I have read the previous question involving the Toyota recall and there was more things i was wondering about this incident. There is alot of talk about a "drive by wire" system.How does this system work? I also heard that Audi had the same problem about 20 years ago. What happened in that situation? Thank you for answering.
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Toyota Recall 2 5
- Thread starter bob9250
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Drive by wire, in this circumstance, just means that the accelerator does not mechanically control the throttle plate. The accelerator provides an electronic position signal to the ECM which then decides, based on accelerator position and other factors, what the appropriate engine load should be.
Since the driver does not mechanically control the throttle, there is a feeling among some that a final driver veto on the system is missing. However, given that mechanical linkages can break (and more often than electronics), there is a feeling among others that drive-by-wire is just as safe, although it does depend on having a good design in the electronics and software.
Don't know which Audi thing you're talking about, so I'll leave that part to others.
Since the driver does not mechanically control the throttle, there is a feeling among some that a final driver veto on the system is missing. However, given that mechanical linkages can break (and more often than electronics), there is a feeling among others that drive-by-wire is just as safe, although it does depend on having a good design in the electronics and software.
Don't know which Audi thing you're talking about, so I'll leave that part to others.
The Audi deal is still not resolved. My opinion is that the drivers hit the brakes AND the accelerator at the same time. None the less, lots of lawyers got rich.
The throttles and transmissions of the cars in question are controlled "by wire". No direct mechanical connection from the pedal or gear shift lever to anything.
To some of us oldtimers, that brings the electronics into question...especially everytime I must reboot this PC...
I really like direct control over my vehicle. Since most of my vehicles are either classics or antiques, that's not a problem. The wife's Lincoln is all DBW and, after nine years and 170k miles it has not been a problem. Perhaps I really am TOO old.
One thing mentioned...broken mechanical linkage. Hmmmm. In well over 50 years of driving, street and race, I've had ONE throttle failure and that was in the early 80's in a race car...the throttle cable came out of it's "detent"...My fault since I built it wrong.
Rod
The throttles and transmissions of the cars in question are controlled "by wire". No direct mechanical connection from the pedal or gear shift lever to anything.
To some of us oldtimers, that brings the electronics into question...especially everytime I must reboot this PC...
I really like direct control over my vehicle. Since most of my vehicles are either classics or antiques, that's not a problem. The wife's Lincoln is all DBW and, after nine years and 170k miles it has not been a problem. Perhaps I really am TOO old.
One thing mentioned...broken mechanical linkage. Hmmmm. In well over 50 years of driving, street and race, I've had ONE throttle failure and that was in the early 80's in a race car...the throttle cable came out of it's "detent"...My fault since I built it wrong.
Rod
I own an Audi product of that era, and when cold the throttle does feel odd. There is a higher resistance than normal to the throttle pedal, like the throttle blades are offset a little too much. (It's nothing at all like a sticky throttle due to carbon)
The story, as related to me, was that people would rest their foot on the throttle pedal thinking it was the brake. Then, they'd shift into gear, and the car would start moving. Then they'd push the "brake" harder. Voom!
The story, as related to me, was that people would rest their foot on the throttle pedal thinking it was the brake. Then, they'd shift into gear, and the car would start moving. Then they'd push the "brake" harder. Voom!
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BrianPetersen
Mechanical
Should note that the Audi vehicles that were the subject of the original "sudden acceleration" were not drive-by-wire. They used the Bosch mechanical CIS fuel injection system, as did most VW/Audi gasoline engines of that era.
Also, maybe the auto designers should have a look at how Yamaha did the drive-by-wire throttles on the current and prior R6 motorcycle. The computer takes an input from a sensor and positions the throttle, but there is also a mechanical linkage from the rider's throttle to the actual throttle mechanism at the engine. The computer is capable of opening the throttles *up to* the amount that the rider requests, but never more. That way, if the rider closes the throttle, the throttle closes, no matter what the computer thinks.
Presumably, full electronic control was not considered to be fail-safe enough for a motorcycle with 100-plus horsepower weighing less than 400 lbs.
Also, maybe the auto designers should have a look at how Yamaha did the drive-by-wire throttles on the current and prior R6 motorcycle. The computer takes an input from a sensor and positions the throttle, but there is also a mechanical linkage from the rider's throttle to the actual throttle mechanism at the engine. The computer is capable of opening the throttles *up to* the amount that the rider requests, but never more. That way, if the rider closes the throttle, the throttle closes, no matter what the computer thinks.
Presumably, full electronic control was not considered to be fail-safe enough for a motorcycle with 100-plus horsepower weighing less than 400 lbs.
LionelHutz
Electrical
From what I've read, Audi did replace the idle controllers in many or all of those cars. My theory, partly from what I've read, is that the idle controller was a magnet and coil with electronics that applied a current in the coil to move the controller to the position it wanted, probably pulling against a spring, so that more current opened the controller further. There would likely also be a PI type feedback controller for the idle speed, likely using engine rpm as the input and idle controller current as the output. If the controller stuck, then the integrator would wind up until it popped loose. This would likely have the result of pulling the controller full open. It could also take some time to close again depending on how much the integrator wound up. You can guess when the controller would need to suddenly increase the engine rpm - right when the car is shifted into drive which causes a sudden drop in idle rpm.
