toyota electronic throttles vindicated by NHTSA

toyota electronic throttle vindicated by NHTSA

as someone with many years of experience with the development and validation of electronic control systems in automotive applications, this comes as no surprise to me. the depths of our robustness testing, failure mode effects analysis and subsequent mitigation efforts, etc, is astounding.

i predict two things will happen in this thread:

• ignorant will claim toyota = greatest in world and domestics suck.
• Dr Hess will claim toyota bought NASA after obama cut their funding

I personally think that the world would be well off by being quite cautious about buying Toyotas- since this brought out the fact that their cars, are indeed, boring. There are plenty off good choices out there, if you know what I mean.

(back at ya)

I always found Steve Wozniak's observations and experiences interesting on this subject. Just as interesting is the dismissal of his observations and experiences.

FT, what were Woz's observations/experiences?

Or they could just bring back the throttle cable and remove all doubt...

Javelin wrote: Or they could just bring back the throttle cable and remove all doubt...

Whoa, don't let your fancy-schmancy logic mess up a perfectly good corporate-government debacle. With a throttle cable, they couldn't impose new safety regulations for brake override to counteract the inevitable unintended acceleration! Simple, right? Sheesh, what's your problem?

Dr. Hess wrote: FT, what were Woz's observations/experiences?

That his Prius would start accelerating on its on when on cruise control. He could stop it by tapping his brake pedal.

That he could duplicate it through a sensor error (or two?), making it do it repeatedly and consistently.

That there were some coding errors in the software.

That he'd reported this to NHTSA and got ignored.

That he'd reported this to Toyota and at first got ignored, and then was meeting with them about it.

That he expected glitches and errors in systems and codes this complex.

That he would gladly buy another Prius or Toyota.

Javelin wrote: Or they could just bring back the throttle cable and remove all doubt...

If you go through the reliability numbers, cables are actually worse than electronic.

Somehow, people accept sticky cable throttles, but not the same on electronic throttes?

In reply to Javelin:

I suspect we share a love of mechanical linkages, but I've never had a drive-by-wire throttle stick. It has happened to me on cable operated cars, though. My E28 did it on hard left hand turns, as when you'd pull out into traffic from a driveway. Made for a few very, very exciting times. Also happened on a 2002tii I drove a few years ago.

I would agree Eric, that over the time span of the existence of automobiles, there have been more sticky cables than there were sticky electronicgizmowhoozeewhatsits. Seeing that fourhundredeightybazillion more cars have been produced since the invention of the mass produced auto (being built with cables) than the relatively few cars built after the invention of e-throttle, your data is skewed. If you can somehow come up with the percentage of cables that stuck versus the percentage of e-throttles that had errors, Id be interested in that statistic.

the next shirt that needs to be made is the save the cable shirt...

I had my '00 A6's throttle pedal get stuck on aftermarket floor mats. After the pedal was stuck to the floor boards, my knee jerk reach was to push the clutch in and take it out of gear. Then I watched it bounce of the rev limiter for what felt like forever, then I came to my senses and just tugged on the corner of the floor mat and dislodged the pedal. The ordeal seemed like it took minutes but was probably less than 5/10 seconds. Luckily I was merging on an empty high way.

Wozniak's observations seem quite plausible to me.

Software is complex.

One of my concerns is actually how these systems will react to 20 years of owners who DIY stereos and JC Whitney electrical accessories of who knows what kind, and of general wear and tear. I know the testing and analysis are staggeringly thorough, but it's simply not possible to exhaustively test everything a user may manage to do to a car. IMHO, the suggestion that it can't happen damages the credibility of the speaker. (Just in case someone jumps to any conclusions, I don't think AngryCorvair made any such assertion; just that the precautions taken are tremendous, which I wholeheartedly believe)

All that being said, it's not as though mechanical throttles are infallible. Stuck throttles aren't unheard of. They're not even that rare. I'd be lying if I said I didn't have some small worry about drive by wire, but I feel that it's a semi-irrational part of my brain, and that the risk is no greater than with normal throttles.

As an aside, another automotive website used the same findings by the feds to say that it had been proved that the incidents were hoaxes. Such sloppy use of the word 'proof' is part of the problem...

At least with a stuck throttle cable you know what is happening and have the means of stopping it, like turning the key off. I like most modern electronics, especially in cars (EFI and ABS come to mind, as well as electric-assist power steering pumps), but the actual human-machine interface should be all mechanical. When I stomp on the brake pedal, an actual piece of medal should move, thus stopping the car (unless all the fluid leaked out, at which point I could grab my manual handbrake and stop the car with mechanical force).

If you really want to get an idea of the types of losses "drive by wire" control produce, look into the aircraft industry. Even with redundancy and seperate systems there have been more computer-error crashes than hydraulic failures in older aircraft. The NTSB has some really interesting reading on the subject.

Oh, and I wish someone would actually listen to the Woz. If one of the premier code developers of the modern age says something is up, I'd damn well listen!

AngryCorvair wrote: ... the ignorant will claim toyota = greatest in world and domestics suck...

I actually see a lot more Toyota slamming than anything else. This entire event has been a great lesson in human nature, where it's clear that many made up their minds a long time ago and choose to ignore the findings, regardless what it is or who it comes from.

