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#71
January 24th 05, 11:22 PM
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Steve wrote:
> Matt Whiting wrote: > >> Alex Rodriguez wrote: >> >>> In article .com>, >>> says... >>> >>>> Our 2002 Sebring Coupe with 6cyl- 3.0 engine suddenly accelerated while >>>> backing up in a parking lot causing a wreck. It lurched backward at top >>>> speed. Has anyone heard of this happening? >>> >>> > > I firmly believe that virtually 100% of the cases of "unintended > acceleration" in cars made prior to about 2001 were because of driver > error. There's simply NO way that an engine with a mechanical throttle > linkage can accelerate unless the return spring breaks, and it doesn't > "go back to normal" immediately thereafter- it stays broken. > > Howver, in recent years more cars are being built with "throttle by > wire" in which a computer-controlled servo moves the throttle blades, > not a direct mechanical linkage to the accelerator pedal. I know that > the systems and software go through tremendous testing, but I no longer > feel confident in saying that it "cannot happen" anymore. Yes, that is true. Even cars with a mechanical POSSIBLY could do this if they have cruise control as it can also control the throttle. However, as has been pointed out already, it would take several simultaneously component failures for this to happen. Not impossible, but certainly highly improbable. I don't know anything about the design of drive-by-wire systems, but fly-by-wire airplanes have thus far proven as safe as their predecessors with mechanical controls. As a former software engineer, however, I admit to being more nervous on a fly-by-wire airplane than on a conventionally controlled one. :-) Matt 
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#72
January 24th 05, 11:22 PM
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James C. Reeves wrote:
> "Steve" > wrote in message > ... > >>I firmly believe that virtually 100% of the cases of "unintended >>acceleration" in cars made prior to about 2001 were because of driver >>error. There's simply NO way that an engine with a mechanical throttle >>linkage can accelerate unless the return spring breaks, and it doesn't "go >>back to normal" immediately thereafter- it stays broken. >> >>Howver, in recent years more cars are being built with "throttle by wire" >>in which a computer-controlled servo moves the throttle blades, not a >>direct mechanical linkage to the accelerator pedal. I know that the >>systems and software go through tremendous testing, but I no longer feel >>confident in saying that it "cannot happen" anymore. >> > > > Which begs the question...why make a very simple and reliable system more > complicated (with all the associated problems that more complicated systems > have)? Saves weight and can allow even more automatic control of the engine. Matt
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#73
January 24th 05, 11:25 PM
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Steve wrote:
> maxpower wrote: > >> "James C. Reeves" > wrote in message >> ... >> >>> "Steve" > wrote in message >>> ... >>> >>>> I firmly believe that virtually 100% of the cases of "unintended >>>> acceleration" in cars made prior to about 2001 were because of driver >>>> error. There's simply NO way that an engine with a mechanical throttle >>>> linkage can accelerate unless the return spring breaks, and it doesn't >> >> >> "go >> >>>> back to normal" immediately thereafter- it stays broken. >>>> >>>> Howver, in recent years more cars are being built with "throttle by >> >> >> wire" >> >>>> in which a computer-controlled servo moves the throttle blades, not a >>>> direct mechanical linkage to the accelerator pedal. I know that the >>>> systems and software go through tremendous testing, but I no longer >>>> feel >>>> confident in saying that it "cannot happen" anymore. >>>> >>> >>> Which begs the question...why make a very simple and reliable system >>> more >>> complicated (with all the associated problems that more complicated >> >> >> systems >> >>> have)? >>> >>> ITS ALL ABOUT MONEY, no cables, brackets, save on money > > > > Yep- the throttle body location can be anywhere and you still use the > same accelerator pedal and the same throttle servo. No custom cable > lengths. > >> and supposed to be a faster response for acceleration > > > And the sick and twisted irony is that "throttle by wire" engines are > NOTORIOUS for having a sluggish throttle response compared to direct > cables. The software always optimizes the throttle opening rate to > minimize fuel consumption and emissions, rather than letting you bang > the butterflies open instantly the way you can when your right foot is > firmly cabled to the throttle blades. That is the NUMBER ONE gripe I > hear from Ram truck owners who have compared the new 5.7 Hemi to the old > 5.9 360. Yes, the Hemi has more horsepower and torque, but the old 5.9 > slams you back harder and quicker when you first punch it because it > responds instantly. I've also observed the same thing when comparing an > older cable-throttle 3.5L v6 to the newest throttle-by-wire 3.5L v6. The fuel injection on current mechanically operated throttle bodies is controlled by the computer. I don't see how controlling the butterfly is inherently any slower than controlling the fuel. And you need both fuel and air to get the engine to respond. Matt
