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Old 11-04-2009, 11:37 AM   #21
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Is there a way to know if your model car has rev limiting? I see that redline on my tach, and I always assumed that since there is a computer controlling the engine, that the computer would simply not allow revs past that point. But unless I was at the dealer, and had already signed the "Cash for Clunkers" paperwork, no way am I going to find out the hard way!

My brother is a "car guy", and he was thinking that shutting down the injectors with the throttle open would result in a lean mixture would could also cause damage (probably less than over-revving though). It almost seems like they would need to go zero fuel, and then max again to cycle and keep under the redline?

I'll also add that it seems crazy that hitting the brake does not limit the engine in all cars. All that info is already going to the computer, so just add that case. Another safety item, that would take some added hardware would be for those cases where people push the gas, thinking they are pushing the brake, and then push harder when the car does not stop, then just get panicked into pushing harder and harder. There should be a shutdown switch under the gas pedal - if you are pushing really hard (like you would a brake pedal in an emergency), shut the engine down to an idle. Extra switch, wire and computer input though.

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Old 11-04-2009, 11:40 AM   #22
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Dw had a Pontiac Sunbird that had the opposite problem, the gas pedal broke, and she could only go as fast as the idle would take her, about 3 mph...........and yes, it was MY FAULT.........
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Old 11-04-2009, 12:02 PM   #23
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Originally Posted by REWahoo View Post
True, and that isn't what happened in this situation. It wasn't the driver who made the call:
If I was the passenger of a car that was out of control doing 100 MPH towards a fast approaching intersection, the thought of pulling out my cell phone and calling 911 would never cross my mind.
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Old 11-04-2009, 01:38 PM   #24
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There should be a shutdown switch under the gas pedal - if you are pushing really hard (like you would a brake pedal in an emergency), shut the engine down to an idle.
You might press that hard if being chased by Freddie Kruger or a train at a crossing.
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Old 11-04-2009, 01:59 PM   #25
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You might press that hard if being chased by Freddie Kruger or a train at a crossing.
Volvo actually had a prototype combination pedal they tested recently - push it to brake, twist from side to side (or through an arc?) for throttle.

Makes sense - the push is always associated with STOP. IIRC, the time saved from having to lift your foot from the gas to the brake meant something like 30 feet of stopping difference at high speeds. But, like the Dvorak keyboard, change is hard.


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Old 11-04-2009, 04:09 PM   #26
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From my limited knowledge of cars and what I know people have done with them in my lifetime....

First... older cars did not need rev limiters... most just couldn't go that high in the first place... they were limited by their internal friction or whatever it was... My friends and I used to rev up the engines... really flooring the car all the way... most would not pass redline...

As for putting the car in drive at that time... I knew a few who would do it.... one car would just peel out like crazy... smoking the tires for a long time... one car just hopped up and down trying to get traction... one car snapped a u-joint.... one blew his tranny....

The rev limiter on my car (IIRC) works the electronics somehow... I do not know what they do with the fuel... but when you hit it, it is 'hard'... the engine has zero power for that second or two...

I would put the car in neutral, park, reverse... first... any gear that would either stop me or slow me down a lot... most cars only go 30 to 40 max in first... believe me... if you are going fast and downshift to a lower gear... you know it quickly... I did and my back wheels locked up... (but I bet the Lexus has a feature that will not allow the tranny to downshift IF you are going to fast...)
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Old 11-04-2009, 05:37 PM   #27
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..................First... older cars did not need rev limiters... most just couldn't go that high in the first place... they were limited by their internal friction or whatever it was... My friends and I used to rev up the engines... really flooring the car all the way... most would not pass redline............................
Rev limiters started being used in the 1980s with the introduction of electronic control systems on cars and trucks. Initially they were used to limit vehicle top speed to cost reduce driveshaft systems on rear wheel cars. An unbalanced driveline will explode if the car reaches its resonant frequency and raising the resonant frequency of the driveline costs money. Later its use was expanded to keep top speeds within the rated speed range for original equipment tires on front wheel drive vehicles. Since it is essentially free, it was further expanded to limit the free rev rpm in neutral gear to prevent accidental engine damage.
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Old 11-04-2009, 07:25 PM   #28
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Yup...the old flat tappet cars most of us grew up with had limiters called valve float.

