electronic throttle
in [Technical]
|
From: jim beam on 8 Mar 2010 22:14 On 03/08/2010 03:27 AM, Bill Putney wrote: > jim beam wrote: > >> /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. > > You know, Jim - it boils down to this - you think you can predict how a > human being is going to react when faced with a sudden emergency when > they have never given a nano-seconds thought in the past or been trained > to deal with that particular said emergency. That's ludicrous. i'm not predicting anything - i'm observing reality and pointing it out to you since you don't want to see it for yourself. > > The person will be experimenting using a brain that is in panic mode and > doesn't understand or can't think fast enough to properly analyze the > the ramifications of the tools (shifter, etc.) available to them at the > moment to save their own life. Hands with bullet holes in them when > being shot - yeah - makes a lot of sense - but that's the same kind of > "irrational" reaction you get when the brain is overloaded and startled. you've just defeated your own argument... -- nomina rutrum rutrum
From: jim beam on 8 Mar 2010 22:15 On 03/08/2010 04:28 PM, clare(a)snyder.on.ca wrote: > On Sun, 07 Mar 2010 22:24:45 -0800, jim beam<me(a)privacy.net> wrote: > >> 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". > > > OK then - lets be accurate and say "adequate". Won't get that either. not for casual comfort, no. but this is academic unless we're buying bills "panic pump" theory, which is not observed in reality. >> >> >>> 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 22:16 On 03/08/2010 05:27 PM, Dave wrote: > > "jim beam" <me(a)privacy.net> wrote in message > news:0fOdnb-8aZVkBwnWnZ2dnUVZ_oIAAAAA(a)speakeasy.net... >> 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? >> > > Notoriously....But the point I was making is that vacuum wipers slow to > a crawl or even stop with ANY opening of the throttle. Even when working > as designed. And yes, I'm old enough to know. and unless your vacuum diaphragm is old enough to leak, you can stop the car with full vacuum assist if you're not pumping the brake. -- nomina rutrum rutrum
From: jim beam on 8 Mar 2010 22:29 On 03/07/2010 09:27 PM, Jim Warman wrote: > 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... don't german cars already do this? one power line, one signal line, and reader/switch modules on each light? > > > "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. >> >> >> >> >> > > -- nomina rutrum rutrum
From: Floyd Rogers on 8 Mar 2010 23:54
"jim beam" <me(a)privacy.net> wrote > On 03/07/2010 09:27 PM, Jim Warman wrote: >> 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... > > don't german cars already do this? one power line, one signal line, and > reader/switch modules on each light? BMWs for the last 10 years. They also notify you of burned out bulbs (via lack of voltage drop in the circuit.) Now, you see BMW drivers that don't use their signals (not my family!), but it's not because they're in-operative. FloydR |