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#74
January 25th 05, 07:20 AM
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>WRT spark plugs, you are actually claiming that if I install
> Autolite, NGK, AC Delco or some brand other than Champion spark > plugs in a 1985 ChryCo vehicle with a turbo charger, start the > engine, disconnect the coolant sensor and check the ignition > timing with a stroboscopic timing light, I'll see different > timing setting between the different brands of spark plugs? >Idle on those vehicles were controlled by >timing Well, that throws away my theory that the AIS actuator had anything to do with idle control... Toyota MDT n MO
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#75
January 25th 05, 07:38 AM
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maxpower cut and pasted:
>WRT spark plugs, you are actually claiming that if I install > Autolite, NGK, AC Delco or some brand other than Champion spark > plugs in a 1985 ChryCo vehicle with a turbo charger, start the > engine, disconnect the coolant sensor and check the ignition > timing with a stroboscopic timing light, I'll see different > timing setting between the different brands of spark plugs? maxpower replied: >Idle on those vehicles were controlled by >timing Well, that throws away my theory that the AIS actuator had anything to do with idle control... Toyota MDT in MO
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#76
January 25th 05, 11:25 AM
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Good point; I too have had the accelerator pedal become held down
after flooring it due to a displaced/crumpled floormat. I bet many people have experienced this at one time or another. It is noteworthy, however, that the cause of the problem in this case is usually very obvious after it happened.
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#77
January 25th 05, 03:25 PM
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Matt Whiting wrote:
> Steve wrote: > >> maxpower wrote: >> >>> "James C. Reeves" > wrote in message >>> ... >>> >>>> "Steve" > wrote in message >>>> ... >>>> >>>>> I firmly believe that virtually 100% of the cases of "unintended >>>>> acceleration" in cars made prior to about 2001 were because of driver >>>>> error. There's simply NO way that an engine with a mechanical throttle >>>>> linkage can accelerate unless the return spring breaks, and it doesn't >>> >>> >>> >>> "go >>> >>>>> back to normal" immediately thereafter- it stays broken. >>>>> >>>>> Howver, in recent years more cars are being built with "throttle by >>> >>> >>> >>> wire" >>> >>>>> in which a computer-controlled servo moves the throttle blades, not a >>>>> direct mechanical linkage to the accelerator pedal. I know that the >>>>> systems and software go through tremendous testing, but I no longer >>>>> feel >>>>> confident in saying that it "cannot happen" anymore. >>>>> >>>> >>>> Which begs the question...why make a very simple and reliable system >>>> more >>>> complicated (with all the associated problems that more complicated >>> >>> >>> >>> systems >>> >>>> have)? >>>> >>>> ITS ALL ABOUT MONEY, no cables, brackets, save on money >> >> >> >> >> Yep- the throttle body location can be anywhere and you still use the >> same accelerator pedal and the same throttle servo. No custom cable >> lengths. >> >>> and supposed to be a faster response for acceleration >> >> >> >> And the sick and twisted irony is that "throttle by wire" engines are >> NOTORIOUS for having a sluggish throttle response compared to direct >> cables. The software always optimizes the throttle opening rate to >> minimize fuel consumption and emissions, rather than letting you bang >> the butterflies open instantly the way you can when your right foot is >> firmly cabled to the throttle blades. That is the NUMBER ONE gripe I >> hear from Ram truck owners who have compared the new 5.7 Hemi to the >> old 5.9 360. Yes, the Hemi has more horsepower and torque, but the old >> 5.9 slams you back harder and quicker when you first punch it because >> it responds instantly. I've also observed the same thing when >> comparing an older cable-throttle 3.5L v6 to the newest >> throttle-by-wire 3.5L v6. > > > The fuel injection on current mechanically operated throttle bodies is > controlled by the computer. I don't see how controlling the butterfly > is inherently any slower than controlling the fuel. And you need both > fuel and air to get the engine to respond. Not true at all. If you slam the throttle open, the computer HAS to respond with fuel at the same rate or the engine will backfire and stall. It cannot "slow down" fuel delivery if you force an increase in air delivery without leaning out the engine to the point that it would backfire, stall, or at least detonate badly. So as long as the foot connects directly to the butterfly valve, the operator can demand instant power and will get it. With full-up TBW on the other hand, the computer has complete authority to open the throttle no faster than the software design allows, and that "allowance" can include all sorts of factors to mitigate emissions and increase economy to bump the CAFE numbers up. Maybe your foot hits the floor in 250 milliseconds, but the computer can insist that the throttle not reach wide-open for 1.5 seconds if it wants to. And thats exactly what people are saying about the 5.7 Hemi versus the old 5.9.
