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Unintended Acceleration - Find the Cause



  • imidazol97imidazol97 Member Posts: 27,146
    >but when they are investigated, most are found to be driver error.

    I'd like to see your documentation for that opinion. Got a link?

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • itsjustmattitsjustmatt Member Posts: 3
    Very well said mkriley! I was going to make a post stating almost exactly what you have. I personally know 2 people who have had accidents because they pushed the wrong pedal. You can go on to youtube and watch videos of people running into stores because they hit the wrong pedal. When you hit the gas while trying to hit the brake and the car accelerates instead of stopping, even the most intelligent mind spends precious seconds trying to sort out those 2 conflicting inputs before realizing what he is doing. If there are cars close in front of you an accident is very likely. I absolutely agree, these problems will not go away until we remove the human from every aspect of driving a car.
  • mkriley1mkriley1 Member Posts: 3
    My own daughter drove through my garage door because she thought she hit the brake but hit the gas instead. Cost me $1500. She was driving a Mazda. Did I sue Mazda? Did I file a complaint with the NHTSA? Either action could have kept me from writing the $1500 check. But my daughter owned up to her error, and I just gave her a hug and paid the bill.
  • elfgrrrlelfgrrrl Member Posts: 1
    I think hackers may have hacked into the electronic systems of these vehicles experiencing difficulties via onstar. Remember than Onstar can help, for example, to start your engine during difficulties, etc.

    So it is logical that the source of the difficulties is that people have somehow hacked Onstar and maliciously unbalanced certain variables with their hacking.
  • a_l_hubcapsa_l_hubcaps Member Posts: 518
    The discussion about sensors is interesting stuff, but I'm seeing surprisingly little in this thread (or in any of the discussions/news stories about this problem) about software. There's a lot of assumption that as long as the pedal assembly is sending the proper voltages to the computer, there cannot be a problem. Given how rare and intermittent the problems are, it seems a lot more likely to me that it's a software bug that's only triggered under specific circumstances. It may have no relationship at all to the voltage signals coming from the pedal -- it could be something like a buffer overrun triggered by a completely unrelated section of code, that's clobbering data that the computer is using to decide how to move the throttle.

    If there is a "real" problem here at all (that is, separate from the floor mat and sticky mechanism problems already fixed), I don't think it will be found unless we can analyze the software.

    -Andrew L
  • a_l_hubcapsa_l_hubcaps Member Posts: 518
    Just thought of another question. Does anyone know about the interface between the pedal assembly and the ECM? Is it like the "old days" where the sensor just outputs an analog voltage signal through a wire, and the ECM interprets the signal internally? Or is the pedal assembly a "smart" device, that is itself converting the sensor outputs to digital data and using CAN-BUS or something to send its data to the ECM? If the latter, that opens up possibilities for data from the pedal being somehow interrupted or corrupted in transit to the ECM.

    -Andrew L
  • wwestwwest Member Posts: 10,706
    "..media and US government have turned this problem into an opportunity to discredit..."

    No, the media may have opened the door, and the US government may have held it open, but the way I see it it was PURELY Toyota/etc that made the decision to walk through that door totally ill-prepared.
  • steverstever Guest Posts: 52,454
    cold solder joints

    Is there any correlation between using more solder and "whisker" shorts?
  • wwestwwest Member Posts: 10,706
    I believe "whisker" shorts are most often the result of the printed circuit board etching process. Small copper tiny whisker paths that should have been etched away but were not. Sometimes these "paths" are not quite complete until the solder flow process bridges them.
  • plektoplekto Member Posts: 3,738
    edited March 2010
    This link you provide addresses only mechanical failure of these pedals, but I was under the impression that there were electronic problems identified.
    The electronics/software act as a final fail-safe should there be a mechanical or electrical problem. As was pointed out previously, unless you *properly* design the feedback system, and/or the software is badly written, you leave yourself open to these sorts of failures.

    Toyota cut corners somewhere by the looks of it and the worst did happen.

    Can this technology work? Probably, if properly implemented with proper fail-safe designs. Is it better than a simple throttle cable? I don't see how, quite honestly. Note - GM as an example again, spent a small fortune on potentiometer failures under warranty, so it's not a very good method either. (though decently safe if it fails) Most modern systems like this in other applications tend to use purely solid-state optical sensors for exactly this reason. They're a bit more expensive, but are amazingly robust and failures are easy to detect. No signal = shut off, signal doesn't vary for x amount of time = off, etc.

    If you have, say, a variable between 0 and 1023(keep it simple of course), no human can possibly maintain a value of 565 for 30 seconds straight. It'll vary a tiny bit. If it doesn't, they're probably asleep or there's a problem with the optical sensor. This isn't much harder than the programming that controls and monitors the mouse on your PC.

    Removing the mechanical part is an obvious step if they want this to work correctly. But I'd still rather have a throttle cable.
  • ronjamronjam Member Posts: 1
    the most likely cause of the gas system sending to much unwanted gas to the motor is caused by outside electrical interference--this messes up the sensor system controlling the flow of gas.
    Better shield on the electric system will most likely clear up the problem.
  • wwestwwest Member Posts: 10,706
    edited March 2010
    "...Toyota cut corners somewhere..."

