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Toyota uncontrolled throttle
6

Toyota uncontrolled throttle

Toyota uncontrolled throttle

(OP)
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?

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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
 

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

Some more info, directly from Toyota's site:

Quote:

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

Quote:

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

2
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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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.  

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

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

RE: Toyota uncontrolled throttle

Norm,

Barring burnouts and such, I can't think of a reason why someone in an automatic would need to be pressing both the gas and brake at the same time (drivers are supposed to be taught not to drive with both feet).  If the accident is hitting both pedals at once with the same foot, then the brake should still take precedence.

In a manual I see a somewhat "special" case of heel-toeing being allowed, but how often is that done in a Camry? winky smile

Tapping the brake, even accidentally, should act just like when the cruise control is on... the throttle plate is closed and the car begins to slow down.  It wouldn't come to a fast halt, but the car would begin to slow down.  If there was a failure in their programming that cause the brake pedal to be sensed when it wasn't being touched, the worst-case scenario would be a car that begins losing power... that's a stark contrast to what's happening now, continuing to apply power.  There's certainly no need to verify and/or limit speed (as some have suggested on other forums) to implement this plan of attack.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

Should you find yourself having to drive through water deep enough to immerse the brake rotors, it's a good idea to lightly drag the brakes to squeegee as much water as possible from the friction surfaces.  Obviously, you'd want to be able to use enough throttle to carry you all the way through without stopping.  You might still want to have light braking with part throttle for a short distance afterward, particularly in weather that's cold enough for ice to form.

I can also see it happening while rocking the car to extricate it from snow or, in some locales, mud.

Those are situations that anybody can encounter at any time, and are not at all associated with any sort of unusually "enthusiastic" driving.


Norm

RE: Toyota uncontrolled throttle

I "trail brake" on the race track and on occasion, the street. However, wouldn't it be pretty simple to have a transducer adjusted to a specific pressure...oh, say some significantly higher than "normal" for the throttle cut out?

This morning it seems the recall has hit Europe and Asia, too.
Even some Ford models using the same part supplier...

Dan...Having spent a lot of time in snow country, I can attest to the absolute need of brake/throttle combo.

I have one vehicle with DBW...no problems in 170,000 miles. Even so, what's wrong with conventional mechanical/cable linkage?  I've driven well over a million miles with only a couple failures and that was on race cars! Never on the street, even in my younger days and with all the hot rods I built.  Even as a teenager, I could engineer reliable throttle linkage (made me popular, too winky smile...)!

Rod
 

RE: Toyota uncontrolled throttle

The only thing "wrong" with mechanical linkages (from the manufacturer's standpoint) is they're more expensive to install than DBW.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

There are other advantages, vibration isolation, packaging, reliability, spring to mind. The cost save is quite significant, I'm guessing several dollars.



 

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

RE: Toyota uncontrolled throttle

Also potentially it simplifies crash and there is definitely a weight reduction.

So DBW is looking pretty damn good from here.

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

RE: Toyota uncontrolled throttle

As far as I understand it the issue is indeed a mechanical problem associated with the accelerator pedal itself, not the electronic actuator of the throttle plate.

The 'DBW' concept is, in modern torque based EMS applications, used for handing over total control of the engines torque generation to the ECU. With the accelerator pedal position not relating to throttle plate position but requested engine torque (or, more, recently wheel torque).

This has benefits for interaction of auto trans, ESP etc etc. It also allows the ECU to select the most fuel economic 'setting' for a given drivers demanded torque and is especially useful when there are variable camshaft position, lift, wastegate control, swirl control valves and combustion mode where a simple throttle angle does not ensure an optimum setting.

MS

 

RE: Toyota uncontrolled throttle

(OP)
Slightly OT, but generally related to the subject at hand; a question (or observation).

I drive a Nissan Frontier Pick up truck, four cylinder engine, that is really kinda 'gutless'. I have noticed (and this is strictly subjective) that when I am on an ascending on-ramp, attempting to accelerate & merge with traffic, the truck 'feels' like it has much more power. It just seems to 'pull' and move right on out. It never makes the downshift to a lower gear. It seems to be a "sweet spot" as I add throttle, and accelerate up the on-ramp. Now, I am an old fart, and have driven my share of hot rod cars, in my time. This feels similar to another carb being activated with progressive linkage, or my old Volvo's turbo coming on speed. For some reason I don't notice it when overtaking & passing on a straight road.