The newer systems with true limiters are pretty cool the way they interrupt ignition. Import drag racers bring rpm's to the limiter just before launch. Some even use a 2 step/stage limiter. It's different than what you'd normally see and hear at the starting line. Lots of banging and popping, then they sidestep the clutch and look like they're shot out of a cannon.
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Old 11-04-2009, 09:42 PM   #29
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This clearly is a user error. I tried this on the freeway. I slowed down to 55 surface road traffic and gunned it. It took 45 to almost a minute to reach 120 mph. The distance the car traveled when you are going too fast. It wil make your hair stand. Forty five second is a long time to fix the problem when you realize you are going too fast.
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Old 11-04-2009, 10:01 PM   #30
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I'm glad you posted this because I never in a million years would have thought to shift to neutral if my car wouldn't slow down, and now I know. I'm going to poll my family and see if they knew to do this--I'm really not sure it's "the obvious" thing to do for most people.
Those who are accustomed to driving a manual transmission would be most likely to remember this. If you've only ever driven an automatic, you probably wouldn't think of it.
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Old 11-04-2009, 10:40 PM   #31
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This clearly is a user error. I tried this on the freeway. I slowed down to 55 surface road traffic and gunned it. It took 45 to almost a minute to reach 120 mph. The distance the car traveled when you are going too fast. It wil make your hair stand. Forty five second is a long time to fix the problem when you realize you are going too fast.
Where do you live-Bonneville?

This whole thing reminds me of MORE reasons to love my ancient rice burner:
- No electronic speed controls to go crazy
- A manual transmission that makes it simple and intuitive to isolate the engine from the rest of the drivetrain.
- A puny motor that could easily be reigned in by my brakes.
- An engine that would helpfully throw a rod at engine speeds above 6000 rpm
- An inability to achieve 120 MPH even downhill and with a hurricane gale from the rear.
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Old 11-04-2009, 11:33 PM   #32
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Thanks for that reminder!
No, no, thefed was kidding when he said not to shift back into drive while moving!

If you had shifted an automatic trans into neutral while moving, just get on the gas some to boost engine speed up to roughly match road speed before shifting back into Drive. This will avoid the sudden engine braking effect. It's like driving a manual trans in that effect, matching engine speed to road speed before letting out the clutch.
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Old 11-04-2009, 11:59 PM   #33
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..........Also, once I was testdriving a car that stalled going downhill on a busy 45 mph road. I could still steer but it took all my strength to wrest the car onto the shoulder and braking was equally difficult.
With hydraulically-boosted steering (all power steering cars and trucks except for a few recent cars/small SUV's with electric steering), with the engine dead, the Power Steering Pump is stopped. That leaves the straight mechanical non-boosted path. Which is like someone just as strong as you, turning the wheel left, while you're trying to turn right!
Engine quitting while in a tight right turn is not nice... tend to keep turning...

Power Brakes - With the exception of certain cars of the 70's/80's that had hydraulically-boosted brakes, they are engine-vacuum boosted. Vacuum is highest at engine idle, lowest at wide open throttle. For safety, the Power Brake Booster (the round dish or bowl-like object mounted to engine side of firewall, right in front of driver, the brake Master Cylinder is mounted to it) stores vacuum. A check-valve in the vacuum line from engine to Booster keeps vacuum in the booster when engine vacuum drops. The Booster stores about 2 1/2 brake applications worth of vacuum.

You can test this, and it's worth the lesson. With car in Park, engine running and foot NOT on brake, turn off engine. Then press down on brake pedal a good amount. Pedal will move down, signifying vacuum boosting of your effort. That was application #1. Then take foot off of brake, then re-apply. Pedal moves easily down again, that's #2. Foot off of brake again, then re-apply. This time, the pedal will start to go down, then get as hard as a rock.
That hard-as-a-rock feel is the direct mechanical linkage path from pedal through booster to Master Cylinder, without the vacuum boosting effect.
This is important to know, because it means if the engine should quit while you are driving, don't pump the brakes, or your 2 1/2 times will be used up! Instead, apply brake increasingly firm to find a spot to stop.
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Old 11-05-2009, 06:47 AM   #34
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Where do you live-Bonneville?

This whole thing reminds me of MORE reasons to love my ancient rice burner:
- No electronic speed controls to go crazy
- A manual transmission that makes it simple and intuitive to isolate the engine from the rest of the drivetrain.
- A puny motor that could easily be reigned in by my brakes.
- An engine that would helpfully throw a rod at engine speeds above 6000 rpm
- An inability to achieve 120 MPH even downhill and with a hurricane gale from the rear.
Maybe my post was not clear but this was clearly a driver error. The off duty chp as a trained safety inspector have plenty of time to correct the problem.