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#78
January 25th 05, 10:40 PM
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Steve wrote:
> Matt Whiting wrote: > >> Steve wrote: >> >>> maxpower wrote: >>> >>>> "James C. Reeves" > wrote in message >>>> ... >>>> >>>>> "Steve" > wrote in message >>>>> ... >>>>> >>>>>> I firmly believe that virtually 100% of the cases of "unintended >>>>>> acceleration" in cars made prior to about 2001 were because of driver >>>>>> error. There's simply NO way that an engine with a mechanical >>>>>> throttle >>>>>> linkage can accelerate unless the return spring breaks, and it >>>>>> doesn't >>>> >>>> >>>> >>>> >>>> "go >>>> >>>>>> back to normal" immediately thereafter- it stays broken. >>>>>> >>>>>> Howver, in recent years more cars are being built with "throttle by >>>> >>>> >>>> >>>> >>>> wire" >>>> >>>>>> in which a computer-controlled servo moves the throttle blades, not a >>>>>> direct mechanical linkage to the accelerator pedal. I know that the >>>>>> systems and software go through tremendous testing, but I no >>>>>> longer feel >>>>>> confident in saying that it "cannot happen" anymore. >>>>>> >>>>> >>>>> Which begs the question...why make a very simple and reliable >>>>> system more >>>>> complicated (with all the associated problems that more complicated >>>> >>>> >>>> >>>> >>>> systems >>>> >>>>> have)? >>>>> >>>>> ITS ALL ABOUT MONEY, no cables, brackets, save on money >>> >>> >>> >>> >>> >>> Yep- the throttle body location can be anywhere and you still use the >>> same accelerator pedal and the same throttle servo. No custom cable >>> lengths. >>> >>>> and supposed to be a faster response for acceleration >>> >>> >>> >>> >>> And the sick and twisted irony is that "throttle by wire" engines are >>> NOTORIOUS for having a sluggish throttle response compared to direct >>> cables. The software always optimizes the throttle opening rate to >>> minimize fuel consumption and emissions, rather than letting you bang >>> the butterflies open instantly the way you can when your right foot >>> is firmly cabled to the throttle blades. That is the NUMBER ONE gripe >>> I hear from Ram truck owners who have compared the new 5.7 Hemi to >>> the old 5.9 360. Yes, the Hemi has more horsepower and torque, but >>> the old 5.9 slams you back harder and quicker when you first punch it >>> because it responds instantly. I've also observed the same thing when >>> comparing an older cable-throttle 3.5L v6 to the newest >>> throttle-by-wire 3.5L v6. >> >> >> >> The fuel injection on current mechanically operated throttle bodies is >> controlled by the computer. I don't see how controlling the butterfly >> is inherently any slower than controlling the fuel. And you need both >> fuel and air to get the engine to respond. > > > Not true at all. If you slam the throttle open, the computer HAS to > respond with fuel at the same rate or the engine will backfire and > stall. It cannot "slow down" fuel delivery if you force an increase in > air delivery without leaning out the engine to the point that it would > backfire, stall, or at least detonate badly. So as long as the foot > connects directly to the butterfly valve, the operator can demand > instant power and will get it. > > With full-up TBW on the other hand, the computer has complete authority > to open the throttle no faster than the software design allows, and that > "allowance" can include all sorts of factors to mitigate emissions and > increase economy to bump the CAFE numbers up. Maybe your foot hits the > floor in 250 milliseconds, but the computer can insist that the throttle > not reach wide-open for 1.5 seconds if it wants to. > > And thats exactly what people are saying about the 5.7 Hemi versus the > old 5.9. Read again what I wrote. I didn't say that the current hemi implementation wasn't slower on throttle response, I simply said this doesn't have to be the case. That is, the design isn't INHERENTLY slower. The designers may choose to be slower, but that isn't an issue with the technology, that is an issue with the designers. Matt
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#79
January 26th 05, 07:07 PM
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Matt Whiting wrote:
> Steve wrote: > >> Matt Whiting wrote: >> >>> Steve wrote: >>> >>>> maxpower wrote: >>>> >>>>> "James C. Reeves" > wrote in message >>>>> ... >>>>> >>>>>> "Steve" > wrote in message >>>>>> ... >>>>>> >>>>>>> I firmly believe that virtually 100% of the cases of "unintended >>>>>>> acceleration" in cars made prior to about 2001 were because of >>>>>>> driver >>>>>>> error. There's simply NO way that an engine with a mechanical >>>>>>> throttle >>>>>>> linkage can accelerate unless the return spring breaks, and it >>>>>>> doesn't >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> "go >>>>> >>>>>>> back to normal" immediately thereafter- it stays broken. >>>>>>> >>>>>>> Howver, in recent years more cars are being built with "throttle by >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> wire" >>>>> >>>>>>> in which a computer-controlled servo moves the throttle blades, >>>>>>> not a >>>>>>> direct mechanical linkage to the accelerator pedal. I know that the >>>>>>> systems and software go through tremendous testing, but I no >>>>>>> longer feel >>>>>>> confident in saying that it "cannot happen" anymore. >>>>>>> >>>>>> >>>>>> Which begs the question...why make a very simple and reliable >>>>>> system more >>>>>> complicated (with all the associated problems that more complicated >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> systems >>>>> >>>>>> have)? >>>>>> >>>>>> ITS ALL ABOUT MONEY, no cables, brackets, save on money >>>> >>>> >>>> >>>> >>>> >>>> >>>> Yep- the throttle body location can be anywhere and you still use >>>> the same accelerator pedal and the same throttle servo. No custom >>>> cable lengths. >>>> >>>>> and supposed to be a faster response for acceleration >>>> >>>> >>>> >>>> >>>> >>>> And the sick and twisted irony is that "throttle by wire" engines >>>> are NOTORIOUS for having a sluggish throttle response compared to >>>> direct cables. The software always optimizes the throttle opening >>>> rate to minimize fuel consumption and emissions, rather than letting >>>> you bang the butterflies open instantly the way you can when your >>>> right foot is firmly cabled to the throttle blades. That is the >>>> NUMBER ONE gripe I hear from Ram truck owners who have compared the >>>> new 5.7 Hemi to the old 5.9 360. Yes, the Hemi has more horsepower >>>> and torque, but the old 5.9 slams you back harder and quicker when >>>> you first punch it because it responds instantly. I've also observed >>>> the same thing when comparing an older cable-throttle 3.5L v6 to the >>>> newest throttle-by-wire 3.5L v6. >>> >>> >>> >>> >>> The fuel injection on current mechanically operated throttle bodies >>> is controlled by the computer. I don't see how controlling the >>> butterfly is inherently any slower than controlling the fuel. And >>> you need both fuel and air to get the engine to respond. >> >> >> >> Not true at all. If you slam the throttle open, the computer HAS to >> respond with fuel at the same rate or the engine will backfire and >> stall. It cannot "slow down" fuel delivery if you force an increase in >> air delivery without leaning out the engine to the point that it would >> backfire, stall, or at least detonate badly. So as long as the foot >> connects directly to the butterfly valve, the operator can demand >> instant power and will get it. >> >> With full-up TBW on the other hand, the computer has complete >> authority to open the throttle no faster than the software design >> allows, and that "allowance" can include all sorts of factors to >> mitigate emissions and increase economy to bump the CAFE numbers up. >> Maybe your foot hits the floor in 250 milliseconds, but the computer >> can insist that the throttle not reach wide-open for 1.5 seconds if it >> wants to. >> >> And thats exactly what people are saying about the 5.7 Hemi versus the >> old 5.9. > > > Read again what I wrote. I didn't say that the current hemi > implementation wasn't slower on throttle response, I simply said this > doesn't have to be the case. That is, the design isn't INHERENTLY > slower. The designers may choose to be slower, but that isn't an issue > with the technology, that is an issue with the designers. > > > Matt The way I read the comment was such that it implied that conventional throttling COULD be made to respond slower also. It can't. What threw me off was your statement "I don't see how controlling the butterfly is inherently any slower than controlling the fuel" since the driver *never* directly controls the fuel in anything except a diesel. Even with a carburetor, the driver controls the *air* and the fuel is added in response- same with EFI and a cable throttle. Only a (non computerized) diesel gives the driver direct control over fuel flow. So it seemed to me that you were saying that since the computer still controls fuel in a cable-throttle system, it can can slow the engine response independently of the driver's foot on the throttle.