Is the ECU clever enough to recognize "ascending on-ramp merging traffic" mode? I'm tempted to plumb in a manifold pressure gauge just to see whats happening during the 'event'.

 

RE: Toyota uncontrolled throttle

Thruthefence, I've noticed a similar effect on low powered cars. They are surprisingly peppy at low speed but you really notice the lack of power in high speed acceleration. The reason would be that much of the engine's power capability is already being used just to maintain a high speed, with little additional power to accelerate.  

RE: Toyota uncontrolled throttle

That must be why my little '58 948cc Sprite was a kick ass rocket around campus but totally died at 80 on the highway!

Sorry...I apologize...I just couldn't resist...<snicker>

Rod winky smile

RE: Toyota uncontrolled throttle

(OP)
compositepro, that makes sense, the poor truck is pushing alot of air at 70 mph, not much margin for acceleration.

RE: Toyota uncontrolled throttle

Compositepro - throttle response itself is probably nonlinear by intent.  Exaggerating the response at small pedal positions/movements off idle at the expense of higher rpm response will make a car feel "peppier" on the test drive and in "around town" driving.  For people who rarely use higher rpms, there are few, if any, apparent downsides.


MS - the opportunity for improving fuel economy and emissions performance had occurred to me, as had the thought that automated rev-matching on downshift probably can't be accomplished in any other fashion.  The other items on your list hadn't.

As Pat has noted, what would it take to provide the driver with ultimate override authority to select 'Neutral' or otherwise disconnect the engine from the drive wheels and let the PCM worry about the engine?



Norm

RE: Toyota uncontrolled throttle

Norm, I don't believe that throttle position response is much of a factor because the driver will position the throttle pedal position to whatever is required to give the desired acceleration. As long as the pedal is not floored, the car has adequate power. It is mostly in high speed passing that I'm reminded that the car has limited power because the pedal is floored and the car in barely accelerating. This often aborts the pass and is annoying. Even driving powerful cars the pedal will be floored at the start of passing.

RE: Toyota uncontrolled throttle

The latest from Toyota (to their dealers) is that the "fix" is "in the mail"...Thursday (maybe)?

The recall has reached three continents and over 4 million cars!  Even for a "simple mechanical fix" this has just gotta hurt.

My pals at the Ford dealer are jumping up and down...Sales with late model Toyota trades are 'booming'!
I've been through a couple big recalls in years past. Suffered through Nader's trashing of the Corvair (I had a new '64 Spyder)...Never anything like this, never!

Yep, this has just gotta hurt!

Rod

RE: Toyota uncontrolled throttle

I saw a headline in today's paper that the fix was on the way now that the government had "approved" the fix.  HUH?

I agree with PatPrimmer that the solution ought to be as simple as kicking it into neutral but I think that is obvious only to guys/(gals) like us who know how things work and how to operate the equipment like we want to when that is what is needed.  When this first came to light, I, like Pat, thought what is so complicated about this.  Just dump the clutch, right?  These days, that is done by moving the stick one notch.

I was discussing this with the wife today while out driving as she had ask about the extent and nature of the problem and as a test, I mentioned Pat's solution and asked her if she would think to do this.

She said that she never would have thought of that and it was another (she has many) example of how engineers thought differently from normal people......

I shudder to think that I am sharing the road with people who can't figure out that kicking it into neutral (and listening to the engine scream) is a life saver.  I have had to do it a few times in my life for unrelated problems, and it came second nature to me.

rmw

RE: Toyota uncontrolled throttle

no matter what you can still turn the key to the OFF position.
smile never mind power brakes or steering, who needs em....
I will stick to my VW.
Oh and plz stay away from automatic wink.  

peace
Fe

RE: Toyota uncontrolled throttle

drweb, I try to keep up, difficult as that seems to be.  I have read much of what has been posted on the various sites relating to this recall.  I sure hope this is not just "smoke and mirrors"!

Rod

RE: Toyota uncontrolled throttle

Is it just me, or does that diagram explain practically nothing of use unless you are intimately familiar with how the entire mechanism works int he first place?

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

2
It looks to me that the designer has cleverly biased the friction damper with the reaction off the base of the return spring.  I would hazard a guess that the shim changes the bias somewhat to reduce the friction.

