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A Car With A Mind Of Its Own
mindriot writes "When Hicham Dequiedt, driving on a highway between Vierzon and Riom in central France in his Renault Vel Satis this Sunday, was overtaking a truck, his car began accelerating to 120 mph on its own, apparently due to a defect in the cruise control system. Stomping on the brakes proved pointless and, having a magnetic card for a car key, he could not cut the ignition. After calling the police from his cell phone who then attempted to clear the streets of any danger to him, in what he described as the most fearful event of his life, he raced down the highway for another hour before finally managing to stop the car. Read about the incident here or, in more detail, in this article by the German 'Spiegel' (translation). The case is still under investigation. Are we putting too much trust in the increasing number of electronic systems that our lives depend upon?"
If this ever happens to you do not ever attempt to turn the ignition all the way off... In most cases you will lose both your power steering and your power braking. Make sure that you keep it at least on partially as most cars will not lose total power this way.
If you are traveling at a high rate of speed losing power steering/braking will cause more problems for you. First try neutral and even a lower gear if for some reason neutral isn't engaging. It's going to over-rev the engine but personally I'd prefer to replace a transmission or the entire engine rather than my blood or organs.
I couldn't read the translated article as it just wasn't working so I don't know if this was suggested or not but if it wasn't suggested by the police I just can't understand why not.
Emergency brakes no longer exist. They are called parking brakes now, because they aren't designed to resist the torque of the engine, they just have enough power to hold the car from rolling, and even then, cars with manual transmissions are recommended to be put in either reverse or first gear to give additional resistance to keep from rolling.
The "emergency brake" is really just a parking break or "hill holding break" (designed to hold a car on a hill while engaging a manual transmission). Generally, enough force cannot be applied by the "emrgency brakes" to slow down a rapidly moving car without significant stopping distance. The "emergency break" also has the added disadvantage of ususally being attached to only two wheel breaks. Because of this, when applied at higher speeds, they tend to spin the car (usful for sheading speed only if you are an expert and have the road clearence - also usefull for "cool bootlegger moves").
Ever try to stop a car with them? Ain't gonna happen. They're rear wheel only, and even if you do manage to put them on hard (requires a LOT of force), you'll just lose control of the vehicle.
Once, when I was about eight years old, I was in the car with my grandma when the brakes went out. She didn't know what to do. I said "shift down" (automatic transmission) - she did, and we coasted to a stop shortly thereafter.
It's amazing to me that this guy had the presence of mind to call on a phone, but for an HOUR didn't think of downshifting.
Probably he, like most other drivers, is only concerned about going FASTER, not slower.
Most every car made since the mid eighties has an electronic rev limiter on it. Attempt to rev past this limit, and the ECU will selectively cut fuel/spark to keep the engine speed under control.
;)
It's very accurate; +/- 20 RPM typically.
Sticking an engine with a stuck throttle into neutral will result in it banging off the limiter and making a lot of noise, but it won't overrev.
You can, however, MECHANICALLY overrev a manual transmission by downshifting into a lower gear while the wheels are turning at a faster speed than is otherwise proper for that gear. The wheels and the engine are mechanically connected, and downshifting to too low a gear will spin the motor up - no rev limiter can protect against this.
In certain BMW M3s, the transmission mounts get a little sloppy, and engine torque reaction under hard acceleration can rotate the transmission enough to move the shift gates. It's possible then to try and go 2->3 or 3->4, and hit 1 or 2 instead. This is invariably fatal to the motor. You will bring your pistons home in a bucket.
Depending on the contstruction of any given automatic transmission, it may or may not allow you to take it out of gear and go into neutral under throttle. If you are silly enough to be driving an automatic, this could be a problem - but anybody who'd buy an auto trans where a manual was availible would steal sheep - so you probably had it coming.
DG
Want to learn about race cars? Read my Book
Uhmmmmmmmm ... no.
Unless you have one of the (few) cars with electrical power steering, you certainly will not lose power steering by shutting of the ignition.
So long as the engine is turning, the entirely mechanical power steering pump will continue to rotate and provide pressure to the system.
So long as the engine is generating manifold vacuum, you will have power brake boost. Beyond that, some cars (I know my old Volvo had one) have a diaphragm vacuum pump in addition to manifold vacuum to power the brake booster.
