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  1. #1

    Prius probed for engine stalls

    SAN FRANCISCO (MarketWatch) June 1, 2005

    Federal regulators on Wednesday officially opened an investigation into the red-hot Toyota Prius, responding to complaints alleging the cars' hybrid engine cuts out in traffic.

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  3. #2

    Prius probed for engine stalls

    I can see how the stalling issue could become a problem, but not just with the Prius. Most new cars are run by computer control and monitoring systems. It's just that the Prius has an especially complex computer to control both the gas and the electric portions of the engine (along with other things like the transmission). If something goes even the slightest bit whacky in that control system, I could see how the entire engine might just shut off. Of course, turning the engine off is not the best way to deal with a computer 'crash'. If anything, it should just revert to a 'manual' mode that at least lets you get the car safely off the road.

    In fact, I also have a '95 Isuzu Rodeo and this stalling thing nearly happened to me while cruising at 65 on the highway. According to the mechanic at Isuzu, in the Rodeo, the transmission system is tied directly into a computer control system. If that system determines that the transmission is malfunctioning, the entire system can shut down (stalling the engine). The stall appeared to happen during a shifting operation (automatic transmission) between two different gears. This happened right after I had had the Rodeo serviced (they had to take the transmission off during the service). So, pretty much any computer controlled car can have this 'stalling' issue and it doesn't appear limited to just the Prius. It all depends on how the computer control engineer(s) decide to deal with unexpected situations within the control software.

    As more and more cars become equipped with complex computer control systems as standard, I'd expect to see this issue become more common across the board. Frankly, however, I'd prefer that the computer control system designers put a 'manual' mode on the vehicle to allow the driver to override the computer control system if a software glitch is preventing the system from operating properly (vs an actual engine or mechanical problem). The designers should give the driver some in-dash computer diagnostic tests (now that many vehicles come equipped with graphical displays) to run before determining whether or not to use manual mode.

  4. #3

    Prius probed for engine stalls

    Now that you put it that way.

    My wife used to work at a GM dealership and I remember incidents like that when computer controlled gas engines first started appearing 10 years ago.

    The one thing that came to mind when I first heard about this is 'What protections does the programming in a hybrid have from a two footed driver?' If a driver is continuously pushing the gas and the brake at the same time with the increased complexity in a hybrid, what would it do?

    I'm sure the engineer's thought of this and this kind of driving probably only reduces the life of all the components like in a standard vehicle!

  5. #4

    Prius probed for engine stalls

    Is stalling at highway speeds an acceptable risk?

  6. #5

    Prius probed for engine stalls

    >Is stalling at highway speeds an acceptable risk?

    Not especially. But, as cars come equipped with more and more sophisticated computers, the chance for a computer crash increases. When the software crashes, the software/hardware designer has to make a choice what to do with the vehicle in operation. So far, it appears they choose to stall the engine (or perhaps there's a synergy between the computer control and the engine and when that interface is broken, that's a side effect from the engine itself). As with any application, there's always the possibility of a completely unexpected error. Again, the designers have make a choice on what to do.

    This is why I suggested a manual override switch or some other mechanism to allow the driver to continue driving the vehicle for at least 5-10 minutes (enough to get the car off the road). Obviously, if there's a mechanical problem (i.e., you throw a rod), then there's little you can do.

    There's always a chance of stalling at highway speeds simply from mechanical problems alone. It's just that it appears some people are less tolerant of computer crashes/glitching when the mechanical portions of the car are functioning properly.

  7. #6

    Prius probed for engine stalls

    >the chance for a computer crash increases

    Does anybody what computer language the Prius uses? Maybe Toyota got a bargain on old Windows 95 program disks from MicroSoft! Maybe the Prius drivers hit CTRL+ALT+DELETE while on the freeway!

  8. #7

    Prius probed for engine stalls

    This issue is a kind of 'so what' thing in the context of modern engine controls. One of the questions I get is 'how are you going to work on it?' When you change the chip on a gas engine for more performance or find out a $300 computer card controls your ignition and there is no distributor cap to be found ... there is a reason my auto mechanic father-in-law decided the grease rack and towing would occupy him in his semi-retirement.

    I think I read there are 20+ microchips in a standard gas engine vehicle and about twice that in a hybrid which has the chip manufacturers rubbing their hands.

    Its the future and just hope you don't drive through a strong EMP!

  9. #8

    Prius probed for engine stalls

    I thought I'd add another one since reading in Walter McManus's column that an injury lawyer is already fishing the Prius stall cases.

    When my 1983, originally brown, 4x4 S10 pickup was flat black and 11 years old with a couple of dents .... I was driving down the highway about 50 mph on black ice when the engine suddenly stalled locking the wheels, I spun around a couple of times and went into the 3 feet of snow in the ditch ... after regaining composure I turned the key, started the engine, put it in 4 wheel drive and drove out the ditch and off down the road again. (Note that this is a highway full of log trucks and low boys with heavy equipment and other things you don't want to get in front of). I soon upgraded to another vehicle.

    Like I mentioned before these types of incidents happen in other vehicles too. I think the first one that caught my attention was in the early 90's and the problem was a bad 'card' and to change out the 'module' and this was in a new full size pickup.

    Not trying to say this isn't serious and that I'm not concerned about my 6 week old Prius, but then again the incident rate is low and I haven't had any problems. I have to admit 'drive by wire' takes some adjustment though and it's coming to more vehicles than just the Prius or just hybrids.

    There are actually a couple of cases in the list linked by Walter McManus on his blog, but then again this is the first such list like this I've read. Maybe I should look up a complaint list for a standard reliable vehicle .... nah.

    I guess that goes to show you the double edged sword of hyping hybrids ... something goes wrong or is percieved to go wrong with the 'Gee Whiz' stuff and the media picks up on it and gets 1+2=16 almost immediately.

  10. #9

    Prius probed for engine stalls

    Before computers, the 'fabulous' GM Vega quit on
    the freeway at 65 mph suddenly!
    Dealer did a major tune up which did not help.
    Following wires curiously revealed a third one
    from the oil pressure sensor, not to the gauge
    but to the gas tank! Located in the tank was an
    electric fuel pump. Reasoning said that this was
    an attempt to shut down the engine [if you could call it that] in case the oil pressure dropped, thereby protecting the manufacturer from being
    accused of putting junk in the hands of consumers.
    Changing out the engine oil to 60 weight solved
    the problem until a trade was possible. Still, the
    dealer never had a clue!!

  11. #10

    Prius probed for engine stalls

    Craig Van Batenburg is an independent master hybrid technician. He suspects user error. See his possible explanations:


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