RE: Toyota uncontrolled throttle

Bit of a bummer when your design works somewhere between 99.99 and 99.999% of the time and you still cop flak over it!

Cheers

Greg Locock

I rarely exceed 1.79 x 10^12 furlongs per fortnight

RE: Toyota uncontrolled throttle

Does anyone know the type of position sensor(s) used in the Toyota CTS pedal?

RE: Toyota uncontrolled throttle

""Bit of a bummer when your design works somewhere between 99.99 and 99.999% of the time""

It's probably a bit higher ratio than that considering only 20 or so fatal accidents.

I think that's part of why it took them so long to come up with a fix, trying to duplicate or surmise the problem.

DBW is better than cable from a manufacturing standpoint due to the fact it eliminates air bypass systems. Most cable throttle EFI cars have at least one, some have 2. One for loads, one for cold start. The DBW throttle body handles both the normal throttle function and load/cold-start air flow adjustments to maintain steady idle.

The automatics with optional "manual" paddle shifters have a more complex gated console shifter, if it's in the paddle mode you have to move it over and up to get to neutral. Maybe this should be re-thought to go back to the one movement to neutral.

Still think shifting to neutral is the best thing to do, it's easier to locate and slam the shifter up, most won't go to reverse without the release button. Easier than finding and turning the key and you don't lose your power steering/brakes. It should be part of every defensive driving course. Everyone that drives a DBW vehicle should practice in a parking lot.

You don't have to worry about hurting the engine, all DBW cars are rev limited and most are rev limited to 4,000rpm when the shifter is in neutral.

Maybe a kill switch system if you're going to use the complex remote keys, sort of like a dirt bike, only one easy access fool proof switch, all it does is kill the engine. But then you have to train drivers to drive without PS, PB.  

RE: Toyota uncontrolled throttle

I would like to see information such as where the ECU is manufactured. I can relate to "computer problems", I work at a place that designs and builds, markets thier own products, that have a computer in them for control functions. I also am very well versed in CNC machine tools, that also have a computer or many computers in them for control purposes. I am not sure where the computers are made that my place of employment use, but I do know we have our share of major problems with them and some major returns of product because of them, also I very well know what happens when a CNC machine tool has a computer glitch and crashes, so for anyone to come out and say it's not a computer problem, they should reexamine the information out there. The pedal is not sticking in some of the cases.
What ever it is, it is bad workmanship from some entity.
And a shame that people lost thier lives from it.
This should be a wakeup call for mandating strict emissions standards and forcing DBW or anyother type of control that removes the drivers input to the function and transfers it to a computer.
The other latest thing is computer controlled brakes in the hybrids, whats next?

RE: Toyota uncontrolled throttle

What do strict emissions standards have to do with this?  And the problem here could very well be due to removing the driver's control from the equation.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

As emissions standards get increassingly strict, there is greater pressure to attack much smaller transient conditions which tend to give brief "spikes" in the emissions.  Once you're really 'clean' 99.5% of the time, being rather 'dirty' for much of that remaining 0.5% matters more.

Just off the top of my head, allowing the throttle to snap shut as would typically happen with a purely mechanical throttle on a vehicle with a conventional manual transmission (think upshift here) is one example where emissions performance has "forced" some alteration in the relationship between the pedal and throttle positions.  Has for a while.


Norm

RE: Toyota uncontrolled throttle

"allowing the throttle to snap shut as would typically happen with a purely mechanical throttle on a vehicle with a conventional manual transmission"

I don't get it. You mean it automatically controls the throttle for you?
 

peace
Fe

RE: Toyota uncontrolled throttle

(OP)
I think the ecu has an input for "brake application" as well as turning the lights on, coasting for a certain time frame, lots of stuff thats doesn't seeem like it's needed, but someone thought it was necessary.

RE: Toyota uncontrolled throttle

Let's just say that the effective rate of throttle closure can be electronically modulated, either slowed or briefly raised and then allowed to drop at some emissions-friendly rate.  If you'll accept the behavior of my 2001 Maxima (MT) as adequate evidence, this can even be done on a mechanically controlled throttle design, probably via the idle air bypass and its control valve (which is PCM-controlled).


Norm

RE: Toyota uncontrolled throttle

Just out of curiosity, what happens in an electronically actuated/controlled transmission when "neutral" is not recognized by the ECM?

