Toyota uncontrolled throttle 6

[thruthefence]

Regarding the Toyota troubles currently in the news; any chance of this being a "drive-by-wire" software (or hardware) issue, as opposed to a strictly mechanical, binding throttle linkage,ect problem?

 

[MacGyverS2000]

Everything they've distributed so far points to a mechanical issue.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MacGyverS2000]

To be more specific, they're "solution" is to shorten the pedal linkage, most likely in a bid to prevent it getting too close to the ground and caught on something (e.g., mat).

Dan - Owner

http://www.Hi-TecDesigns.com

 

[evelrod]

Dan, I just gotta disagree with the mechanical only problem. It very well 'may' be, but over 2000 incidents and 22 deaths hardly indicates a 'mechanical only' solution!
Something that simple would not necessitate the complete shutdown of so many model lines and the suspension of all sales. Something fishy?

Rod

 

[MacGyverS2000]

Rod,

They did suspend all sales, as of yesterday, I believe. It affects 8 models, 2009-2010 model years.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MacGyverS2000]

Oops, sorry, I read your reply in the wrong light.

They're sending notices for people to bring the cars in and have them retrofitted with a new linkage as an immediate solution. Now, whether or not they also play with the ECU I cannot say.

This is going to be a nightmare for them. Since they have asked people do not continue to drive the car until the repair has been applied, they may have to pay for people to have their cars towed in, and that won't be cheap by any means.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[MacGyverS2000]

Some more info, directly from Toyota's site:

Toyota has investigated isolated reports of sticking accelerator pedal mechanisms in certain vehicles without the presence of floor mats. There is a possibility that certain accelerator pedal mechanisms may, in rare instances, mechanically stick in a partially depressed position or return slowly to the idle position.

Toyota’s accelerator pedal recall and suspension of sales is confined to the following Toyota Division vehicles:

2009-2010 RAV4,
2009-2010 Corolla,
2009-2010 Matrix,
2005-2010 Avalon,
Certain 2007-2010 Camry,
2010 Highlander,
2007-2010 Tundra,
2008-2010 Sequoia

The sticking accelerator pedal recall is separate from the on-going recall of Toyota and Lexus vehicles to reduce the risk of pedal entrapment by incorrect or out of place accessory floor mats.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[evelrod]

Some recalled models all the way back to 2007 and 2005 (Avalon).

Like I said, very suspicious. Hard to believe they cannot find the problem and it's going to cost in the $billions...

Rod

 

[GregLocock]

Figure on $100 per car at least. Ouch.

This is distinct from the drive by wire issue, I guess.

What's odd is I see reports of cars that accelerate by themselves, not just refusing to slow down (althoughI'd agree that if you are unnerved they might feel similar).

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[evelrod]

The "local" incident from the newspaper was a gentleman that managed to get his car to the dealer with the brakes smoking and the throttle at full song. No details...Certainly lends new meaning to "unintended acceleration", though.

Rod

 

[ChrisDuncan]

I think it's a "drive-by-wire" issue. Mechanical throttles reached near optimum refinement of design a long time ago. Electric throttles have not. Where in history has there ever been this type/magnitude of problem with mechanical throttles?

This is a perfect storm of a problem probably caused by over-engineering (going from mechanical to wire), or lack of redundancy under engineering (like not having 2 pedal sensors and 2 throttle sensors that all have to agree or it fail-safes). It's compounded in some cases by the fact it's not quick and easy to turn the key off. Like in the case of the Lexus with the remote key-fob.

The accidents also illustrate a probable lack of driver education in this country. Like shift into neutral or, full brakes trump full throttle.

 

[patprimmer]

Neutral and let the rev limiter look after the engine while I look after me would be my option.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

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for site rules

 

[MacGyverS2000]

Chris, full brakes only trump full throttle on a car that isn't already barreling down the highway. If you're at speed, the brakes have to contend with not only holding back the energy being provided by the engine, but the inertia already in play as you fly the friendly skies at 70mph. Some brake systems are up to it, some aren't. I imagine trying to shed some speed, followed by letting up on the brakes to see "if it fixed things" is another problem (driver education again)... do that a few times and you've already begun to stress the brakes, like continually riding them while rolling down a mountain highway.

An interesting LA times article from a couple of months ago:

http://articles.latimes.com/2009/nov/29/business/la-fi-toyota-throttle29-2009nov29

Dan - Owner

http://www.Hi-TecDesigns.com

 

[Fmangas]

Pat
That gave me quite the chuckle this morning. You're absolutely right

 

[NormPeterson]

Chris - my understanding of Ford's DBW is that there are three separate traces in the pedal sensor mechanism, and in one of which the direction of increasing resistance is opposite to that for the other two. You'd expect Toyota to be using at least two.

You can train people to more-or-less follow the rules of the road and to present at least a semblance of obedience to posted signs. I'm much less sure that you can teach presence of mind while under extreme pressure.


Norm

 

[evelrod]

Okay---I fully understand everyone's position on brakes, throttle, etc. I have had experience with stuck throttles a time or two...easy remedy IF you have the time...BTDT!

The "problem" with the local Toyota that I posted was that not only were all the brakes smoking and the throttle stuck, the trans was stuck in gear...Neutral could not be engaged!
Lucky man. Slow speed problem. Dealer close by. Ok? Well put that scenario into a car at 70+. Even an experienced driver would have problems---Pretty much as the CHP instructor and his family in the Lexus?

Way more to this than is being made public so far. You just do not recall 2.3 million cars, shut down six mfgr facilities in two countries and cease all sales because of a mechanical issue!

Rod

 

[GregLocock]

My guess is that they did a proper FMEA, uncovered a lot of slightly grey areas, and are dealing with all of them. it seems the throttle pedals in this recall are from one supplier in particular. That always burns. As an example in the Explorer/Firestone issue, almost all the tires that failed were from a different factory brought online to support full production. Once the Feds saw that evidence the main case evaporated.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

 

[msquared48]

They've had anti-lock brakes for years. So, adapt the same technology to the gas pedal. Like...duh...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[MacGyverS2000]

Why they didn't add code that made the brake pedal override any gas pedal input is beyond me. If a driver steps on both pedals at once (or the ECU thinks that's what happening), give the safer alternative precedence.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[NormPeterson]

Mike - ABS still retains the direct hydraulic connection between the master and wheel cylinders, but DBW is just a few wires. Perhaps brake assist might be a closer analogy to DBW.

Instituting a direct mechanical throttle "backup" linkage would likely put mechanical throttle positioning in conflict with where the DBW is trying to tell the throttle motor to put it. If either is given override authority over the other, the 'other' then becomes pointless.


Dan - at least one or two cars are already set up this way (and are reportedly somewhat frustrating to drive under certain circumstances). There are a few situations where brake and throttle use can overlap, either accidentally or by active intent, and in which electronically commanding a throttle cut might not be the best answer either. Electronic "sensing" is still a matter of inference from that which has already happened rather than direct observation and correlation to experience.


Norm