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Comment by thechao | Hacker News Reader

Toyota never had an “unintended acceleration issue”—that was purely human error. A Toyota engine can’t overpower its brakes, unless there was gross negligence in the care of the brakes, i.e., they were totally inoperative. Just to make sure we’re clear on the braking thing: if you were to accelerate a Toyota sedan (any of them) to 70mph, then stomp on the brakes while holding the accelerator to the floor, the car will absolutely come to a complete halt in about the same distance as if you didn’t have your foot on the accelerator. Here’s another thing to back up my claim: how do you think burn outs work?

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While you're right that the engine will not overpower mechanical braking, I think the bigger problem is that modern hybrid and electric cars have been moving to brake-by-wire so that they can balance mechanical braking with energy recovery.

The result of Toyota's firmware audits were terrifying [1], and I think it's still reasonable to be concerned about potential issues here. If the brake-by-wire system were to have firmware issues, your point would be moot.

The thought that Boeing probably needs a similar audit to shine light on some dark corners and encourage them to clean up their act also seems quite reasonable.

[1] https://users.ece.cmu.edu/~koopman/pubs/koopman14_toyota_ua_...

I thought the problem with braking to overcome a runaway engine was that people don’t commit to it. If you brake hard to a stop then it will work, just like you say. But if you brake some and try to figure out what’s wrong and brake some more and let up and fiddle with the accelerator and brake a bit more and on and off like that, you’ll overheat them to the point that they won’t be able to overcome the engine anymore.

an "unintended acceleration issue" is quite orthogonal to whether the brakes work perfectly and could overcome the engine.

No, that was never proven, and as another poster pointed out, the independent audit of Toyota's practices suggests that random and uncharacterized faults in Toyota's ECUs cannot be ruled out as causes for the unintended acceleration episodes.

As another sign of this, Toyota both stonewalled the investigation and later fired the director of the division in charge of ECU engineering, and rebuilt the division.

>the independent audit of Toyota's practices suggests that random and uncharacterized faults in Toyota's ECUs cannot be ruled out as causes for the unintended acceleration episodes.

>cannot be ruled out

That seems like a very weak statement. If you asked a software auditing firm to inspect your massive codebase they're not going to "rule out" any bugs either.

Have you read the independent report? The point of the report was that their engineering practices (both software and hardware) were so extraordinarily dangerous, the ECU was impossible to test with any authority. Its behavior was effectively non-deterministic in many of their cars from that era.

That's sort of the point. I'm not defending their code. I'm pointing out that even if the code were immaculate, it would be hard for an code auditing firm to say "this has no sudden acceleration bugs". It's a very CYA statement.

I do not know why you are getting the downvotes, but you are correct. The DoT and independent inspectors backed up this scenario.

https://www.caranddriver.com/features/a15125313/its-all-your...

This doesn't mention the horrible spaghetti code NASA found when reviewing the code. 250k lines of C with thousands of global variables. It leaves a pretty bad taste.

Then again, I still wouldn't be surprised if most people were just too perplexed if their car suddenly accelerated like crazy and not stay calm and hit the brakes as hard as possible right away. It might take you a second or two to get what's going on, and by then you might already have lost control.

I can't speak to what most people would do, but I've experienced unintended acceleration before. The throttle stuck all the way open while I was driving a friend's car because he routed the throttle cable improperly after installing a larger carburetor for more power. I had intended to give it full throttle, but only briefly.

I stood on the brakes and didn't let up. He reached over and shut off the key, which locked the steering and put us in the ditch, but at relatively low speed due to the continuous braking.

Doesn't the steering column only lock when you remove the key?

No, and I haven't driven a car with that behavior. Most US market cars have a sequence of lock, off, accessory power, on, start as the key is turned farther clockwise. Some cars require manipulation of a lever near the key to reach the lock position.

Very new cars with an entirely radio-based "key" might behave something like that.

>Then again, I still wouldn't be surprised if most people were just too perplexed if their car suddenly accelerated like crazy and not stay calm and hit the brakes as hard as possible right away. It might take you a second or two to get what's going on, and by then you might already have lost control.

Without electronics or software involved, many years ago (1980's or so) there was a FIAT diesel engine, that was widely used on mid-sized cars, typically the Ritmo (Strada in the US) that had a servo-brake working by depression coming from the engine that had a defective membrane.

Basically, it could happen that the membrane broke/got a hole in it and the oil from the engine would enter the combustion chamber, to the effect that the engine would go up at full revs.

And you couldn't switch it off, the only way was to depress the clutch pedal, put in fourth or fifth gear and brake hard while releasing quickly the clutch.

It was a terrifying experience for someone not very familiar with cars/engines, though most people using a manual gearbox know that by depressing the clutch and braking would stop the car (so no or few accidents caused by this issue), knowing how to forcibly turn off the engine wasn't (and still is not) common knowledge, the motor would continue going on for a few minutes until something else would break or the oil in the engine would have been mostly burned (leaving the engine with no lubrication at full revs) until the engine would seize up.

I agree with your first statement that it's clearly human error but I disagree with the argument about burn outs. Static friction is an entirely different mechanism than kinetic friction. The force needed to stop the car in your first scenario is kinetic friction. Burn outs work by static friction. In general, static friction is the higher of the two.

if you were to accelerate a Toyota sedan (any of them) to 70mph, then stomp on the brakes while holding the accelerator to the floor, the car will absolutely come to a complete halt in about the same distance as if you didn’t have your foot on the accelerator.

Are you saying the additional, let’s say, what?, 60kW of power being applied to the wheels will require no additional effort at the brake pedal to overcome.

Colour me unconvinced.

I’ve never tried to imitate a burnout at 70mph / I’m not convinced the circumstances are the same.

Assuming a properly-maintained braking system, it makes very little difference.

>And despite dramatic horsepower increases since C/D’s 1987 unintended-acceleration test of an Audi 5000, brakes by and large can still overpower and rein in an engine roaring under full throttle. With the Camry’s throttle pinned while going 70 mph, the brakes easily overcame all 268 horsepower straining against them and stopped the car in 190 feet—that’s a foot shorter than the performance of a Ford Taurus without any gas-pedal problems and just 16 feet longer than with the Camry’s throttle closed.

From https://www.caranddriver.com/features/a16576573/how-to-deal-...

Hmmm, interesting. Colour me convinced.

That sounds like a fun experiment to try on, say, a winding mountain road...

I wonder if people making this comparison will appreciate the irony if someday it proves that the same situation applies here (I.e. user error).

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