Rod

RE: Toyota uncontrolled throttle

Norm - Early emissions cars even with carbs had anti-snap shut dampers. For example a 1988 era VW Jetta, if you accelerated the engine to 4000 rpm and released the throttle, would hang at 1800 rpm for a while, to burn off HCs at a rough guess.

Mazdas and Fords, and for that matter my Corona (Airpump/carb) did it as well. Not that it ever revved to 4000.

evelrod - nothing, or more accurately, whatever they programmed it to do. I drove 4 makes of cars and all allowed neutral to be selected while driving, two were definitely shift by wire. So until I find a car that blocks shifts into neutral I can't tell you!

dicer-virtually all computers of all types are basically built in SE Asia, statistically speaking. Especially the reliable ones.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies  http://eng-tips.com/market.cfm?

RE: Toyota uncontrolled throttle

I also think it could be some kind of outside interference.

Like an ECU will become erratic if a large amp power wire is routed in close proximity, something about electro-magnetic fields.

I've also seen cell phones clear immobilizer key chips when they are stored next to each other.

Another thing that happens is when a laptop is placed on a air bag seat occupant height sensor, it can cause erratic operation.

These critical throttle/brake electronic systems need to have the same rigorous safety measures and redundancies as the typical air-bag system. AFAIK no airbags have gone off by themselves and they are just as complex of a system.  

RE: Toyota uncontrolled throttle

"Like an ECU will become erratic if a large amp power wire is routed in close proximity, something about electro-magnetic fields."

That's EMC or EMI testing, every design of car is checked for it, but the suspicion is that this doesn't catch every problem.

Other things include degraded or failed sensors, and unusual timing loops.
  

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies  http://eng-tips.com/market.cfm?

RE: Toyota uncontrolled throttle

I would expect any firmware issues to occur in the field more frequently than we have seen - and perhaps be more easily reproducible on the bench.

It may be just the media, but Toyota's "shim" fix was quoted as being fabricated from steel.  Why not aluminum or plastic?  It there an electromagnetic function to this part as well as defeating the otherwise-helpful friction damper?

I would guess the feed signal to the pedal is some sort of high frequency voltage or current and the sensor changes the inductance.  Any knowledge here of the electrical details?

RE: Toyota uncontrolled throttle

Hmmm, all this speculation about electronic interference reminds me of the instruction to power down electronic devices during takeoff & landing on most airplanes . . .

RE: Toyota uncontrolled throttle

So, will all these Toyota's go into neutral at WOT if so shifted? I have not read that they would not so I highly doubt that neutral is locked out.

I know at least some of these cars are push button start and that requires holding the button 3 seconds to get the engine to "emergency" power off. So, these cars can be difficult to shut off in a panic situation.

So, it's the typical more than one thing causing most of the accidents. Once the throttle sticks, it's partly the driver not handling the situation well and it's partly the fact that the car can't be shut off easily which would be many persons first reaction in such a situation. Having decent panic situation training as part of the license requirements would certainly help with this problem, as well as helping in many other complete "fails" I've seen on the roads.

Greg's link shows pics of the disassembled pedal assembly and the fix looks quite plausible to me. The friction block operates via a lever connected to the return spring. The shim goes behind this lever and keeps the spring from either putting any pressure on the friction block or it limits the pressure on the friction block.
 

RE: Toyota uncontrolled throttle

Kiwi,

Steel is probably cheaper than aluminum and more wear-resistant than plastic.  No EM function...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

Well, Toyota has set a record for the most cars recalled, EVER.  Zipped right by the old Ford record of 16M...

Rod

RE: Toyota uncontrolled throttle

Damn, I still want a Supra though...bigglasses

peace
Fe

RE: Toyota uncontrolled throttle

Yes, probably a good time to buy a Toyota.

Now things get weirder, the pedal maker says that the pedal issue is not a likely cause of SUA

http://online.wsj.com/article/SB10001424052748703615904575053772190118314.html?mod=WSJ-hpp-LEFTWhatsNewsCollection

and I don't suppose this bloke from NJ believes either of the recalls would help

http://thesafetyrecord.safetyresearch.net/2010/01/12/2010-forecast-toyota-sua-problems-continuing/

 

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies  http://eng-tips.com/market.cfm?

