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Toyota Recall 2
5

Toyota Recall 2

Toyota Recall 2

(OP)
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.

RE: Toyota Recall 2

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.

RE: Toyota Recall 2

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

RE: Toyota Recall 2

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!

 

RE: Toyota Recall 2

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.

RE: Toyota Recall 2

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.
 

RE: Toyota Recall 2

If there is a technical issue by all means it should be identified and corrected. What I want to know is how people who don't know how to apply the brakes, shift into neutral or shut off the ignition - get a driver's license?

RE: Toyota Recall 2

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  

RE: Toyota Recall 2

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.

RE: Toyota Recall 2

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

RE: Toyota Recall 2

It's the Aliens! ET has taken control!

RE: Toyota Recall 2

(OP)
exactly......wow people these days.......

RE: Toyota Recall 2

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.

RE: Toyota Recall 2

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.

 

RE: Toyota Recall 2

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!

RE: Toyota Recall 2

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.
 

RE: Toyota Recall 2

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.

RE: Toyota Recall 2

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

RE: Toyota Recall 2

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!

http://www.youtube.com/watch?v=lZ4PtafRB9c&feature=player_embedded

RE: Toyota Recall 2

Tsk Tsk... he said "retard"

RE: Toyota Recall 2

Quote:

Tsk Tsk... he said "retard"

Wasn't the whole point about slowing the car to a stop?

RE: Toyota Recall 2

I don't doubt that Audi issued a recall.

Audi also installed vacuum pumps to ensure that the brake booster absolutely, positively never lost vacuum.  And then, they went to hydraulic brake assist.

As far as control is concerned, it works on the same principle as the Ford units.

 

RE: Toyota Recall 2

One outcome of the Audi SUA witchhunt was that we had to fit interlocks, such that you could only start the engine if the T bar was in P or N, and your foot was on the brake.

Not the end of the world, but you the consumer ended up paying 10-50 bucks per car for that.

 

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies  http://eng-tips.com/market.cfm?

RE: Toyota Recall 2

Better plan for more, Greg.  I'm guessing the Toyota deal will add a few more bucks in "master shutoff"...

Rod

RE: Toyota Recall 2

Cars already have a master shut-off. It's called the ignition switch... <LOL>

RE: Toyota Recall 2

That's not a master shutoff, it's just a request switch.  It's still up to the electronics to decide if and when to shut things off.

You cannot cure human ignorance through technology.  I have known people who were not aware that you could manually unlock a door in a power lock equipped car.

 

RE: Toyota Recall 2

Maybe we could place the battery in the passenger seat with a quick release so the driver could toss it out the window when their car has "unintended acceleration"? Would that be a master cut-off is has Satan taken over control of these cars? <LOL>

RE: Toyota Recall 2

These electronic throttle pedal have been used for a long time on VW and Audi cars. In fact, all Volkswagen equipped with a TDI (diesel engine) are using this setup since more than 10 years.

RE: Toyota Recall 2

Would that be a master cut-off is has Satan taken over control of these cars?
jettisoning the batteries might work, but you'd also have to add an indicator light or flashing (up/down) arrow to show whether it was satan or the lord who had control... wouldn't want to inadvertently interrupt a miracle.
 

RE: Toyota Recall 2

As mentioned above VW/Audi have been using FBW throttle on their TDIs for years.  My '96 A6 has one but they have been around since '93, possibly a year so longer.  They don't fail often, but when they do you get a car that will idle but nothing more.  Mine has 203K miles without issues so far.
Pressing brake and throttle together does not cut the throttle, or at least not for several seconds - I'll have to do some more trials to see if anything happens if you persist.  As the car is manual with a conventional ignition key, stopping shouldn't be an issue in any case.

Nick

RE: Toyota Recall 2

That's the "key", Nick...(pardon the pun)!

Rod

RE: Toyota Recall 2

The VW/Audi system in my car will cut throttle immediately if you are on the accelerator pedal first and THEN step on the brake. It will allow the accelerator pedal input if you are on the brake first and then step on the accelerator; this is to allow heel/toe downshifting.

Here's the odd thing; despite the accelerator/brake interlock, VW/Audi are not excluded from "sudden acceleration" reports to NHTSA. It still happens to them. Operator error ...

RE: Toyota Recall 2

Sundays paper said the rate of reported uncontrolled acceleration problems has gone up 20 fold since the first of the year.  Prius brake problem reports have go up much faster.  Sounds like a mass hysteria to me.

RE: Toyota Recall 2

In 1988, I was asked to test a Volvo that was supposed to exhibit the same problem, the engine overruning the brakes.  In every case, I was able to bring the car to a stop (simutaneous application of brake and throttle in 10 mph increments from idle to 100 mph.)  At higher speeds, I encountered brake fade but I was still able to control the vehicle.
The Volvo did have a mechanical throttle link (cable actuated).
I believe Ford recently did a study on their high performance Mustang and found that they could control it as well, and the Mustang has several times the wheel horsepower as the Camry or Prius.
Franz

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Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.
 

RE: Toyota Recall 2

Now officials are starting to wonder what I wondered last week... Did the 94 mph Prius driver in CA create the situation to get media attention? They've inspected the vehicle and find nothing wrong with it. It has an over-ride so that when you apply the throttle and brakes it returns to idle - and it functions. According to engineers the electric motor would seize if what the driver reported actually happened, yet there is no seizure.

There appears to be nothing wrong with the vehicle and the brakes were not burned out and function fine. You would expect the brakes to be burned up if the driver was actually trying to stop over the long distance that he traveled.

It's impossible to prove the incident was staged, isn't it?

RE: Toyota Recall 2

Saw the San Diego Prius guy on TV with his mouthpiece, squealing "No lawsuit is planned"!!

Heard the 911 operator several times suggesting knocking trans into neutral.

He says "I'm trying to control the car"  (while talking on a cell phone)

This has 'balloon boy' part 2 all over it.

Neighbors and friends (?) say he's a grifter & BS artist.

RE: Toyota Recall 2

When Audi was going through the unintended acceleration debacle, they were 11th on the list of complaints. GM was number one. A California newspaper reports that one of the Prius complaint ants had just files for bankruptcy & was $700,000 in debt. The car had no brake pad material left on the front brakes.

RE: Toyota Recall 2

Great video. That needed to be said. I'm also tired of running over these things & Smart Cars in the left lane

RE: Toyota Recall 2

You must not live in SoCal....The traffic on the I 15 averages about 80 and the Prius things along with the crazies in the Smart for Two's run right along with them.  Even the trucks in the "slow" lane are usually well over the speed limit.  Only time I have any difficulty with them is climbing the hills going down to San Diego.

Rod

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