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#80
January 26th 05, 07:52 PM
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"Steve" > wrote in message ... > Matt Whiting wrote: > > > Steve wrote: > > > >> Matt Whiting wrote: > >> > >>> Steve wrote: > >>> > >>>> maxpower wrote: > >>>> > >>>>> "James C. Reeves" > wrote in message > >>>>> ... > >>>>> > >>>>>> "Steve" > wrote in message > >>>>>> ... > >>>>>> > >>>>>>> I firmly believe that virtually 100% of the cases of "unintended > >>>>>>> acceleration" in cars made prior to about 2001 were because of > >>>>>>> driver > >>>>>>> error. There's simply NO way that an engine with a mechanical > >>>>>>> throttle > >>>>>>> linkage can accelerate unless the return spring breaks, and it > >>>>>>> doesn't > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> "go > >>>>> > >>>>>>> back to normal" immediately thereafter- it stays broken. > >>>>>>> > >>>>>>> Howver, in recent years more cars are being built with "throttle by > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> wire" > >>>>> > >>>>>>> in which a computer-controlled servo moves the throttle blades, > >>>>>>> not a > >>>>>>> direct mechanical linkage to the accelerator pedal. I know that the > >>>>>>> systems and software go through tremendous testing, but I no > >>>>>>> longer feel > >>>>>>> confident in saying that it "cannot happen" anymore. > >>>>>>> > >>>>>> > >>>>>> Which begs the question...why make a very simple and reliable > >>>>>> system more > >>>>>> complicated (with all the associated problems that more complicated > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> systems > >>>>> > >>>>>> have)? > >>>>>> > >>>>>> ITS ALL ABOUT MONEY, no cables, brackets, save on money > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> Yep- the throttle body location can be anywhere and you still use > >>>> the same accelerator pedal and the same throttle servo. No custom > >>>> cable lengths. > >>>> > >>>>> and supposed to be a faster response for acceleration > >>>> > >>>> > >>>> > >>>> > >>>> > >>>> And the sick and twisted irony is that "throttle by wire" engines > >>>> are NOTORIOUS for having a sluggish throttle response compared to > >>>> direct cables. The software always optimizes the throttle opening > >>>> rate to minimize fuel consumption and emissions, rather than letting > >>>> you bang the butterflies open instantly the way you can when your > >>>> right foot is firmly cabled to the throttle blades. That is the > >>>> NUMBER ONE gripe I hear from Ram truck owners who have compared the > >>>> new 5.7 Hemi to the old 5.9 360. Yes, the Hemi has more horsepower > >>>> and torque, but the old 5.9 slams you back harder and quicker when > >>>> you first punch it because it responds instantly. I've also observed > >>>> the same thing when comparing an older cable-throttle 3.5L v6 to the > >>>> newest throttle-by-wire 3.5L v6. > >>> > >>> > >>> > >>> > >>> The fuel injection on current mechanically operated throttle bodies > >>> is controlled by the computer. I don't see how controlling the > >>> butterfly is inherently any slower than controlling the fuel. And > >>> you need both fuel and air to get the engine to respond. > >> > >> > >> > >> Not true at all. If you slam the throttle open, the computer HAS to > >> respond with fuel at the same rate or the engine will backfire and > >> stall. It cannot "slow down" fuel delivery if you force an increase in > >> air delivery without leaning out the engine to the point that it would > >> backfire, stall, or at least detonate badly. So as long as the foot > >> connects directly to the butterfly valve, the operator can demand > >> instant power and will get it. > >> > >> With full-up TBW on the other hand, the computer has complete > >> authority to open the throttle no faster than the software design > >> allows, and that "allowance" can include all sorts of factors to > >> mitigate emissions and increase economy to bump the CAFE numbers up. > >> Maybe your foot hits the floor in 250 milliseconds, but the computer > >> can insist that the throttle not reach wide-open for 1.5 seconds if it > >> wants to. > >> > >> And thats exactly what people are saying about the 5.7 Hemi versus the > >> old 5.9. > > > > > > Read again what I wrote. I didn't say that the current hemi > > implementation wasn't slower on throttle response, I simply said this > > doesn't have to be the case. That is, the design isn't INHERENTLY > > slower. The designers may choose to be slower, but that isn't an issue > > with the technology, that is an issue with the designers. > > > > > > Matt > > > The way I read the comment was such that it implied that conventional > throttling COULD be made to respond slower also. It can't. What threw me > off was your statement "I don't see how controlling the > butterfly is inherently any slower than controlling the fuel" since the > driver *never* directly controls the fuel in anything except a diesel. > Even with a carburetor, the driver controls the *air* and the fuel is > added in response- same with EFI and a cable throttle. Only a (non > computerized) diesel gives the driver direct control over fuel flow. So > it seemed to me that you were saying that since the computer still > controls fuel in a cable-throttle system, it can can slow the engine > response independently of the driver's foot on the throttle. > > > since the driver *never* directly controls the fuel in anything except a diesel. Even with a carburetor, the driver controls the *air* and the fuel is added in response- Wtih a carburetor the driver does control fuel on acceleration.
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