RE: Toyota uncontrolled throttle

Just for piece of mind, I think if I owned one of the cars in question right now, I would be finding a wire that if cut, would cut of all power to either the ignition or the fuel pump, and I would install a big red safety cut out switch off an industrial machine so that when it is activated it cuts fuel supply and/or ignition at the source.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: Toyota uncontrolled throttle

Quote:



I'm a bit surprised by the number of people who don't know if they can select neutral while driving their particular car.

I have been interested in that question from the first suggestion, but have not seen it convincingly confirmed or denied, which is odd, seeing as how crucially important it is with a runaway engine scenario.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: Toyota uncontrolled throttle

The second linke Greg posted yesterday infers the Avalon can be shifted to neutral since the owner was reportedly doing it while the engine was revving. Don't know about any other models though. That article also says the tech "tried" to move the pedal but could not get the engine to quit revving.

Unless I personally have seen the problem or know someone who I trust that has seen it, I'm really not very convinced that Toyota has anything more than an issue that has been reported in a small number of cars and that they've been trying to diagnose it - as of now, they have found the pedal can stick and have concluded the pedal assembly is the problem. Only time will tell if that is so.

Once this started, the stories begin to circulate out of control. The idea that Toyota is hiding problems is great cover for the media and the lawyers love it too. Now, how many cases of people pressing the wrong pedal will just get blamed on Toyota building a faulty car?

It reminds me of the government here deciding to change the laws to add a bunch of roadside penaltes which remove the court system from the process. They used "street racing" to justify it. Just rattle on about how the law will solve the rash of street racing deaths and let the media run with it. It got competely retarded to the point that every single fatal accident was reported as "possibly street racing" that summer.

Anyone who thinks that the news media exists to report the facts is very dillusional. The news media exists to make the owners money....
 

RE: Toyota uncontrolled throttle

Looks like they just recalled all of their hybrids now due to a brake that doesn't really brake as hard as it should (something to do with the ABS system).

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

From my very first post, I have been skeptical of the "mechanical only" cause.  All this may indeed end up as an execution in mass hysteria...then again!

I have a few basic problems with ALL new cars that do not have a "key", "switch", that when activated kills the engine...RIGHT NOW, not in "three seconds".  

Relying on the brakes to save you is a fools dream.  In most cases of high speed acceleration, the brakes will simply fail if the power input cannot be interrupted by declutching, selecting neutral, kill switch or the like.

As most of you already know, I still drive race cars and have spent many years doing stupid "driver errors" that, for a non racer, could have been fatal.  The ability to save 'ur a** in a clutch situation is only learned by actually doing it or by taking a class in such maneuvers and lots of practice. It must become a "reflex action" it it is to be affective.

Bottom line...Driver education.  Common sense driver training classes in avoidance, panic, imminent crash, etc.

Too bad I do not see any of that in the future...Just more "safer cars" mandated by big brother.

Rod

RE: Toyota uncontrolled throttle

Not do defend the media, but Toyota has a history and reputation of denying most field problems and blaming them on 'user error'.  Coupled with their reputation for flawless dependability they set themselves up to some extent for this kind of fall.  There are many similarities to Ford/Firestone themes where SUV's reputation as the 'safe' vehicle was questioned in a time of economic anxiety.  Perhaps the long-term outcome of the current crisis will be similar for Toyota.  And just as tire pressure sensors have been introduced, look for an engine kill feature to be marketed or mandated to respond to stakeholder demands created by the situation.

RE: Toyota uncontrolled throttle

I was hoping this would be the death of DBW, but clearly the legislative reflex of adding yet another layer of crap will prevail.

Yeah, I know how simple a kill switch can and should be; wait till the guvvamint gets through with it.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Toyota uncontrolled throttle

That's because this is what they think a "kill switch" does.
cannonauto

peace
Fe

RE: Toyota uncontrolled throttle

Just an idle thought. How many cases of SUA, or if you prefer, stuck throttles have been reported on manual trans cars that share components or software with the autos?

Incidentally this report is going for the jugular, but notice how the verbatims in the appendix (what the customer actually said) don't agree with the report that was entered into Toyota's warranty system. No wonder T wasn't taking them seriously. Unless that's what the service guys were told to do...


 

Cheers

Greg Locock


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RE: Toyota uncontrolled throttle

Interesting looking report Greg. I'll have to read that further later.

Funny though, I read the summary and it seems to be hinting that there is an electronic problem. Then, it says that brake to idle, which would be an electronic fix, may be the solution.
 

