electronic throttle
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From: Jim Warman on 8 Mar 2010 00:27 Actually, in the modern automobile, the gas pedal tells the PCM that you want to go faster... A lot of you folks are gong to be disappointed in the near future... The headlight switch tells the BCM that you want to turn on some lights... the turn signal switch tells the BCM that you wnat to turn on some flashing lights... This is gonna be cool... "Jeff Strickland" <crwlrjeff(a)yahoo.com> wrote in message news:hmuep4$qd2$1(a)news.eternal-september.org... > > "jim beam" <me(a)privacy.net> wrote in message > news:uqOdnfZrX4eWKQ_WnZ2dnUVZ_qIAAAAA(a)speakeasy.net... >> On 03/06/2010 09:03 AM, Jeff Strickland wrote: >>> "jim beam"<me(a)privacy.net> wrote in message >>> news:fvudnV-hwr-Z6A_WnZ2dnUVZ_rednZ2d(a)speakeasy.net... >>>> if you buy all this fear-mongering idiocy that electronic throttle is a >>>> problem, and that brakes, transmissions and ignition kill switches can >>>> all >>>> simultaneously fail causing a driver to lose control, it might be worth >>>> auto manufacturers of all stripes to adopt a slightly different >>>> implementation of electronic throttle [e.t.] - if not for mechanical >>>> reasons, but to shut the idiots up. >>>> >>>> first, lets understand e.t. functionality: >>>> >>>> 1. open the throttle when demanded >>>> 2. close throttle when demanded >>>> 3. allow "demand" to account for additional requirements like >>>> a. de-throttle on shifting for automatics, >>>> b. throttle appropriate to load at high demand [eg. full throttle at >>>> low >>>> rpms can choke an engine and significantly reduce output - thus >>>> de-throttle until revs support full open] >>> >>> >>> The functionality is even easier than that -- open the throttle plate >>> when >>> the gas pedal is pressed and close the throttle plate when the gas pedal >>> is >>> released. You can get bogged down in semantics if you want, but the >>> functiionality is really that simple Go when the pedal is pressed and >>> stop >>> going when the pedal is released. At the end of the day, anything else >>> is a >>> variation on pushing the pedal down or releasing the pedal so that it >>> comes >>> back up. >> >> yeah, that meets conditions 3.a & 3.b. oh, wait, no it doesn't. >> > > > This is the most important part? > > It's nonsense! The gas pedal does two things, opens the throttle plate and > closes the throttle plate. Period. > > You should ride the bus. > > > > >
From: jim beam on 8 Mar 2010 00:44 On 03/07/2010 02:34 PM, clare(a)snyder.on.ca wrote: > On Sun, 07 Mar 2010 07:12:45 GMT, "MasterBlaster" > <Nobodys.Home(a)My.Place> wrote: > >> >> "jim beam" wrote: >> >>>> Jeff Strickland wrote: >>>> YOU (probably in a drunken stupor) said it is feasable to use a mechanical >>>> linkage to open the throttle, then use the some other means to close it. >>>> Sheer stupidity. >>> >>> then you're not reading what i said or understanding the control principle. >> >> I think I understand it. Let's see... >> >> Similar concept to a Quadrajet carburetor's secondary throttle plate? >> In that example, the secondary's linkage is connected to the primary's, >> and moves when you floor the gas pedal, but if the choke hasn't opened >> all the way yet, then the secondary plates are locked, and not permitted to >> open, to prevent the engine from bogging or even stalling when cold. >> >> As above, with your cable/computer hybrid system, flooring the gas pedal will still >> allow the spring-loaded linkage to move, but the throttle plate will only follow the >> linkage and open *if* the computer thinks it's safe to do so. If the system sees >> you're also pushing hard on the brake pedal, or the car is sliding sideways, or the >> ABS system kicks in on a slippery road, or the magic eye scans the invisible bar >> code on the speed limit sign and decides you're going too fast, it can override the >> gas pedal's position and close the throttle, either partially or completely. All you'd >> feel is a decrease in power, and more resistance at the gas pedal as the throttle >> plate was pulled closed against the "follow-me" spring in the linkage. >> Sounds a lot like the "Traction Control" systems already in use on some cars. >> > "tandem throttle" Where the computer cannot OPEN the throttle unless > the cable op throttle is also open, but the computer can close the > throttle any time it likes. The computer can also control the opening > of the throttle within the confines of the limit established by the > cable op throttle. that's it. -- nomina rutrum rutrum