1. applying the brakes
2. shifting to neutral
3. turn the engine off

If I was going downhill that fast I would worry and try to fix the problem. Plus the vehicle is a loaner car so my main concern would be the safety of all the person in the vehicle rather than worry about blowing up the car. I will make sure I do everything to stop the car. This guy called 911. What was he thinking?
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Old 11-05-2009, 07:41 AM   #35
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Maybe my post was not clear but this was clearly a driver error. The off duty chp as a trained safety inspector have plenty of time to correct the problem.

1. applying the brakes
2. shifting to neutral
3. turn the engine off

If I was going downhill that fast I would worry and try to fix the problem. Plus the vehicle is a loaner car so my main concern would be the safety of all the person in the vehicle rather than worry about blowing up the car. I will make sure I do everything to stop the car. This guy called 911. What was he thinking?
There are very few of us who would have taken the time necessary to learn all of the fine points about the loaner car we were given at the dealer's garage. Unfortunately, cars have gotten complicated enough that operating them is no longer intuitive. This event has also given the drive-by-wire design guys something to add to their programming: cut to idle when braking. That seems like it would work all the time, since it is how the cruise control works.
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Old 11-05-2009, 11:01 AM   #36
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.... This guy called 911. What was he thinking?
The driver did not, as I read it, his SIL in the back seat did.
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Old 11-05-2009, 11:16 AM   #37
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Originally Posted by steve88 View Post
Maybe my post was not clear but this was clearly a driver error. The off duty chp as a trained safety inspector have plenty of time to correct the problem.

1. applying the brakes
2. shifting to neutral
3. turn the engine off

If I was going downhill that fast I would worry and try to fix the problem. Plus the vehicle is a loaner car so my main concern would be the safety of all the person in the vehicle rather than worry about blowing up the car. I will make sure I do everything to stop the car. This guy called 911. What was he thinking?
Well, as I pointed out in an earlier post, the LA Times looked at the wreck in more detail and accounted for probable difficulties the driver may have encountered:

Quote:
The Lexus sedan was equipped with an automatic transmission control that mimics old-fashioned manual shifters, making it difficult for a driver to shift to neutral while the car is moving.

The power assist brakes rely on a vacuum that diminishes as the engine revs faster, reducing the braking assistance to near zero if the engine is roaring.

The manual brakes are unable to stop a 272-horsepower engine getting an open throttle and moving 120 mph. [Duh, really?]

The keyless ignition system requires a driver to hold a dashboard button down for three seconds to turn the engine off, a fact that is disclosed in the vehicle manual but may not be obvious to a motorist.

And perhaps most-damning, the car's computers do not reduce gas flow to the engine when the brakes are applied.
When I was reading about this the other day I remember a quote from a witness that the brakes were on fire at some point before the wreck.
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Old 11-05-2009, 11:51 AM   #38
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You are absolutely right. The Bil was the one that made the phone call.
My sister has a lexus similar engine to this guy suv loaner. The car does not accelerate from 50 to 120mph in a split second. It took a long time to accelerate from 50 mph to 120. The distance traveled before it hit 120 mph was quite a distance. I forgot to check the mileage distant on that. I will do it again today.

The family was travelling on a surface street and the speed limit was 45-50mph. I would be really worried if my car was travelling 80 mph on a surface street. When our car reached 90 mph it was hair raising but we kept going until it reached 120 mph.
I believe there was so much time to fix the problem. He could have also downshifted to d1 assuming he tried neutral but did not work. D1 is almost the same as 1st gear. I rather ruin the car as oppose to the other outcome.

I am not defending toyota but I just wonder how a person with that background and where it happened resulted to this catastrophic accident. I just can't imagine myself driving and my car suddenly accelerate, without me stepping on the accelerator ,just wait for the car to slow down. Especially on a surface street.
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Old 11-05-2009, 03:03 PM   #39
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I am one who also said to downshift to 1st... but I also know that some transmissions will NOT allow this to protect them from damage... I would bet that Lexus has this feature...


I would bet that Toyota will lose the lawsuit that will be filed...
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Old 11-05-2009, 04:41 PM   #40
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I get it, Steve. You did a test, and you think you could have done better. The experts have explained the extenuating circumstances and some real issues that make this case more complex than most people would have thought, but you think you could have done better.

I don't think the people inthe car were just sitting around and playing Parcheesi while the car was accelerating, I'll bet the driver was plenty motivated to take appropriate actions. We've identified a lot of the "common sense" appropriate actions, and why they wouldn't work (or at least not work in a manner we would expect).

They are all dead. It's not clear what you want.

Please don't drive 120 MPH on some public road doing more "tests." It is dumb.
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