RE: Toyota uncontrolled throttle

(OP)
I've read in the paper, that in the event of an accident, the cops can forensically dump the memory of many car's ECU, get information like vehicle speed, braking, deceleration, ect. Anyone know if the suspect Toyotas are able to be inspected in such a manner?  

RE: Toyota uncontrolled throttle

Thanks Greg.  It took me a long time to read it.  One statement just jumps out..."...the blame the driver tack was immediate..."  something like that.

After reading the owner complaints, it is not hard to see that there is something more than a simple "shim" will fix.

Also, I found it odd that in the several occasions where the driver had the ability to select neutral, the engine simply over revved...apparently NO rev limiter.......???

I tried to simulate the unintended acceleration in the wife's Lincoln (with her protesting, I might add).  The engine rev limiter dropped the rpm to 3000/3500 immediately selecting neutral.  Also found that the ECM will not allow reverse at speed...good to know.  Oh well, I'm NOT in Toyota's demographic anyway!

Rod
 

RE: Toyota uncontrolled throttle

Reading some of the complaints is does sound like there is another issue.

I will say that I've had several issues with my C5 Vette accelerating while I was braking. Actually, it's more that it won't slow down even when I'm braking. When I depress the cluth during these events the engine revs up. However, I just move my right foot a little further to the left and the problem goes away...
 

RE: Toyota uncontrolled throttle

Good idea for you to stay clear of a Mini Cooper, Lionel.

Rod

RE: Toyota uncontrolled throttle

""I tried to simulate the unintended acceleration in the wife's Lincoln (with her protesting, I might add).  The engine rev limiter dropped the rpm to 3000/3500 immediately selecting neutral.  Also found that the ECM will not allow reverse at speed...good to know.""

The modern automatic shift system is actually quite refined. Most if not all auto shifters will go from drive to neutral by merely pushing the lever forward. You don't have to push the release button. Also the shifter will only go to neutral when you do this. It won't go to reverse unless you push the release button. Additionally most automatic shifters are mechanically connected to the trans  so the shift to neutral is mechanical enough that it will shift to neutral without electronics.

In addition there's no way you can damage a DBW system by overevving, all are limited at redline in gear and most have a lower limit, 3,000 to 4,000 when in neutral or park.

IOW these cars are designed to be easily and safely shifted to neutral, and that is the easiest safest thing to do with a stuck throttle. Why the media is spending so much time reporting Toyota's downfall and all the problems and not telling people what they need to do, with ANY car with a stuck throttle, is indicative of their ignorance and their "public service" is lacking.

The fact that people are dying in stuck throttle cars is also indicative of the poor level of driver education in this country. If you can breath you can get a license. If people were trained to shift to neutral nobody would have died.This is something that should be added to all drivers ed courses because with the added complexity of DBW technology there is greater chance of things going wrong.

It would be interesting to see an engineer from a specific discipline related to trans control and/or throttle control weigh in on this thread.   

RE: Toyota uncontrolled throttle

""Most if not all auto shifters will go from drive to neutral by merely pushing the lever forward. You don't have to push the release button. Also the shifter will only go to neutral when you do this. It won't go to reverse unless you push the release button.""

What this also means is you do not have to carefully "hunt" for neutral and worry if it's going into reverse or park, you merely slam the shifter forward in an emergency. It can only go to neutral if you don't push the release button.  

RE: Toyota uncontrolled throttle

Sorry Chris.  The wife's LS won't select neutral without pushing the little thingy....Then it quite easily goes all the way to reverse.  It did not, however, select reverse, only neutral and the revs dropped immediately to 3000/3500 !

One of the fatalities lately, the Lexus in San Diego, was driven by a CHP veteran and safety instructor...That suggests some level of advanced experience, does it not?

One instance at a local Toyota dealer indicated that neutral could not be selected.  ???  Another, the brakes failed to control the speed and the driver was able to "hold the off button" for the requires three seconds. A third driver selected neutral and the engine "revved uncontrollably" to the point of needing replacement from the dealer!  Go back and read  Greg Locock's post and inclusion, there are many more complaints filed with Toyota.

Many engineers posting here, including Mr.Locock, ARE experienced in the DBW and SBW systems in use today.

I don't think the "media" has gone overboard with this problem.  Quite the opposite, in fact.

