Posted on 03/07/2010 11:12:34 AM PST by Oklahoma
How to Handle Sudden Unintended Acceleration: Video
In this video, PM senior automotive editor Mike Allen accelerates his car to 55 and then stops it—while the throttle is still open.
DO • Brake. Brake once, don't pump or ride the brakes. This will only heat up the brake pads, potentially overheating them and making them fail. It will take more force than you're used to to make the vehicle stop. Use both feet if you need to. • Shift. Move the gearshift into neutral. If the throttle is truly stuck, the engine will redline and make a lot of noise, but it won't be damaged. The injection computer will keep it from over-revving. Leaving it running will keep the power brakes an power steering working normally. Obviously, if your car has a manual transmission, simply stepping on the clutch pedal will slow the car. • Steer. Steer your car to a safe place off the road and away from traffic.
DON'T • Pump the brakes. • Shift into park. (Which won't engage at speed anyway.) • Drag the brakes. • Shut off the engine. (Well, shut off the engine as a last resort, but it may affect the brakes and steering, which will become heavier, although they'll remain operational.)
It is several steps away from steer by wire. There’s still a mechanical shaft connecting the wheel to the rack, for example. And GM’s explanation of the problem does not gibe with what people who owned the cars have found - it’s the circuits acting weird and shutting down the pump, not the other way around.
Actually, I was just at the Dallas Auto Show. Mercedes has withdrawn Sensotronic from the US market as it did not work well and has no plans to bring brake by wire back. None of the other makers plan on BBW any time soon, either.
The reason these people were not able to go into neutral was because they were pushing right and up on the lever. This goes into the manual gear selection quadrant on the unit. You can’t get into neutral from there, you have to push straight forwards or left and forward to go into neutral. The only Toyotas that are shift-by-wire are the hybrids, and few if any have had any issues with SUA to date that I can find.
As for the TPS - your understanding of what they did and how was incorrect. Also, GM’s sticking them out on the throttle body resulted in a lot of environmental kills - the short life of a GM TPS is legendary. Toyota’s current TPS are inside the cabin where they are protected from wind, water, snow, winter, etc., and the old GM ones were actually exposed to that. If the TPS reported full throttle was being commanded, the engine wouldn’t flood and die - there would be a brief burp and then the car would just run rich. Fuelling was more commanded by the manifold air pressure sensor and the oxygen sensor. The TPS was used for acceleration enrichment keying. The engine would not flood and die.
GMs were also notorious for continuing to run once you’d removed the key from the car. Not such a great disconnect there.
Looks like they have moved in this direction even if they were not totally there.
Gear shifter
2010 Toyota Prius Generation Three
No mechanical linkage. The gear selector operates a shift-by-wire mechanism to manipulate the CVT (continuously variable transmission).
Yes, that’s what I said - the hybrids are the only ones with shift by wire.
That’s because Toyota is planning an upgrade pack to convert them to a serial hybrid and eliminate the transmission entirely.
Ok you make some good points. I do have to say that I have owned many GMS since the 80’s. Never even had a TPS fail. Although I have heard of them failing.
The point was however that if the butterfly is closed then it is totally impossible for the the engine to high rev...No matter what else happens. I feel confident that if the system tried to do so then the engine would flood and die. It is no different than full revving your riding mower, and then activating the choke. To much fuel...Too little air... Spark plug gets wet and shorts out. Black smoke. Cough and die.
Yes I saw that you posted that after I replied. You obviously know more than I do about Toyota.
Hopefully you do agree that The ignition switch should still provide an instant manual disconnect of power to the ignition/fuel circuit upon request.
Unfortunately, this was not so. A broken PCV hose (common) or failed IAC (also common) could cause the engine to rev way up.
Remember, it was difficult to flood even a TBI engine, because the computer would read the situation with the oxygen sensor and adjust. So you are incorrect on that.
No, because ignition switches fail on a regular basis (go to your local parts store and check out the selection of replacement ignition mechanisms they stock sometime).
I think there should be a kill switch, as there is on motorcycles, of the punch/slap button type, mounted in a conspicuous and easily accessed place in the interior.
Many cars already have that feature built into the braking system. No button is necessary, the brake pedal serves that function. Toyota didn't think this feature was needed. They were wrong.
