OT: the Toyota Deal Options

[ghuff]

As can be seen here, the outputs of the potentiometers are identical but for an offset. Cars equipped with automatic transmissions do not have an additional kickdown switch in the assembly; instead a 'mechanical pressure point' is used to give the feel of a kickdown switch.

(IMG:http://img256.imageshack.us/img256/4420/1083796mgwi4.jpg)

In the event that the accelerator position sensor fails, the lack of any mechanical connection between the accelerator and the throttle blade requires that sophisticated 'limp home' techniques are in place. The Audi S4 uses two techniques:
Emergency running program #1

This occurs when a single accelerator position potentiometer fails.

* Throttle position is limited to a defined value;
* In the case of implausible signals from the two potentiometers, the lower value of the two is used;
* The brake light signal is used to indicate when idling speed should be enacted;
* The fault lamp is illuminated.

Emergency running program #2

This occurs when both accelerator position potentiometers fail.

* The engine runs only at idle speed;
* The fault lamp is illuminated.

Interestingly, if in the Audi the accelerator and brake pedals are depressed together, the throttle valve is automatically closed to a defined small opening. However, if the brake is pressed and depressing of the accelerator then follows this, the torque request is enabled. I assume that the latter provision is solely for those who like to left-foot brake, with applications of power used to balance the car!

[ghuff]

(IMG:http://img128.imageshack.us/img128/2355/1083797mgxn6.jpg)

The Audi S4 electronic throttle valve consists of a DC motor, reduction gear drive and dual feedback angle sensors. It is again for reasons of redundancy that two potentiometers are used for angle feedback. However, unlike the accelerator position sensor, these sensors have opposite resistance characteristics to one another, as shown below.

(IMG:http://us1.webpublications.com.au/static/images/articles/i1083/108379_8mg.jpg)

While continuous sensing of throttle blade position does occur, the ECU recognises four key functional positions of the throttle blade:

* Lower mechanical limit stop - the valve is totally shut.
* Lower electrical limit stop - the lower limit used in normal operation. This position does not totally close the valve, thus preventing contact wear of the housing and throttle blade.
* Emergency running position - the position of the valve when it is not energised. This allows sufficient airflow for an idle speed a little higher than standard.
* Upper electrical limit stop - the blade is fully open.

The control system has a self-learning function, whereby the state of the mechanicals within the electronic throttle (eg spring tensions) is determined by the evaluation of the throttle valve's reaction speed.

As with the Accelerator Pedal Position Sensor, sophisticated limp-home techniques are available should the Electronic Throttle Control Actuator develop problems. These include:
Emergency running program #1

This occurs when an angle sensor within the throttle body fails or an implausible signal is received. Required is an intact throttle angle sensor and plausible mass airflow measurement.

* Torque increasing requests from other systems are ignored (eg from the Engine Braking Control);
* The fault lamp is illuminated.

Emergency running program #2

This occurs if the throttle valve drive fails or malfunctions; it requires that both throttle valve potentiometers recognize the Emergency Running Position of the throttle blade.

* The throttle valve drive is switched off so that the valve defaults to the small emergency running opening;
* As far as possible, ignition angle control and turbo boost control(!) are used to execute driver torque demands.
* The fault lamp is illuminated.

Emergency running program #3

This occurs if the throttle valve position is unknown and/or if the throttle valve is not definitely known to be in the Emergency Running Position.

* The throttle valve drive is switched off so that the valve (hopefully!) defaults to the small emergency running opening;
* The engine speed is limited to approximately 1200 rpm by fuel injection control;
* The fault lamp is illuminated.

An Audi schematic diagram showing the operation of the electronic throttle system is shown here.

(IMG:http://img398.imageshack.us/img398/4645/1083799mgcj2.jpg)

As you can see, Bosch engineers have been very careful to ensure that a failure of the electronic throttle system will not cause the car to suddenly have full power - or a stalled engine.




I will stick with my bosch electronics, what fails does not kill me and usually is just annoying.

[Katmanken]

Apparently the pedal assembliesare made by CTS inustries, Elkhart IN to Toyota specifications.

And they claimed that there are fewer than a dozen instances of locked full throttle.

Wonder if they used the MIL-P-FP rule, (make it like the frickin print) or the "build to spec" rule. If it's build to spec, then it's gonna be built a little differently than a Toyota design. Interesting to see who is at fault.

From my experience with fixing problems, many times a "cost improvement" was involved.

[sixaddict]

HAve a 05 Avalon.......94K miles ...Never an issue although that may not mean a thing. Stuck throttles are always a shock and test your ability to react..Mine was at Alameda cty fair ground in a autocross heading for the finish line and all the spectators. Clutch in oops kill the engine. BUt......can't image the accelation needed to get to 95 before even I could react.
TOT

[FourBlades]

Just bring a big anchor with you and tie it to the rear axle.