Rod

RE: Toyota uncontrolled throttle

Back when I first heard the story about the runaway toyota's, I first thought it was like a sci-fi computer take over of the whole car, and the driver was locked out of all the input, such as turing the key off, flipping into neutral, stepping on the brakes. How far off could this be with nowadays computer integration into all operating aspects of the newer automobiles?  

RE: Toyota uncontrolled throttle

Ironically, who of us here would even think of designing an automated industrial machine without including a conveniently-placed E-stop button that works instantly.

 

RE: Toyota uncontrolled throttle

Quote (ChrisDuncan):

In addition there's no way you can damage a DBW system by overevving, all are limited at redline in gear and most have a lower limit, 3,000 to 4,000 when in neutral or park.
That assume an automatic, correct?  'Cause I guarantee I can mechanically overrev a manual...

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

""The wife's LS won't select neutral without pushing the little thingy....Then it quite easily goes all the way to reverse.""

then I should modify my statement to say, the Asian vehicles I'm familiar with go to neutral without the release and reverse only with the release. From a safety standpoint it seems to make sense.

I think the CHP veteran with the Lexus was a paddle shifter auto and he was possibly in manual mode which means neutral is over and up, not just up.

""That assume an automatic, correct?  'Cause I guarantee I can mechanically overrev a manual...""

Yes, and even with an auto it's probably going to go over one time, if it's floorboarded and put into neutral. But it's not going to stay there right?

RE: Toyota uncontrolled throttle

"I was hoping this would be the death of DBW, but clearly the legislative reflex of adding yet another layer of crap will prevail"

Luddite! Loom Smasher!
Out of interest whats your issue with DBW?
The cable operated throttle just does not fit in with modern EMS/Engine Hardware concepts and is grossly outdated on passenger vehicle engines.

From my point of view the problem is nothing to do with the actual engine management system per se but rather is a system integration issue.

By this I mean that the ECU was most likely doing exactly what was asked of it - which was exactly what the driver didnt want but the issue was the communication of thie wish ie the pedal mechanism. The issue laying with the pedal linkage sticking and keeping the throttle pot at some setting not desired by the driver.

MS

RE: Toyota uncontrolled throttle

It may well be that the ECU has no bugs, and does exactly what it's been told to do, based on what >it thinks it knows< about what's going on.

The 'system integration' issue is that, while they're much better than they used to be, the connectors and internal interconnects used in automotive systems are not yet up to our expectations.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Toyota uncontrolled throttle

Most markets require a red E-stop button on motorcycles placed in a standard location. MSF driver courses istruct turning off the engine using this 'kill' switch instead of the key precisely to get riders practiced with it's use and location.

As more newer MCs are including DBW throttles, one hopes the E-stop switches remain hard-wired rather than sending a meek 'cease & desist' to the ECU!

RE: Toyota uncontrolled throttle

I guess I'm "hard wired" <snicker> and, too old to change...

I was not aware the modern motorcycles were DBW, too.  Just as well I probably will never own another one after I sell my '48 Norton this summer.....The "kill" switch (sic) is the compression release!

Rod

RE: Toyota uncontrolled throttle

Yes, in addition to the 'drivers' for cars, MCs apparently benefit in FI modulation at part throttle with some form of electronic butterfly control.  Preliminary applications featured dual butterfly valve throttle bodies with one cable/driver actuated and the other ECU.  Now full DBW, mostly sports bikes so far, but no doubt will cascade.

RE: Toyota uncontrolled throttle

For those interested the David Gilbert preliminary report is available here at the attachment below.  In summary he was able to connect the two Hall outputs together with a resistor without the ECU noticing and then by connected one of those signal lines to the particular Vcc for the backup sensor he was able to get full accel.

It implies that two near shorts would have to occur.

RE: Toyota uncontrolled throttle

Yes you can shift to neutral, but, who is really commmanding the shift valves? You or the computer system?

When you turn off the ignition switch, who is commanding fuel and ignition off? You or the computer system?

When you push on the gas pedal who is commanding it? You or the computer system?  

When you push on the ABS brakes, who is commanding it?
You or the computer system?  

Some nice detailed information on the systems would be nice.