I've really only played with the stepper motor idle control valves and they wouldn't react this same way since they really can't move faster than their operating speed. Also, a sticking stepper type typically just won't turn anymore. The electronics can't apply a stronger signal until they break it loose.
Detailed info on the internet is hard to find for the Audi case and I didn't come across anything with enough detail to fully describe what was going on with the idle controllers.
I've really only played with the stepper motor idle control valves and they wouldn't react this same way since they really can't move faster than their operating speed. Also, a sticking stepper type typically just won't turn anymore. The electronics can't apply a stronger signal until they break it loose.
Detailed info on the internet is hard to find for the Audi case and I didn't come across anything with enough detail to fully describe what was going on with the idle controllers.
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To illustrate JSteves point, I had a '72 VW beetle with "drive by wire" problems. The throttle cable slipped out of bracket at the throttle after I accelerated to pass and stuck full open (Interesting default position, in my book). Traffic was heavy, with no shoulder and a long stretch until I had a side street. Even better, it was a left-hand drive in the UK. I used on/off and second gear for speed limitation. On the plus side, I didn't need any ohter diagnostic tool than my eyes to determine the fault
I assume your "DBW" comment on the '72 VW is a joke as DBW didn't exist on VW's back then. No auto maker has a default throttle position that is WOT either. I guess the intent of your comment is to show that driving skills should be a requirement before people are issued a driver's license. Anything less is a danger to society.
With the current revelation that some 250 Prius complaints have been about speed control...last evenings news...I'm left to ponder whether we are a nation of complete idiots or just being taken advantage of by a few "Madoff" types?
As regards the old Audi deal...That scandal left us with three things. One, it issued in the era of the "recall". Two, it brought us the brake pedal override so you cannot shift into drive without pedal pressure. Three, it has created an "industry" of attorneys that exist solely for the purpose of making said "idiots" rich.
For standard shift cars, they got the stupid switch so you had to depress the clutch pedal to start. It was such a good idea that the auto industry abandoned that idea in the late 30's (E.g., 1937 Nash Ambassador with starter button under the clutch pedal and activated by the depressed pedal).
Shucks, I must be crazy to ride my '48 Norton without a little green light to tell me when it is in neutral!!!
Rod
As regards the old Audi deal...That scandal left us with three things. One, it issued in the era of the "recall". Two, it brought us the brake pedal override so you cannot shift into drive without pedal pressure. Three, it has created an "industry" of attorneys that exist solely for the purpose of making said "idiots" rich.
For standard shift cars, they got the stupid switch so you had to depress the clutch pedal to start. It was such a good idea that the auto industry abandoned that idea in the late 30's (E.g., 1937 Nash Ambassador with starter button under the clutch pedal and activated by the depressed pedal).
Shucks, I must be crazy to ride my '48 Norton without a little green light to tell me when it is in neutral!!!
Rod
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I was driving my 79 Mustang home from a bar (perhaps with less than full control of my faculties) when the choke mechanism came loose from the carb and jammed the throttle open about 50%. I managed to drive through town (couple of traffic lights and turns) using a combination of switching the ignition on & off, clutching, braking etc. to my house where I drove it over the curb & shut it down in the front yard. I did not sue the manufacture.
The Audi idle control valves of 20 years ago did not actuate the throttle valve, only a small idle air bypass circuit. Wide open on that circuit the engine could not have made more than about 15 HP, if that. Sure, it could have slowly increased the vehicle speed but not cause it to leap from a standing start through block walls like some people tried to claim.
When you have just run some one over or had some other tragic accident, the mind refuses to believe it could be your fault and will come up with all manner of impossible excuses for what happened.
The Audi idle control valves of 20 years ago did not actuate the throttle valve, only a small idle air bypass circuit. Wide open on that circuit the engine could not have made more than about 15 HP, if that. Sure, it could have slowly increased the vehicle speed but not cause it to leap from a standing start through block walls like some people tried to claim.
When you have just run some one over or had some other tragic accident, the mind refuses to believe it could be your fault and will come up with all manner of impossible excuses for what happened.
The Audi idle air motor is a generic Bosch part, still in use by Hyundai as of the mid-2000s. It defaults to roughly 1/4-open, probably specifically to prevent it sticking shut. With the motor fully closed, there will be insufficient airflow through the throttle plate to allow a full warmed engine to idle.
Fully open can move a lot of air relative to a regular idle control motor, but it's still not going to be anywhere near enough to overpower the brakes.
Fully open can move a lot of air relative to a regular idle control motor, but it's still not going to be anywhere near enough to overpower the brakes.
DBW problems and control protocols need quick, decisive action, since our fine elected officials have deemed electronic stability programs need to be mandatory standard equipment in '12... Limited in effectiveness without throttle control as part of the package. GM used a traction control system that used a cable in the '90's, tho. Pretty spooky to have the throttle push your foot back on loss of traction!