Car goes crazy, throw out the anchor.

John

[richardL]

I'm curious as to what happened in the case of that police officer in San Diego not being able to bring his car to a stop and subsequently killing himself and his family? Some sort of (computer) system malfunction that affected those things that I could use to shut down my wife's car?

Andys

From what I have read it was a loaner car with a keyless entry and ignition. To turn the engine off you have to press and hold the Start button for 3 seconds - since it wasn't his car, he didn't know that, or couldn't do it in the panic. It was also stated that it was difficult to shift into neutral while moving (don't know why) and that his brakes were on fire by the time he crashed, trying to slow it down. :-(

[zymurgist]

It was also stated that it was difficult to shift into neutral while moving (don't know why)

No mechanical connection between the shifter and the transmission, perhaps?

[Cap'n Krusty]

I would bet that 60 minutes will barely touch this story.

For some reason, they had a burr up thier ass for Audi in the early 90's, but I would bet they give Toyota a pass. Came close to putting Audi out of business.

Well see. But "journalists" set their own priorities, Asshats!

The Audi "un-intended accelleration" was for real from my own eye witness: my neighbor damned near ran his wife over in his driveway when said Audi decided it wanted to suddenly take off. It was real scarey, to be sure.

Ok, so I tested my wife's '10 Camry just now. Driving with the gas pedal depressed I can shift from drive to neutral and the engine will race as expected (did this five times). Also while driving I simply switched the ignition off (obviously not into the lock position) and the engine shut down. The car was not difficult to steer, and the booster reservoir had plenty reserve to bring the car to an assisted stop. I'm curious as to what happened in the case of that police officer in San Diego not being able to bring his car to a stop and subsequently killing himself and his family? Some sort of (computer) system malfunction that affected those things that I could use to shut down my wife's car?

Andys

Studies by independent and government automotive research organizations in several countries have found NOT A SINGLE incident where the car was at fault in the so-called "unintended acceleration" scare involving, among others, Audi (you probably never heard of the others). NOT ONE. Every single reported case was thoroughly investigated by organizations other than Audi, and Audi (along with the other manufacturers involved) was 100% absolved. Never heard about that, either, right? Audi had every right, and the legal grounds, to sue CBS a*s off, but chose not to do so. Might have been a bad thing to drive a TV network off the air, right? Or maybe they should have, considering the disaster TV is today. IIRC, BTW, not a single claim made it through the courts.

The Cap'n

[andys]

I would bet that 60 minutes will barely touch this story.

For some reason, they had a burr up thier ass for Audi in the early 90's, but I would bet they give Toyota a pass. Came close to putting Audi out of business.

Well see. But "journalists" set their own priorities, Asshats!

The Audi "un-intended accelleration" was for real from my own eye witness: my neighbor damned near ran his wife over in his driveway when said Audi decided it wanted to suddenly take off. It was real scarey, to be sure.

Ok, so I tested my wife's '10 Camry just now. Driving with the gas pedal depressed I can shift from drive to neutral and the engine will race as expected (did this five times). Also while driving I simply switched the ignition off (obviously not into the lock position) and the engine shut down. The car was not difficult to steer, and the booster reservoir had plenty reserve to bring the car to an assisted stop. I'm curious as to what happened in the case of that police officer in San Diego not being able to bring his car to a stop and subsequently killing himself and his family? Some sort of (computer) system malfunction that affected those things that I could use to shut down my wife's car?

Andys

Studies by independent and government automotive research organizations in several countries have found NOT A SINGLE incident where the car was at fault in the so-called "unintended acceleration" scare involving, among others, Audi (you probably never heard of the others). NOT ONE. Every single reported case was thoroughly investigated by organizations other than Audi, and Audi (along with the other manufacturers involved) was 100% absolved. Never heard about that, either, right? Audi had every right, and the legal grounds, to sue CBS a*s off, but chose not to do so. Might have been a bad thing to drive a TV network off the air, right? Or maybe they should have, considering the disaster TV is today. IIRC, BTW, not a single claim made it through the courts.

The Cap'n

Believe me Cap'n, I was one of those skeptics with the whole Audi "un-intended accelleration" deal until I saw it happen with my own eyes. The person involved was a car guy; Bio= vehicle designer/stylist, race car designer (CanAm winner), Art Center instructor in vehicle design, and more than I can post in short. I also did a couple of vehicle projects with him; PM me if you're interested. Anyway, Audi factory sent a Rep to his home, and purchased the car from him on the spot and trailered it away. Though that initself is not an admission of a problem, I suspect (as my neighbor speculated) Audi wanted to do a complete evaluation of a known occurance. He never heard from Audi after that, that I'm aware of.

None of the above however, would not keep me from considering an Audi purchase. I suspect there are "others" like in my '73 Vette experience that goes either un-reported or flys under the radar.