From: jim beam on 8 Mar 2010 01:24 On 03/07/2010 02:47 PM, clare(a)snyder.on.ca wrote: > On Sun, 07 Mar 2010 08:24:21 -0800, jim beam<me(a)privacy.net> wrote: > >> On 03/07/2010 08:10 AM, Bill Putney wrote: >>> jim beam wrote: >>>> On 03/06/2010 08:26 PM, Bill Putney wrote: >>> >>>>> I don't necessarily disagree with the rest of your post, but that part >>>>> of your post is definitely incorrect. Have you ever played with your >>>>> power brakes while simultaneously pressing the accelerator? Anything >>>>> more than one or two initial stabs at the brakes depletes the vacuum >>>>> stored in the booster, and with even slight power simultaneously being >>>>> demanded of the engine, the vacuum is not enough to directly power the >>>>> brakes, much less re-charge the vacuum in the booster. >>>> >>>> i have done this. with the engine off, the vacuum remains until the >>>> pedal is released - thus if you stomp the pedal and keep it there, you >>>> don't need to keep replenishing the vacuum. and you will stop the car. >>>> with the engine running, there is no vacuum issue, and the brakes are >>>> still powerful enough to stop the car. on my honda anyway. >>> >>> I have real trouble believing that a large majority of people would, in >>> a sudden inadvertent acceleration situation, be content to press the >>> brakes one time and not try to pump them once or twice. >> >> why? if the car in front of you suddenly jams on their brakes, do you >> apply then release your pedal? i think your answer is "no" - unless >> you're skidding and know what cadence braking is. and if you know what >> cadence braking is, you should know that to stop a car with the engine >> on full throttle, you apply the brakes hard and quickly - you don't >> monkey about with multiple brake applications that can cause excess >> heating and fade. >> >> >>> After that, the >>> brakes will be almost totally ineffective because of loss of vacuum. >> >> no. fade maybe, but vacuum is always present if the engine is running. >> even if it's not, you still have vacuum reserve for three applications. >> >> >>> >>>>> People don't believe that, but try it on your car: On a deserted road at >>>>> highway speed, stab the brake pedal a couple of times while holding the >>>>> gas pedal down a little bit to load the engine slightly (this works >>>>> anywhere from slight to WOT throttle). I guarantee you (unless your >>>>> brake booster gets its vacuum from something besides the intake vacuum - >>>>> like a separate electric motor-driven vacuum pump) that after two or >>>>> more stabs at the brake pedal, the braking power will be extremely low - >>>>> so low that the engine will have no trouble overpowering the brakes. No >>>>> vacuum in the booster essentially equals no brakes. >>>> >>>> with respect, i think you're confusing vacuum with fade... >>> >>> No - I'm not. While you could certainly induce fade with a certain >>> prolonged script of usage of the brakes, what I'm talking about is true >>> over what I would say would be the real world typical scenario (before >>> the fade issue becomes real - which - yes - it would over a longer >>> period, but not likely if the 2 or 3 stabs had already occurred in the >>> relatively short period that I would expect). It is a fact that the >>> vacuum cannot recharge with almost no vacuum in the intake - it doesn't >>> recharge by magic. I guarantee you that after a third stab of the brakes >>> on an engine vacuum-driven power brake car, the brakes will loose the >>> fight with the engine - fade has nothing to do with that over the first >>> few seconds that we would be talking about (during which the first 2 or >>> 3 stabs would occur real world). >> >> if that is your experience, then i think you must have a vacuum leak. >> even with wide open throttle, there is sufficient vacuum in the manifold >> to create significant braking assist. >> > > Sorry Jim - but you are wrong. > A diesel engined vehicle with a mechanical vacuum pump would work as > you envision - but under any substantial load there is not enough > manifold vacuum produced to provide full braking assist. i didn't say "full". > With both > feet on the brake pedal a strong man MAY be able to provide enough > brake line pressure to stop the car at half throttle. /if/ the driver has pressed and released the pedal a couple of times. why they would do that though is something i don't follow. -- nomina rutrum rutrum