RE: Toyota uncontrolled throttle

One comment on dbw that I haven't noticed elsewhere:
Makes it super-easy to do cruise control- gets rid of the vacuum motor and controls. That has to be a nice part of the cost savings.
Regards
Jay

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: Toyota uncontrolled throttle

This is a far more serious problem than a lot of people may think. Just fixing the gas pedal linkage is not the complete answer. What happens when we have a similar problem with steer-by-wire?
There are two areas requiring additional discussion.
Surely there should have been high level behaviour boundary software present? Given the number and variety of accidents it is obviously there was not. ( I have worked on embedded sysems design).
Next why did not any of our departments of transport safety specialist catch this problem. They have known for years that software was going into cars. When new software is used for drive-by-wire, steer-by-wire or stability control then their is a public safety issue. Transport safety specialists MUST develope a capability to certify this software. They should have emulators/simulators that enable them to exercise in-boundary and out-of-boundary driving conditions.
As I said this is not just a Toyota problem. It is an early warning of major downstream problems unless changes are made now.

RE: Toyota uncontrolled throttle

a) steer by wire is currently illegal, and is 10-15 years away at least IMO

b)no electronic problem has been confirmed to date- most incidents have been pilot error, some have been mats. Very few are unexplained, those might be hardware/software related, we just don't know.

c)apparently your expertise allowed you to miss point b, ie your expertise is borderline irrelevant

d) They don't have that expertise. In most cases they don't even see a new car before it is launched. You would need to certify the system, not just the software. They don't have the emulators. They don't have the people. They don't have the cars. Apart from that they are all set. Would this certification process include the effect of jamming the pedal with aftermarket mats? or drivers pressing increasingly hard on the wrong pedal?

It is not a Toyota problem, it is a combination of operator error and the media enjoying a beatup, admittedly aided and abetted by an approach to PR that seems comically inept in retrospect.  

Cheers

Greg Locock


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RE: Toyota uncontrolled throttle

Hi Greg
Did not mean to imply it was a sortware problem, ie your point (b).
We can take advantage of the embedded software to read sensors. Lets say we do a dynamic read of speed, brake presure clutch position and gas pedal pressure, and compare the data to recent past data. From the results we can determine if a driver/car is/are exibiting signs of acceptable behaviour.
The point is with sensors, correctly located, and appropiate software I think we can increase the safety of the car by detecting some mechanical problems. It gives us a capability we never had with 'just mechanical contrivences'.
I think my experience is relevant. GM obviously thought so. I gave a talk to a boardroom full of their execs in Detroit. The topic, the future of computers in the automotive and appliance industries.

Thanks for your comment.

RE: Toyota uncontrolled throttle

Quote (thomasthebird):

The point is with sensors, correctly located, and appropiate software I think we can increase the safety of the car by detecting some mechanical problems. It gives us a capability we never had with 'just mechanical contrivences'.
Isn't that the current intention?  Appropriate sensors, appropriate software, etc.?  It's obviously not working as well as many had hoped, mostly because determining what's "appropriate" is partially a moving target and partially unknown or untestable.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Toyota uncontrolled throttle

The software attached to my feet, hands, middle ear and eyes tends to indicate to me how my mechanical systems are working, but yes, cars are getting safer for the average shmo.

I still resent that I cannot legally use a 6 point full harness because it is not self adjusting just because some other dopes do not adjust their belts correctly.  

Regards
Pat
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RE: Toyota uncontrolled throttle

If you mean there should be an override such that hitting the brake cancels the throttle signal, um yes, that does seem an obvious thing to do in retrospect and is already fitted to many cars.

It is not quite as simple as that, since simultaneous application of brake and throttle is a valid control state for some drivers in some conditions, and all drivers in one condition, unless they live in Holland.


 

Cheers

Greg Locock


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RE: Toyota uncontrolled throttle

Don't know about that Pat.  One of my best friends was Dutch.  His last name was Hill.

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

RE: Toyota uncontrolled throttle

Quote:

We can take advantage of the embedded software to read sensors. Lets say we do a dynamic read of speed, brake presure clutch position and gas pedal pressure, and compare the data to recent past data. From the results we can determine if a driver/car is/are exibiting signs of acceptable behaviour.

So, once this is implimented I'll have to use WOT on a regular basis or else the car will decide I'm making a mistake when I do try WOT and stop itself instead??

I think the media has just found a new, better story (BP).

But then, they're getting bored of that one too so hopefully something else fanciful but harmless will come along for them soon.
 

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