Andys

[aircooledtechguy]

And my family wonders why I don't bother with "new" cars. . . Things have just gotten needlessly over complicated to keep folks going to the dealers for maint. That's crap!!

[patssle]

Reason #23963 to drive a stick?

Can't wait for the day that clutches become electronic too.

[ws91420]

Just remembered their old slogan. Oh what feeling Toyota !

[0396]

(IMG:http://img128.imageshack.us/img128/2355/1083797mgxn6.jpg)

The Audi S4 electronic throttle valve consists of a DC motor, reduction gear drive and dual feedback angle sensors. It is again for reasons of redundancy that two potentiometers are used for angle feedback. However, unlike the accelerator position sensor, these sensors have opposite resistance characteristics to one another, as shown below.

(IMG:http://us1.webpublications.com.au/static/images/articles/i1083/108379_8mg.jpg)

While continuous sensing of throttle blade position does occur, the ECU recognises four key functional positions of the throttle blade:

* Lower mechanical limit stop - the valve is totally shut.
* Lower electrical limit stop - the lower limit used in normal operation. This position does not totally close the valve, thus preventing contact wear of the housing and throttle blade.
* Emergency running position - the position of the valve when it is not energised. This allows sufficient airflow for an idle speed a little higher than standard.
* Upper electrical limit stop - the blade is fully open.

The control system has a self-learning function, whereby the state of the mechanicals within the electronic throttle (eg spring tensions) is determined by the evaluation of the throttle valve's reaction speed.

As with the Accelerator Pedal Position Sensor, sophisticated limp-home techniques are available should the Electronic Throttle Control Actuator develop problems. These include:
Emergency running program #1

This occurs when an angle sensor within the throttle body fails or an implausible signal is received. Required is an intact throttle angle sensor and plausible mass airflow measurement.

* Torque increasing requests from other systems are ignored (eg from the Engine Braking Control);
* The fault lamp is illuminated.

Emergency running program #2

This occurs if the throttle valve drive fails or malfunctions; it requires that both throttle valve potentiometers recognize the Emergency Running Position of the throttle blade.

* The throttle valve drive is switched off so that the valve defaults to the small emergency running opening;
* As far as possible, ignition angle control and turbo boost control(!) are used to execute driver torque demands.
* The fault lamp is illuminated.

Emergency running program #3

This occurs if the throttle valve position is unknown and/or if the throttle valve is not definitely known to be in the Emergency Running Position.

* The throttle valve drive is switched off so that the valve (hopefully!) defaults to the small emergency running opening;
* The engine speed is limited to approximately 1200 rpm by fuel injection control;
* The fault lamp is illuminated.

An Audi schematic diagram showing the operation of the electronic throttle system is shown here.

(IMG:http://img398.imageshack.us/img398/4645/1083799mgcj2.jpg)

As you can see, Bosch engineers have been very careful to ensure that a failure of the electronic throttle system will not cause the car to suddenly have full power - or a stalled engine.




I will stick with my bosch electronics, what fails does not kill me and usually is just annoying.

Thanks for the education...now you should also post thin on the Audi boards too.

[championgt1]

Just remembered their old slogan. Oh what feeling Toyota !

(IMG:style_emoticons/default/lol-2.gif)

[DBCooper]

Substitute goodness, gracious "Great Balls of Fire" for "My Brakes are on Fire!".

[grantsfo]

My $.02... I'll bet the variable resister or what ever signals the computer comes from China.

I have been thinking same thing. Part may have been assembled here, but I bet fualty component came from some crack pot manufacturing floor in China. Being involved in manufacturing over there I see crappy quality in components made there all the time.

When are good companies going to realize you cant shortcut quality on critical systems?

Regardless of where it was built bet toyota is losing billions now. Their reputation has taken huge hit - sort of amazing that such a large company would allow this type of issue to go so long that they virtually stop selling cars!

[Porcharu]

And some people want real drive by wire with no 'unreliable' mechanical linkages. Easy to implement variable ratio steering bla bla bla. No thank you sir. The though of my 750ft/lbs torque DBW diesel truck going wide open is not fun, that thing totally overwhelms the big brakes at full throttle (fun for making lots of tire smoke!)
I like my nice simple 914 and 1980 everything mechanical Volvo and will be driving them for a long time.
Steve

[Jaymann]

Well:I HAVE 2007 CAMRY so I am thinking of wearing my motorcycle helmet.If you get pulled over speeding,just blame it on the car.I know this is serious,but there is not much ,I CAN DO except wait for the recall stuff.I just bought this used,the end of october.My last car was a camry, I put 212,000 miles on before I SOLD IT. Put your foot on the brake,and the car in neutral.Pull over turn off ignition.Jaymann

[Katmanken]

Think Toyotas are bad....

Fly Airbus. Then you can enjoy a several thousand foot drop while the computers think about reseting themselves..... (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/blink.gif)