From: jim beam on 8 Mar 2010 01:35 On 03/07/2010 02:38 PM, Bill Putney wrote: > jim beam wrote: >> On 03/07/2010 12:42 PM, Bill Putney wrote: > >> how did you manage before the days of vacuum assist? > > In spite of my having gotten my driver's license in about 1966 or 67, My > family nor I has ever owned a vehicle without power brakes since then. I > did however drive someone's car to an airport one time that did not have > power brakes - and I must say - I thought something was seriously wrong > with the brakes. Later, I even loudly complained to the owner for having > me drive their car in such a dangerous condition (they were a family > friend). It was explained to me that that was a car without power brakes > - and was typical of them. All I have to say is "WOW". then your experience is not typical - and more importantly, doesn't qualify you to generalize! > >>> - the >>> engine will likely overcome the brakes in being able to sustain highway >>> speeds (and this is before fade comes into the picture). >> >> fade is a feature of people that don't brake decisively and let the >> vehicle speed up again. or defective design/parts. > > Beating the dead horse, but we're talking about two different things - > vacuum depletion and fade. We're going in circles. so stop flip-flopping your argument. you don't get fade if you simply stomp the pedal and you don't deplete vacuum either. > >>> Saying that 63 sq. in. is a big surface area and so even a tiny little >>> vacuum will give you huge force means nothing. Fact is the assist force >>> on the diaphragm with the very low vacuum under acceleration is less >>> than 15% of what it was designed to use under normal stored vacuum >>> conditions. >> >> how did anyone drive a car before the days of vacuum assist? > > From my one time of driving that car without assist - that's a good > question. Stopping distances must have been absolutely awful. not at all. servo brakes are much better, but brakes without were just what you got used to. even today, if i drive my friend's bmw, i have to be careful the first couple of brake applications because i'm used to pressing my honda pedal much harder - i nearly put myself through the windshield. > >>>> you're supposed to apply the brakes and keep them on. only if you >>>> release do you lose vacuum. >>> >>> Right or wrong, many people were taught to pump the brakes. Some people >>> will in fact pump the brakes, for any number of reasons. >> >> some people will hold their foot on the gas believing it to be the >> brake too. > > That's a whole other problem of course. it's /the/ problem if you ask me. > >>>> ...again, if that's your experience, i think you're working with >>>> something not representative of most vehicles. certainly not anything >>>> post 1980. >>> >>> Nope. Your assumptions are wrong on both counts. >> >> why? why does my car come to halt when i brake hard at full throttle? >> why doesn't yours? > > No argument if it's a single long application of the brakes. Are we > talking about after the brakes are pumped a couple of times after > application of throttle? why? who would do that if they're trying to stop an out-of-control vehicle? > My experiences were on things like an '86 > Subaru Turbo wagon, an '88 Cadillac DeVille, '99 Buick Century, and 2 > 2nd generation Chrysler Concordes - all in tip-top mechanical shape. ugh. can't you drive decent cars for pete's sake? > >>>> where is your "theory" that people pump brakes? i saw someone on a >>>> freeway in rain in los angles one time, skating along with their >>>> brakes locked, car gently rotating, and the look on her face was that >>>> of someone trying to break the pedal off she was pushing it so hard. >>>> there's no way that person, as an average driver, was going to let off >>>> that pedal, and thus, even though she was going to crash, she was not >>>> going to lose vacuum. >>> >>> You keep throwing in scenarios totally different than what we're talking >>> about. >> >> no, i'm pointing out the flaw in the argument. for the argument to be >> valid, it has to work universally. otherwise you need to qualify it to >> specific circumstances. > >>> Again - you can't prove your claim that hardly anyone pumps the >>> brakes any more than my claim that a lot of people would pump the brakes >>> - so from that standpoint, it's what we each want to believe until >>> someone presents some hard evidence. Your observations in life are no >>> more or no less valid than mine are - so quit belittling mine and >>> touting your just as anecdotal observations as more than they are. >> >> but dude, why do we have abs? it's not because people pump the brakes >> because then they'd be unnecessary! > > Some people were taught and developed a lifelong habit of pumping brakes. some??? damned few dude - that's why we have abs. > >>>>> Admittedly, my theory that some percentage of drivers would pump the >>>>> brakes is not provable as far as I know, but I do state it as >>>>> conjecture, not as fact as you are stating your argument. >>>> >>>> with respect, you're projecting your own behavior as representative of >>>> everyone. it's not true. >>> >>> Oh - I see - so no one pumps there brakes, either in accident avoidance >>> situations or if faced with runaway acceleration. Got it. (I don't >>> buy it.) >> >> abs. that's the reality, like it or not. > > Not all cars have ABS. they do nowadays. > Were not talking about what people should do. I'm > saying what many - not just 1 in 100 - *will* do in the situation we are > talking about which is unexpected acceleration. with respect, you are not representative. see above. > >>>> indeed, but i'm pointing out the fact that refutes your supposition - >>>> typical panicked drivers do not let off the brake pedal. >>> >>> That's your theory and your belief. No more or less valid than mine of >>> the opposite. >>> >> >> you're entitled to your opinion, but preface them as such. "i believe >> that..." is quite different from the definitive statements you've been >> making like "the ... will absolutely *not* ... " etc., because it's >> not true. > > I said that about an engine under acceleration not developing enough > vacuum to give anything close to expected braking power once the initial > booster charge is depleted. That is a fact. but it's not. there is still sufficient vacuum to generate considerable assist. not as much as ideal, but it's still there. > Therefore I didn't qualify > it, and I didn't need to. Where I did give opinion, I identified it as > such. Shall we go thru the math on the 15% vacuum again? sure. after we go through the fact that you've never driven a vehicle without it and thus don't have experience. -- nomina rutrum rutrum
From: jim beam on 8 Mar 2010 01:36
On 03/07/2010 07:13 PM, Dave wrote: > > "jim beam" <me(a)privacy.net> wrote in message > news:F4udnUySrZ3GZQ7WnZ2dnUVZ_vQAAAAA(a)speakeasy.net... >> On 03/07/2010 09:52 AM, Bill Putney wrote: >>> jim beam wrote: >>>> On 03/07/2010 08:16 AM, Bill Putney wrote: >>>>> dsi1 wrote: >>>>> >>>>>> I certainly believe you. You can get a feel for the amount of reserve >>>>>> vacuum boost on your car by simply repeatedly pressing down on the >>>>>> brakes without starting your engine. If your brakes are working >>>>>> properly, you'll feel the pedal getting firmer until you'll only be >>>>>> able to move the brake pedal a couple of inches of deflection. At >>>>>> that >>>>>> point, you'll have used up all your vacuum reserve. I figure that you >>>>>> should be able to get around 3 stabs at the brakes with mostly full >>>>>> boost. This means you'll only get maybe two chances for full braking >>>>>> after the initial attempt at braking. That's the breaks I guess. :-) >>>>> >>>>> My recollection is that boost is noticeably diminished after the >>>>> second >>>>> stab, greatly diminished by the third stab - engine overpowers brakes >>>>> for most common vehicles. >>>>> >>>> >>>> maybe if the engine is stopped and vacuum gone. but if the engine is >>>> running, you still have vacuum... >>> >>> Then give me some vacuum numbers for idle, and in gear light, moderate, >>> and heavy acceleration for a typical engine. If you can show that >>> moderate to heavy acceleration vacuum levels are anywhere near idle >>> vacuum levels, then I'll concede. >> >> dude, for the typical vacuum diaphragm, you only need the smallest >> vacuum to significantly boost brake pressure. do the math. >> > > You have never driven a vehicle with vacuum actuated wipers, have you? no. did they leak? -- nomina rutrum rutrum |