Comment pots & encoders fail with unpredicable results (Score 1) 690
If these cars are drive-by-wire then I'd be suspecting that the potentiometers and/or positional encoders that are used to read the throttle position are failing (or starting to fail) as potentiometers and encoders do.
Can anybody in the know verify what sort of technology is used to actually read the throttle position in cars these-days (not for the TPS sensor so much - but for the drive-by-wire setup)? I'm hoping it's not potentiometers because the resistive layer can wear through on those with age causing unreliable behaviour. Even if they're using rotary or optical encoders, they can have dodgy reliability problems when they age (grease/lubricant starts to age) etc. Who hasn't had a stereo where the volume control has started getting flaky after a few years?
I'm sure that the manufacturers have thought of simple things like this, which makes me think that there's either people are making this stuff up, or there's something screwy with the car's control software or electronics. If it's a software error then, as another poster has already pointed out, no amount of pontificating is going to solve the problem without giving us access to the source code.
Of course, it could be something more sinister. Perhaps the CAN bus command to signal 100% throttle to the ECU happens to be easy to trigger with a particular type of noise? Again, nobody is going to be able to figure that sort of stuff out without some serious insider knowledge..
I hope they do figure this out though as my car happens to be a reasonably recent model and is drive-by-wire. Although I'd like to think I'd have the presence of mind to kill the engine or throw it in neutral if there were any problems, until you're put in that situation it's really hard to know how you'd react.