MinisterofDOOM wrote:I can see it being beneficial in a couple of places, but not anywhere near beneficial enough that it's worth the added complexity.
An electronic throttle is not really that different than a TPS sensor. It adds a motor at the throttle to control it but where the simplicity actually occurs is with the implementation of cruise control and traction control devices. Cruise control devices tend to be complicated with an external motor and an extra throttle cable. Not to mention I've personally seen cases where it made the throttle stick (it didn't cause any accidents, but the symptom was a high idle as the throttle cable from the cruise control motor was a bit out of position after an accident). There are some known recalls that involve throttle sticking caused by cruise control systems. As for traction control, it eliminates the need to use fuel or ignition cuts to cut power. Its likely safer for the motor and can be tuned to be less abrupt than typical fuel and ignition cuts. One thing Nissan has done as well is to dial back the throttle between shifts with their automatics to help smooth out the shift. And of course there is the rev matching Nissan has been using on the 370Z.
As for safety, it does present a potential problem, but this is something that Toyota seemed to half-a** it on with some of its implementation. Car and Driver had a great article on this in the newest issue. Part of it brings up a potential that the e-throttle was not entirely to blame as they did tests with three cars, including a Roush Stage 3 Mustang, a G37 and a Camry V-6. All were able to stop with throttle fully applied from 70 mph. It took longer, but they stopped. The Camry was able to stop from 100 mph in only about 75 feet more. They did try the Carmy from 120 mph in which case, it still got down to about 10 mph before the brakes faded conmpletely. The Roush was the only one that had a problem at that speed as it ended up taking nearly 900 feet to stop. The G37 (along with all Infiniti/Nissans) cut throttle if the brakes are applied so its distances were very lightly affected. This was a point C/D made though is that this type of programming should be applied to all cars with E-throttles.
All the cars were able to shift into nuetral with the throttle pegged, so this type of way to deal with the problem is still usable.
One thing they also tested was the ability to shut off the motor in a panic. Most specifically with push button start vehicles. Holding the button down shuts off the motor. The G37 shut off in 2.5 seconds while the Camry shut off in 3.3. But perhaps more importantly, the G37's start/stop button was programmed so that 3 quick presses of the button will shut off the motor. The Camry did nothing. C/D claims that most people would probably try and press the button several times quickly in a panic situation. I tend to agree for the most part.
As for the hardware itself, I can't speak to Toyota's implementation as I know nothing about it, but Nissan uses redundant systems to make sure that there isn't an improper signal being generated by the sensor at the pedal. If the signals do not match, then an engine code lights up. I'm not sure what it does with the throttle, but I'd speculate it goes into a limp mode.