The only danger in killing ignition is in carburated autos, where you will continue to run fuel through the engine without spark. This will destroy any catalytic converter, and has a good chance of causing numerous backfires, and damaging the remainder of the exhaust system.
In the same Volvo wagon with the vacuum pump, it had a major overheating problem, but with its fuel-injected engine, killing ignition was a non-issue. No electricity, no fuel pump, no backfire. After climbing a long grade and getting up to 130, cresting the hill, and killing the ignition would cool it back down in just a few tens of seconds just from pumping all that relatively cold air through the engine. (Of course, shock cooling the engine was probably worse for it than the overheating, but it was a dispos-a-car anyway.)
How does the Slashdot Effect happen given that no slashdotters ever RTFA?
1999-06-10 http://news.bbc.co.uk/1/hi/uk/365915.stm
1999-06-08 http://news.bbc.co.uk/1/hi/uk/364260.stm
1999-06-07 http://news.bbc.co.uk/1/hi/uk/363407.stm
1998-10-21 http://news.bbc.co.uk/1/hi/uk/197964.stm
The German language article says he came to a stop about 20km before a toll booth...
On the same theme: Saturn made a interesting assumption about their cars a few years ago. At high speed they reduced gas to the engine to control the speed to a maximum of 105mph. According to this entry in Risks digest (source of endless scary stories about computing and automation risks) the author was left going down hill at over 105mph, coasting, with a stalled engine, no power brakes and no power steering.
... not fun at all...
Audi had a problem years ago that was supposedly due to a programming error. At low RPM the computer would increase power but fail to sense it under some circumstances. Net result: your car would suddenly go foot to the floor while you were stopped at a red light.
The driver called police to say the cruise control of his Renault Vel Satis had jammed while overtaking a lorry, and that all attempts to brake or put the automatic into neutral had failed, police said Tuesday.
According to another article, Renault's ceo said that on first examination on the premises, they noticed no particular marks on the brake disks and on the brake pads.
If it's true, it's fishy indeed.
They also say that the car seemed to behave normally when a mechanic drove it from his truck to a garage, but if it was some kind of rare sftware malfunction and the computer reset itself, they wouldn't notice anything anyway.
I don't even know if they have logs in these car computers.
1. I do not find it hard to believe. Vel Satis is fully electronic automatic transmission with keyless entry and ignition. You cannot switch to neutral if the computer is bust. You cannot turn off the engine either. And if it has already been allowed to accelerate to 120mph the handbrake (dunno if it even has one) and the breaks will not do shit.
2. It is what you get from integrating non-vital and vital circuits to save costs. Dunno if the Vel Satis uses similar electronics, but the recent Citroen and Peugeot (the other two french makes) run using a single integrated on-board computer that controls everything from wipers to engine. To add insult to injury it is a low end crap running Windows CE. It is quite noticeable - their speed displays are fully digital and it takes them 2+ seconds to update between reading (as of Citroen C2). Enough to lose your license in some of the UK speed camera happy areas. That is besides that it is an el-cheapo passive LCD which cannot be read if you have polaroid sunglasses or if the sun is behind you (Citroen C2 and C3 at least).
3. This case is an example why you should not buy an automatic and a keyless entry until proper cars are available. In fact I would rather have my speedo analogue as well (it takes less time for human brain to read an analogue dial compared to a digital number).
Baker's Law: Misery no longer loves company. Nowadays it insists on it
http://www.sigsegv.cx/
The first article is on point... it says average cars' brakes have 3-5 times more horsepower than their engines.
Here is an article which specifically talks about the Audi problems...
Most car experts and magazines such as Car and Driver supported Audi's position, knowing full well that working brakes can always overpower the engine, even at full throttle. But major media outlets chose to ignore basic facts and instead gave front-page treatment to theories about sunspots causing cars to run wild.
Nothing to see here; Move along.
In all the cars I've ever owned/seen, the hand brake cable is connected to the exact same rear brake pads as the foot brake is connected to. If the pads wear out, the solid metal behind the pads comes in contact with the drum/disk and they overheat. But there's no wire in contact with tire outcome.