Substituting the word "Audi" for "Toyota", this thread is very similar to their cars decades ago... and there, too, people had "decided" that no matter what, Audi was guilty. And then, like now, some of the reports of failures were outright fraud, and the rest were people getting their foot on both the brake and gas.

It's the infamous "Prove you're not a witch" all over again.

alfadriver wrote:

Javelin wrote: Or they could just bring back the throttle cable and remove all doubt...

If you go through the reliability numbers, cables are actually worse than electronic. Somehow, people accept sticky cable throttles, but not the same on electronic throttes?

Because you could produce a feedback response to the problem. Nowadays, the driver is along for the ride. The modules do all the actual work.

I personally had the lack of feedback I get with DBW pedals. I like feeling the action of the cable moving against springs and linkage to tell me what is happening. The dead space in DBW pedals drives me nuts along with the absolute and discrete nature of them. But for the stupid simplicity of them, they are a god spend to the beancounting penny pinchers.

What I haven't seen mentioned anywhere is that much of this started as the economy tanked, making it harder to keep up the old car payment on the car they just bought....but stuff happens.

I have experienced stuck cruise control on a '70s 4-door Lincoln luxo boat trying to slow down to turn up the street I lived on. Touched the brakes--cruise was supposed to disengage--started turning, and just kept up the same speed. As I had already started the turn, there was lots of tire squealing, standing on the brake pedal, and hoping I didn't wind up on the corner guy's lawn. Made it with about a foot to spare, as it was a wide street, but, made me leary of cruise control for a long time. It never occured again.

4cylndrfury wrote: I would agree Eric, that over the time span of the existence of automobiles, there have been more sticky cables than there were sticky electronicgizmowhoozeewhatsits. Seeing that fourhundredeightybazillion more cars have been produced since the invention of the mass produced auto (being built with cables) than the relatively few cars built after the invention of e-throttle, your data is skewed. If you can somehow come up with the percentage of cables that stuck versus the percentage of e-throttles that had errors, Id be interested in that statistic. the next shirt that needs to be made is the save the cable shirt...

Nobody looks at pure numbers- it's all rates. The rates of cable throttle system failures is higher than ETC.

The data isn't skewed.

Javelin wrote: At least with a stuck throttle cable you know what is happening and have the means of stopping it, like turning the key off. I like most modern electronics, especially in cars (EFI and ABS come to mind, as well as electric-assist power steering pumps), but the actual human-machine interface should be all mechanical. When I stomp on the brake pedal, an actual piece of medal should move, thus stopping the car (unless all the fluid leaked out, at which point I could grab my manual handbrake and stop the car with mechanical force). If you *really* want to get an idea of the types of losses "drive by wire" control produce, look into the aircraft industry. Even with redundancy and seperate systems there have been more computer-error crashes than hydraulic failures in older aircraft. The NTSB has some really interesting reading on the subject.

As you can do with ETC.

Well, except with apparently Toyota.

for the "human interface"- the same thing can be said about a lot of technology. Yet we move on. Ever type on a real mechanical typerwriter? Or walk to the TV to change the channels on a knob? The question isn't about the interface, but is the new interface as reliable and fail safe as the old one.

Even with brakes- we did move on from cable brakes and drums. Seems to be ok once the technology was worked out. Unless you really want a hand pump for the fuel again. that's a human-mechanical interface. I know you said that EFI was ok- but where do you really draw the line?

Even now, we've gone from unassisted steering to fluid power assist to electronic power assist. Seems to work well. There may be a real connection, but it's not what people would expect, that's for sure.

I personally had the lack of feedback I get with DBW pedals. I like feeling the action of the cable moving against springs and linkage to tell me what is happening. The dead space in DBW pedals drives me nuts along with the absolute and discrete nature of them. But for the stupid simplicity of them, they are a god spend to the beancounting penny pinchers.

That's feel, though, not really feedback, isn't it? The feel of the cable doesn't tell you anything about the engine's response to your request. You could hook a cable up to a DBW throttle and just connect a spring to the end of it and have that. Given all the gritchy, sticky throttle cables I've dealt with, I'd be happy to be done with them.

I'm also uncertain that switching to DBW was the cheap option, given the relatively low cost of existing cable technology...

I do like the idea that DBW could allow relative ease in terms of running a large TB and still have very linear throttle response, though the fact is that I haven't ever driven a DBW car (unless that recent rental Cobalt was one...)

alfadriver wrote:

Javelin wrote: At least with a stuck throttle cable you know what is happening and have the means of stopping it, like turning the key off. I like most modern electronics, especially in cars (EFI and ABS come to mind, as well as electric-assist power steering pumps), but the actual human-machine interface should be all mechanical. When I stomp on the brake pedal, an actual piece of medal should move, thus stopping the car (unless all the fluid leaked out, at which point I could grab my manual handbrake and stop the car with mechanical force). If you *really* want to get an idea of the types of losses "drive by wire" control produce, look into the aircraft industry. Even with redundancy and seperate systems there have been more computer-error crashes than hydraulic failures in older aircraft. The NTSB has some really interesting reading on the subject.