    That's not necessarily the case.

    Have you ever seen an errata sheet for any of the more common microprocessor integrated circuits...?? Oftentimes these processors have been long in use and still customers find/discover anomalies in their operation in some form or another, out of sequence instruction execution being just one of the many.

    I seem to remember that one of the early Intel 80486 microprocessors had 4 pages of errata descriptions within a year of it becoming available. The current multi-core, QUAD, Pentium has at least one instruction execution sequence "fault" that I am aware of.

    But the more likely suspect IMMHO is that some outside influence is resulting in the engine control computer, microprocessor, executing an instruction, or group of instructions, out of sequence.

    As I have said before, that could result from any one, or even a multiple of the various RFI/EMI sources within the vehicle itself, the A/C clutch being one of the primary suspects. Then there is the possibility of an "upset" due to short term sagging or surging voltages on the 12 volt system. Maybe even a ground bounce problem due to the use of the vehicle's metal chassis for a ground return path/circuit.
  • plektoplekto Member Posts: 3,738
    Toyota themselves recalled the parts and has blamed one supplier(so far), so there is evidence for corners being cut or the design not being followed properly for the fail-safe implementation. Testing that I've read about suggests that these units did in fact NOT operate properly when they failed and as a result never told the computer that they were broken/weren't detectable as such by the computer.

    Now, it could have been pure mistake, but there's currently rumors of Toyota also recalling the Denso units as well. This might be due to legal and public perception issues, though, but I suspect it's also because the design isn't good enough for this application. It's probably less expensive at this point to design an optical design(this would be my choice) and retrofit every car than deal with the lost sales and legal battles.

    note - even new security gates that you get for your driveway now use optical sensors because the mechanical sensors fail fairly often. My father was getting his repaired the other day and the guy told him that they were all optical now and far more reliable. And, to be honest, I've not had an optical mouse on a computer go bad on me in a very long time.
  • jiml8jiml8 Member Posts: 9
    edited March 2010
    To explain a situation where one computer can lock the throttle down while another computer won't apply the brakes, and the thing can't be shifted into neutral or shut off using the "shutdown" button (formerly the ignition key), we either have to invoke multiple failures of a specific type or we have to find a common linkage among these various systems that can account for the problem.

    Modern cars use high-energy alternators and many of the voltage regulators in those alternators are switching types.

    This leads to the possibility of a regulator filter failure that will allow high frequency voltage spikes onto the car's power lines. There is on-board regulation for the computers that is supposed to clean up power issues, but these regulators are generally small and of very limited capability.

    Voltage spikes arriving on the computers' power lines, given the right conditions, can cause some of the gates inside the device to switch states, leaving the computer in an illegal state. It is entirely possible that such a problem would affect all the computers in the car, and the resulting symptoms would be intermittent, seldom repeatable, and very hard to diagnose.

    Such a problem could not be solved with a software fix.

    I personally have encountered this exact problem on a 91 Toyota Celica GT-S. The car has antilocks, cruise, and electronic transmission. It displayed intermittent and sometimes strong random acceleration (but only when the cruise was engaged - and the cruise always disengaged immediately when the brakes were applied), intermittent and random inappropriate activation of the antilock brakes when brakes were applied, and random inappropriate up and downshifts with the transmission. Resetting the entire system by cycling all power with the ignition key would stop all symptoms, sometimes only for seconds and sometimes for hours.

    For awhile, I hunted for bad grounds. Finally I had an inspiration and hung an oscilloscope on the 12 volt bus, and spotted voltage spikes of several volts both positive and negative, with pulse widths typically in the tens of microseconds on the power line. Sorry, I can't be specific; I wasn't collecting data; I was fixing my car.

    I replaced the alternator and all symptoms vanished. I do wish now that I had kept the alternator, but I did this last spring before all of this became an issue.

    If there is a reasonably common failure mode for the alternator or the rectifier or the regulator that can allow these high frequency spikes onto the power bus, then everything is explained. Alternatively, if there is a situation involving some moderate to high power electronic transmission system (data links, radar, cell tower, radio station, mobile communications devices) that is not properly filtered by the power system in the car, then still everything is explained.

    Such spikes will cause intermittent illegal states in the computers. Those intermittent illegal states may or may not be cleared by the computer. Those illegal states can cause acceleration, and can cause braking problems, and can cause transmission problems. They also are difficult to reproduce, and may vanish for significant periods of time either due to temperature, environment, or some other factor such as vibration.

    For the unlucky few individuals, the combination of computer malfunctions will lead to a car that accelerates uncontrollably and can't be stopped.

    I have done power system analysis for military fighter aircraft and helicopters. Those power systems are always dirty, and military avionics has to be able to tolerate it. This is not a trivial problem, but it is one that can be solved. If we are going to have "drive by wire" cars, then we have to solve it for cars.

