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."

Comments

Re:Floor mat, really?

[SteveWoz]

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.

First Hand Experience

[hubang]

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.

Re:Carmakers lie

[mister_playboy]

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.

Re:Floor mat, really?

[Divebus]

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.

Re:PEBAAC

[__david__]

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. ;-)

Re:My sudden-acceleration Audi experience

[RingDev]

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