LionelHutz
Electrical
I never said the Audi idle controller would cause the level of runaway that some people claimed happened or that it would open the main throttle plates, but it would certainly cause more than a 15hp power surge. If it opened suddenly, it would be enough to startle people and enough to move the car before some drivers would realize they need to hit the brakes harder than they normally do when sitting stopped and in drive.
If it's anything like the GM systems I've played with then I'd bet it'd produce the same results as what is required to run the engine >3000rpm in neutral. I'd think you'd be really concerned for your engine if a GM idle control valve stuck wide open. Even at about 30% it would be running the engine around 2500rpm.
Does anyone have the details on how the Audi idle controller motor is built and controlled?
We all know Audi would not come out and openly make a big deal about it being the problem, but they issued a safety recall for the thing as part of the solution to the sudden acceleration issue so Audi must have figured it was partly to blame.
If it's anything like the GM systems I've played with then I'd bet it'd produce the same results as what is required to run the engine >3000rpm in neutral. I'd think you'd be really concerned for your engine if a GM idle control valve stuck wide open. Even at about 30% it would be running the engine around 2500rpm.
Does anyone have the details on how the Audi idle controller motor is built and controlled?
We all know Audi would not come out and openly make a big deal about it being the problem, but they issued a safety recall for the thing as part of the solution to the sudden acceleration issue so Audi must have figured it was partly to blame.
TrackRat,
Yes, a joke. As far as the Fail WOT, it was thirty years ago that this happened, and my memory isn't what it used to be, but, I was somewhat conversant with control systms and remember thinkng to myself that it was an odd way to work it. Beetles had all sorts of interesting ideas, among them, gas (petrol) auxilliary heaters, using the spare to provide pressure for the window washer, the battery under the back seat, which would occasionally short out, etc. I could be, and, too often am, wrong though.
My main point is that mechanical systems are not fool proof either.
Yes, a joke. As far as the Fail WOT, it was thirty years ago that this happened, and my memory isn't what it used to be, but, I was somewhat conversant with control systms and remember thinkng to myself that it was an odd way to work it. Beetles had all sorts of interesting ideas, among them, gas (petrol) auxilliary heaters, using the spare to provide pressure for the window washer, the battery under the back seat, which would occasionally short out, etc. I could be, and, too often am, wrong though.
My main point is that mechanical systems are not fool proof either.
The old joke is that "you can make it fool proof, but not idiot proof" as I recall. Problems arise when you put non automotive types (idiots, if you will) in charge of the design criteria and specifications.
Truth. ALL mechanical and electronic control systems CAN and, often do, fail. With the old cable throttle failure was generally to the idle position. When you selected "N" in the trans, you GOT neutral. Point is, yes, mechanical systems CAN FAIL but, in light of over 100 years of history, not as often as the new computer controlled system. At least that's the way it seems with a "zillion" more cars on the road.
I'm not your regular car guy. I'm an old racer. With most newer cars I don't get to choose, but I do not like Trac control, ABS, DBW, SBW, I'm not too crazy about automatic transmissions. My wife's car has all these things and more...therefore, I DON'T GET A CHOICE! If you get my drift.
Rod
Truth. ALL mechanical and electronic control systems CAN and, often do, fail. With the old cable throttle failure was generally to the idle position. When you selected "N" in the trans, you GOT neutral. Point is, yes, mechanical systems CAN FAIL but, in light of over 100 years of history, not as often as the new computer controlled system. At least that's the way it seems with a "zillion" more cars on the road.
I'm not your regular car guy. I'm an old racer. With most newer cars I don't get to choose, but I do not like Trac control, ABS, DBW, SBW, I'm not too crazy about automatic transmissions. My wife's car has all these things and more...therefore, I DON'T GET A CHOICE! If you get my drift.
Rod
Any DBW system that I have seen always reverts to idle when signal inputs don't match or any other malfunction occurs. In otherwords garbage in = no go, no where.
There is a funny video with some foul language on YouFool, I mean YouTube... where a guy in a ski mask for obvious reasons, shows that if you shift the Prius into neutral it rolls to a stop. He also shows that shuting off the ignition amazingly stops the car. Basically as a Prius owner he tales offense at people of questionable driving skills making other Toyota owners look like incompetent idiots. His point however about the Prius being fully controllable by the driver even if there were sudden acceleration is valid.
Warning -- Don't play the video if you're offended by blue language!
There is a funny video with some foul language on YouFool, I mean YouTube... where a guy in a ski mask for obvious reasons, shows that if you shift the Prius into neutral it rolls to a stop. He also shows that shuting off the ignition amazingly stops the car. Basically as a Prius owner he tales offense at people of questionable driving skills making other Toyota owners look like incompetent idiots. His point however about the Prius being fully controllable by the driver even if there were sudden acceleration is valid.
Warning -- Don't play the video if you're offended by blue language!
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