As you can do with ETC. Well, except with apparently Toyota. for the "human interface"- the same thing can be said about a lot of technology. Yet we move on. Ever type on a real mechanical typerwriter? Or walk to the TV to change the channels on a knob? The question isn't about the interface, but is the new interface as reliable and fail safe as the old one. Even with brakes- we did move on from cable brakes and drums. Seems to be ok once the technology was worked out. Unless you really want a hand pump for the fuel again. that's a human-mechanical interface. I know you said that EFI was ok- but where do you really draw the line? Even now, we've gone from unassisted steering to fluid power assist to electronic power assist. Seems to work well. There may be a real connection, but it's not what people would expect, that's for sure.

You're skewing my words. If you notice, I don't have any problems with technology assisting my inputs (such as power steering), my problem is when the technology has replaced my inputs with their own. It's like the manual trans versus auto trans discussion. When I stick a gearbox in 2nd gear on an autocross course, it stays in 2nd until I change it. In an auto, I can select 2nd and even on the "auto manuals" it will probably decide to upshift or downshift without my input, which pisses me off.

The electronic throttle is the same thing, I'm inputing a certain amount of throttle and it's giving me less for fuel economy BS. Or deciding to whatever it wants in it's range of motion instead of precisely where I want it. Combine that idiocy with the push-button start/no key and an auto trans and it's a recipe for disaster.

If you ask me, all cars should be required to have a cable pedal with return spring, a key that will shut off the engine, a manually activated hand brake that mechanically brakes the car (I swear I will knock the daylights out of the idiot that invented automatic electronic parking brakes), and a transmission that will actually shift to neutral and stay there. Also, steering columns should always mechanically be connected to the wheels (I know Mercedes has a model where the steering wheel only turns electrons, which scares the crap out of me), and so should brakes (hydraulicly, I understand the fluid could come out, see mechanical emergency brake above).

THOSE are human-machine interfaces that matter.

In reply to ransom:

To me, feel is feedback. When I push down the pedal to move my vehicle, I feel what the engine is doing through the cable. Plus the effort to push that pedal is different, DBW pedals are WAY lighter in effort. There is a complete disconnect from what the DBW pedal provides me in information as to what the engine is doing for me. I need a scan tool and use my other senses to see and feel what the engine is doing which takes me away from my duty to DRIVE, IMO.

DBW is cheaper as you have eliminated the IAC and associatied wiring, the cable, and you already have excess computing power inside the PCM. Also now you can place that throttle body anywhere and on anything without having to "engineer" a cable, IAC to match. That eliminates excess part numbers to carry and supply. Wire is cheap, cables are not.

And your rental Cobalt should have been DBW.

The only reason a DBW pedal is lighter effort is because of a design decision. They have springs on them. Want more weight? Bigger spring.

I've got some cars with wires and some cars with cables. But I'd have to think about it to figure out which was which - and once in a while I get surprised. I can't say I've ever felt there was a lack of feedback. The only time I notice is when I'm running cruise control and the throttle pedal doesn't move on its own. Heck, we've run Elvis (our LSx-powered Miata) both ways and I never noticed a difference.

In reply to Javelin: Yes, I am twisting your words- it's all sematics, and many of your "interfaces" are pretty arbitrary. Especially since you don't seem to know what the failure mode really feels like.

The ETC does assist with your input- you assume that it's some kind of fuel economy BS, and it typically is quite the opposite, so that perormance feel is better than expected.

As I've said, cables are less reliable, and fail more than ETC's (on a rate basis), so why you'd have those is beyond me. They will fail more often. They key is also debateable, the point is to be able to turn the car off- a properly designed button will do that.

The trans- well, that's very customer dependant, and it appears that most customers don't really want direct connection. But that's just reading the market for autos over manuals.

But your "recipe for disaster" isn't about how the thechnologies interact with each other, it's about how a company chooses to make them interact- and it appears that problems that are precieved by Company T's issues are not always real. Had the choice been- if throttle sticks, then IF trans moves- allow disengagement, and IF brakes are applied- override throtte, and IF button is pushed, turn off car. Not choosing that path doesn't make the technology bad, it makes the implementation bad.

For the brakes- what if you crack a hose? There are a number of failure modes that hydralics have that electrics would be very different to. The assumption that one is better than the other is more about familiarity than going through the very tough process of understanding every tiny piece, and how they can fail and add up all of the failure rates. You can pretend that there's a major feel element to hydraulics, but most assist systems dampen that out so much that it's quite easy to replicate. The fluid coupling you seem to like can be interrupted just as easily as an electric coupling.

The question is: Pile of mechanical compents vs. pile of electrical components- identify all the parts, how they fail, what happens when they do fail, and how often they fail- who wins?

the difference between assist and replace is a very fine line.

I love DBW, but it took a little getting used to. Otherwise, I think it also allowed flexibility to the designers as to where and how to mount the pedal. On my current car, its hinged at the floor. Effort is light, but constant throughout the range of motion.

I find someone's ability to get "feedback" on a car's performance through a cable to be a bit suspect; almost like the feedback that your car feels faster after it's been washed.