Well I have vehicles with both types of fuel injection. Maybe this summer I will dismount the TPS and move it to full throttle with the engine running. It would interesting to see what happens. I was not aware that the computer had the means to supply extensive air to the engine via other means. I have seen the PVC failure you are talking about, and the increased revs. But nowhere near full throttle. Of course you are now talking about multiple failures existing at the same time. I have never heard of any other car running away like this except once. Back in the old days I knew of a case where the choke kick off linkage came disconnected and jammed the Throttle at the carb.
So what do you think that at the same time that your engine decides to full rev when you are driving down the highway...That your ignition switch is going to fail at the same time? I never had ignition switch failures. But from what I hear some of the newer cars (Including GM) are having a big problem there. So sad that cars are made with such garbage now. I actually read about the GM ignition switches failing with as little as 3000 miles on the car(The key won’t even come out). These are the same cars that are under recall for the electric power steering.
TBI vehicles could have the same problem as carbs and literally freeze in the open position. Likewise their linkages can get screwed up.
The computer can supply quite a bit of air to the engine via an IAC that’s stuck wide open. Multiple failures are common to see in a shop because GM owners often put off repairs until they pile up for a bit.
I had a Ford F150 that you could turn off and take the key out of, and it would keep running. This is a common problem for domestic vehicles, especially for people that keep heavy keyrings. It has been a problem for more than 30 years, too.
And yes, if Murphy is hunting for your butt, you’re going to have other things go wrong.
Remember also, shutting off the ignition will also lock the steering wheel on a lot of cars, or if you turn the key too far under stress. Then you have an unguided missile.
Well then maybe having both methods present to kill the engine is a good idea. Your kill switch needs to be a mechanical disconnect of power though. Not simply a digital input to the computer telling it to shut down. Thanks. I think that I am going to try and find older cars for as long as possible when I need another one. I really think they are making unsafe and at least unreliable junk now. My brother has a Montana. The power window switches melted inside in less than 3 years. I took the switches apart. There is no way they could not fail. What junk. Any heat on the contacts melts the plastic that holds the contacts. Of course a power window motor is going draw enough current to generate heat at the contacts. No recall though. Remember when such switches used Bakelite or some similar heat resistant material? Now they use romper room plastic.
The problem isn’t newer vehicles per se, it’s cheap execution.
Nissans don’t seem to have such problems, to pick one example. Many cars don’t run the power through the switches, they use relays instead. A lot of the domestics have been stupendously slow to adopt innovations like that.
Yup My Buick in the 80’s used relays. I have a diagram for the Montana. It does not. Disappointed me really. One thing I could always say about GM. They were way ahead on electrical systems. They were most always the first in innovation in that regard. Built in voltage regulators(so reliable), Watertight connectors, Side post batteries(connections almost never fail), Ect... Everyone one tried to copy them(And took years doing it). Now they may be going stupid.
GM has rarely been the first in innovation since about 1970.
Well we will never agree on that...LOL Remember I am only talking electrical systems here. I forgot to add High Energy Ignition to the list.
Yes, and that’s about where it ended.
They were slow to adopt EFI, pouring millions into the R-Type system which never worked, and then were slow to adopt multiport fuel injection.
They were slow to offer overdrive transmissions, being 10 years later than almost everyone else in the world to even offer one.
They were slow to adopt composite headlights, bitterly lobbying against them.
The list goes on and on.
I missed the conversation last night but I agree with you on most of the main points.
After all is said and done most of the problems are caused by floor mats and panic. When you consider the total numbers the problem is small and the reaction is overblown. For the remaining problems Toyota’s record is probably better than the other manufacturers’.
For Revel, it’s been shown over and over that the current models can be stopped using the brakes even when the throttle is set wide-open and you CAN shift the automatics into neutral. Except allowing for panic there is no excuse for the accidents in a majority of the cases. All of these new cases showing up now are most likely “trial lawyer” inspired.
I disagree that the floor mats are actually the problem - several cases have come to light where the car took off and the floormats were in the trunk or not even in the vehicle at all.
However, unless you’re a complete idiot, you should still be able to flip the vehicle into neutral and safely brake the vehicle to a stop. Unless, that is, you panic, freak out, and lock up - which unfortunately is what a lot of people do.
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