius-style stick. You can also turn the car off: even with an engine-stop button, all you need to do is holdit down. Again, in both cases it requires the driver to not panic.
There's no real way around the human factor in this. I've seen drivers who two-foot drive. I've seen drivers who, when they're presented with a scary situation, take their hands off the wheel and cover their eyes. I've been in the car when a driver's panic reaction was to flail madly at the pedals with her feet and see-saw the wheel---in that case, the car rolled. While the floor mats can create a problem, and while Toyota could fix it by mounting them a little bit higher, you'll never truly idiot-proof a car until the car drives itself.
The solution to the likes of this are systems like stability control, ABS, Volvo or Nissan's Lane Departure Control and Mercedes' and Lexus' Pre-Safe crash mitigation systems: keep the car on-course and stable, allow the driver to maintain control and, if a crash is imminent, apply full braking force, tighten the seatbelts and pre-charge the airbags. Oh, and call 911.
--srj/mmv
This is a "feature" of German cars due to a law in Germany mandating that the speedometer must NEVER read lower than real speed... even if the car has non-standard wheels and tires fitted.
Porsche and BMW exaggerate speed the most, and the theory is because owners of these cars are quite likely to upsize their rolling stock (and thus make the speedo read lower). It's annoying, but it's simply in response to a legal requirement.
Car and Driver did a test on several vehicles a bit over a year ago. GM vehicles were the most accurate... around +1 mph on average.
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I used to have one of those "sudden acceleration" Audi 5000's (1979). It happened to me once and I figured out exactly what happened within five minutes. It wasn't the computer or the floor mat or anything. The accelerator pedal linkage was a solid rod which ran up a few inches from the tip of the pedal, then turned left to pass behind and above the brake pedal. If you put the arch of your foot on the brake pedal, your toes could contact the accelerator rod and depress it. Even light braking action was enough to impart enormous acceleration. The harder you stomped on the brake, the more the engine overcame the braking action. The fix was to put a metal guard plate over the rod behind the brake pedal.
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So Toyota says it's floor mat. But here's something I don't understand after reading TFA... all people who had that problem (and lived to tell the tale) insist that they were braking hard as the car was accelerating. If it were really just gas pedal stuck in a floor mat, then surely applying brake would force the car to decelerate regardless?
Funny thing about the brake. It's operated in the same way as the accelerator, and located in a place where most people don't normally look while they're operating it.
This was famously the case with Audis in the early '90s. Audi, designing for the heel-to-toe autobahn driver, put the brake and accelerator pedals closer to each other than on most US-market cars. Cue a number of reports in the US from drivers screaming, "I was mashing the pedal as hard as I could, and the car just wouldn't stop! In fact, it kept going faster and faster!"
No defect was ever found (though that didn't stop the media from demonstrating it) and the problem was only reported in the US, although the same cars were sold worldwide.
It is exceedingly easy to test the Throttle Positioning Sensor in modern vehicles. In fact, your ECU probably tests idle throttle position every time you turn the key on for a while without staring the engine. The ECU will also log 'implausible signal' for TPS that get an out of range reading, or inconsistent reading throughout the range.
You are basically correct. I have first hand hacking experience with the drive by wire throttle because my Grand Challenge team automated a Toyota Prius for the last Grand Challenge. There are 2 completely independent signals that go from 2 independent sensors on the pedal to the computer throttle component. The signals have to move in lock step with each other or the computer will detect a fault. If a fault is detected the throttle goes completely off and the car has to be turned off and turned back on to recover.
So for the throttle to stick down both pedal sensors have to fail in the same way at the same time, which seems highly unlikely to me. Or there could be a bug in the computer control section, bus as a software engineer I can assure you that that would be impossible. ;-)
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The guy apparently did try pulling the car out of gear and into neutral, but it didn't do anything (many auto transmissions are electronically controlled and have failsafe mechanisms to prevent desctruction). He also tried shutting off the ignition - but this vehicle like many other fancy new vehicles doesn't have a key ignition. It's a button, and when pressed while driving it won't turn the engine off. Buried in the owners manual is a single sentence that essentially says that in order to turn the engine off while driving, you have to hold the button down for three seconds.
Now I've never gone 120MPH on a congested roadway, but I could only guess that when you're trying to avoid hitting anything, it's not a simple task to 'reach down and pull the floor mat off the pedal'
Although recently I had the accelerator pedal stick to the floor on a 2009 F-350 diesel. It happened as I was accelerating from a complete stop. I immediately pressed the brake to the floor which prevented me from shortening the wheelbase of the Civic in front of me, but with 650 lb-ft of torque it was still accelerating. I was able to lift the accelerator with my foot and bring it back up.
Virtually all (all that I have ever worked on) gasoline cars use the vacuum created in the intake plenum to operate the brake booster. Some cars use an electric vacuum motor to maintain the power breaks in designs where there is not a consistent vacuum or not accessibility to the plenum.
If you have a leak in your plenum or vacuum booster line, your engine should run rough and your breaks will be much harder too push.
The system will never prevent the application of the breaks, but it does mean instead of having power breaks, you are relying on the mechanical advantage of the pedal and your own leg power to stop the car. If you go back to the 60's you'll see "Power Brakes!" as an option you could add to your car.
Another option to shut down the cruise would be to put the car in neutral. If the engine continues to rev uncontrolled, it likely isn't the cruise control that is at fault.
I have experienced 3 sudden acceleration incidents. 1 was in my Fiero when the 15 year old Cruise Control vacuum got stuck (turning off the CC restore normal driving) and the 2 others, in a '87 Dodge Raider and an '06 Golf TDI we both due to floor mats not being properly installed. The velcro backing on the Dodge's mats had worn out, and the dealer threw in rubber mats on top of the stock mats in the Golf. In both cases the mats had crept forward enough to interfere with the gas pedal.
I'm not saying that there isn't a problem with any specific design, but in my personal experiences the faults have tended to center around pedal interference and/or aging mechanical devices.
-Rick
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