Toyota stalling may be linked to on-board computers, electronic control module
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From: hls on 7 Dec 2009 16:35 "m6onz5a" <corvair(a)comcast.net> wrote in message news:abb95d2a-529e-4ee4-9eac-90fed63d1117(a)z35g2000prh.googlegroups.com... On Dec 7, 11:46 am, "Jeff Strickland" <crwlrj...(a)yahoo.com> wrote: > The problem is that Toyota (and others) are using what is termed, fly by > wire. > > In fly by wire, the gas pedal is not mechanically connected to the > throttle > body. The gas pedal has a servo that tells the computer what the angle is, > and the computer then sets the throttle body with a stepper motor to match > the angle of the gas pedal. The throttle position sensor has been used for years in different embodiments, some essentially drive by wire. I know there are differences, but the technology is not totally new nor very experimental. I remember when total drive by wire came up in rec.autos.tech, a lot of us really didnt like where that was leading. I still dont.
From: Vic Smith on 7 Dec 2009 16:50 On Mon, 07 Dec 2009 08:23:33 -0600, Don Stauffer <stauffer(a)usfamily.net> wrote: >dr_jeff wrote: >> john wrote: >> >> Really. The ECUs definitely have problems, but please show us a better >> way that doesn't involve electronics. Carbs worked well, but wasted >> fuel. Without electronics, are air would be dirtier, we would use more >> fuel. >> > >Why did carbs "waste" fuel? They used enrichment at high manifold >pressure, but so do FI systems. The last generation of carburetors were >quite good. What really is the difference between a carb and a throttle >body electronic injection system? One is controlled by a pneumatic >computer, the other by an electronic one. Admittedly electronic >computers can be miniaturized, and add more computation. > >Essentially the carbs of the seventies and eighties DID have computers. > The amount of measurement of their environment and the amount of >control was remarkable. There were even the deceleration controls that >got rid of richness during trailing throttle. They were marvels of >fluidic computing. > Maybe the carbs were "improved" in their last years, but I never had a carb that was as good as the electronic controlled fuel injection I've had, especially when it gets real cold out. Or for MPG. Whether throttle body of port injection. I stayed with carbs longer than most, but finally came over. Didn't like the idea of fuel pump in the tank, and replacing expensive injectors. Then I priced a rebuilt 4-bbl for a 350 and came over. Think it was about 600 bucks. Previous rebuilt Carter 2-bbl I'd bought had cost me - $25. --Vic
From: hls on 7 Dec 2009 17:11 "Vic Smith" <thismailautodeleted(a)comcast.net> wrote in message > Maybe the carbs were "improved" in their last years, but I never had a > carb that was as good as the electronic controlled fuel injection I've > had, especially when it gets real cold out. Or for MPG. > Whether throttle body of port injection. Ive had both throttle body (on a damn Fiero), and tons of tune port injection engines. For my part, that throttle body unit was a POS, and perfectly mated to the car and engine. TPI outperformed every other form if aspiration for me. Carburetors did work well enough, but the "average" carburetor didnt even compare with injection. Admittedly, there were special carburetors available, like Webers, but I never had that setup and cannot comment.
From: Tegger on 7 Dec 2009 17:15 "hls" <hls(a)nospam.nix> wrote in news:DMGdnUC4lMmn6IDWnZ2dnUVZ_jidnZ2d(a)giganews.com: > > "m6onz5a" <corvair(a)comcast.net> wrote in message > news:abb95d2a-529e-4ee4-9eac-90fed63d1117(a)z35g2000prh.googlegroups.com. > .. On Dec 7, 11:46 am, "Jeff Strickland" <crwlrj...(a)yahoo.com> wrote: >> The problem is that Toyota (and others) are using what is termed, fly >> by wire. >> >> In fly by wire, the gas pedal is not mechanically connected to the >> throttle >> body. The gas pedal has a servo that tells the computer what the >> angle is, and the computer then sets the throttle body with a stepper >> motor to match the angle of the gas pedal. > > The throttle position sensor has been used for years in different > embodiments, > some essentially drive by wire. I know there are differences, but the > technology > is not totally new nor very experimental. > > I remember when total drive by wire came up in rec.autos.tech, a lot > of us really didnt like where that was leading. I still dont. > > You can thank emissions and CAFE regulations for throttle-by-wire. With all the easy gains long accomplished, it takes some serious trickery to get the last little bit of blood out of that particular stone. And, I learned today, it appears there is a liability-regulation issue behind the "start button". My understanding is that the "start button" originally had a half-second delay before it would shut off the engine. The problem was that people were hitting it accidentally and causing unexpected shutdowns in traffic, leading to a potential liability situation. Therefore, the button was given a THREE SECOND delay. Apparently the drivers of at least some of these "runaways" HAD pushed the "start button", but panicked when the button did not shut the engine down immediately (three seconds must seem like an eternity in such a situation). Source for above: Letter to the Editor in the Wall Street Journal, Sat/Sun Dec5/6, page A20. Title of the letter: "Lawyers Shouldn't Be Designing Cars". The letter also mentions a previous article in the WSJ of Dec2 ("Bring Back the 'Off' Switch"), which I missed reading. -- Tegger
From: Tegger on 7 Dec 2009 17:41
Don Stauffer <stauffer(a)usfamily.net> wrote in news:4b1d0fe5$0$87077 $815e3792(a)news.qwest.net: > dr_jeff wrote: >> john wrote: >> >> Really. The ECUs definitely have problems, but please show us a better >> way that doesn't involve electronics. Carbs worked well, but wasted >> fuel. Without electronics, are air would be dirtier, we would use more >> fuel. >> > > Why did carbs "waste" fuel? They used enrichment at high manifold > pressure, but so do FI systems. The last generation of carburetors were > quite good. What really is the difference between a carb and a throttle > body electronic injection system? One is controlled by a pneumatic > computer, the other by an electronic one. Admittedly electronic > computers can be miniaturized, and add more computation. The primary problem with carburetors was that they reacted far too slowly for feedback emissions control that would satisfy the law. They were OK when emissions regs were laxer, but in North America after 1990, the laws were so strict that it was near impossible to make a carb-fed engine emissions-compliant. Some manufacturers were able to get away with throttle-body injection for a while, but inevitable fuel-dropout in the intake runners (and subsequent mixture-control problems) put paid to those systems. And throttle-body still had far slower reaction time than port-injection. Areas of the world without strict emissions controls continued to use carbs for a long time. Some might /still/ be using carbs, I don't know. > > Essentially the carbs of the seventies and eighties DID have computers. > The amount of measurement of their environment and the amount of > control was remarkable. Their complexity and propensity for getting out-of-order was also remarkable. Good riddance to them. -- Tegger |