    The quickest "fix" for such a problem is to provide all new cars with a "reset" button which, when pressed, mechanically removes all power from all critical electronics in the car. Thus, when a malfunction occurs, you hit the reset button, and when you release it all computers reinitialize. This capability needs to be present anyway; there has to be a positive way to get control of the car back when everything else fails.

    The proper fix is hardware in each computer that can tolerate ANY power system faults, that will automatically reset the computer when the computer malfunctions. This can be done, but it costs more.

    The best fix is multiply redundant computers, multiply redundant data paths, and redundant power. However, that is not cheap.

    By the way. I hold a Master of Science in Physics and have a lot of experience with these types of problems. And I consult.
  • cbrechlincbrechlin Member Posts: 11
    I believe I've read stories of sudden and inexplicable acceleration that apparently had nothing to do with the mechanical position of the pedal. It is such a scenario that, as wwest has described, that a true double-parallel fail-safe system is missing. This would not 'back up' the type of mechanical failure described at your link, where the pedal either remains at the floor or returns slowly, it would merely read where the pedal was and respond accordingly.

    One remedy for that kind of mechanical failure would be the inclusion of a pressure switch or optical sensor located under the pedal rubber, where no acceleration is possible when there's no foot on it. Since it is noted that Toyota pays about $15/ea for these pedal assemblies, it will near double the price to install the sensor and related wiring. If they really wanted to make these safe, they would also have double-parallel circuited full-throttle and no-throttle switches that work in conjunction with the location sensor, where all the switches are mutually exclusive and thereby protects even against mechanical failure. This sure seems like a lot of complexity to replace a cable doesn't it?

    If it turns out that all or most failures are the result of bushings/springs failing to return then it should be obvious that mechanical redundancy is overdue. We use mechanical redundancy in brakes and throttle body valve control already, accelerator pedal? Gosh, who'd a thunk it?
  • wwestwwest Member Posts: 10,706
    edited March 2010
    What was the bandwith of the oscilloscope you used...?

    A narrow bandwidth and those "spikes" could have been 30, 50, even 300 volt spikes in the nanosecond range and your scope wouldn't have displayed them.

    Most of the electronics equipment aboard Boeing airplanes must continue to operate with 300 volt "noise" spikes on the 28 volt buss.
  • charlie97charlie97 Member Posts: 1
    I haven't seen any mention of it possibly being the Cruise Control.
    I had a Ford Taurus a few years ago that had a similar problem.
    It involved a RESUME function that didn't know when to quit accelerating and the brake pedal cancel function sometimes didn't cancel.
  • cbrechlincbrechlin Member Posts: 11
    FYI, the "encoders" I mentioned are optical... it's an enclosed optical disk with a thousand hash-marks that spin on whatever mechanical ratio feeding the computer extremely accurate and reliable location info, these were one of those items that never seemed to fail. They would probably double or triple the $15 cost too. However, hall sensors are cheap and just as unlikely to fail. The other advantage to hall sensors over optical sensors, like a mouse optic, is debris; it is far easier to minimally protect a hall sensor than an optical sensor which would need to be air tight... it gets really dirty under there especially in the north with salt and snow half the year.
  • puffin1puffin1 Member Posts: 276
    i must concur with your conclusions as a former pilot. Puffin VFMA 323 CVN Nemitz
  • plektoplekto Member Posts: 3,738
    edited March 2010
    True, but the position sensor itself could easily be in a sealed area of the mechanism. Optical would be the best solution now, IMO, since once this gets out, the public won't want any of the old technology and for legal reasons the manufacturers won't touch it,either. So that will leave something they invent brand-new, optical, or maybe go back to a throttle cable.

    But the real reason they are so keen on all of this is because they want control of our vehicles at some point in the future. Now, this isn't tinfoil hat-time. You can see that OnStar commercial yourself. They can remote start, stop, and eventually control your car.

    Imagine the following scenario:
    You get off of the highway and the computers in the car sync up with the local cellphone services or nav system. You aren't on the highway so the car limits itself to 40mph. If you enter a residential area, it drops to 30mph. If you speed or try to get around it somehow, it sends a signal and you get a ticket for speeding. If you are in an accident, it tells your insurance company how fast you were going and for how long(already does this on quite a few cars).

    There's really no other practical reason for an expensive and impractical drive-by-wire system in a car other than the fact that someone wants to be able to gain control if they want to. That OnStar ad really is an eye-opener if you step back and look at what else it implies.
  • cbrechlincbrechlin Member Posts: 11
    Totally agree with the Reset Button, I can't believe they're not in there now either. I've had to install my own on several devices over the years when relatively primitive computers would accidentally store wrong info, shorting out a c-moss battery to clear it.

    I do however, think a true double-parallel fail-safe with comparison circuit can and does protect against even computer failure. The way our system worked was that the comparison circuit would self-check 27 different sensor positions (a gas pedal would not be this complex obviously), both positives and negatives for each, every 5 milliseconds. If for any reason any one of those conditions, including the computer itself, was out of tolerance, no operation was possible. In other words, it's a circuit designed NOT to operate unless all 64 sensor conditions and the self-check were perfect (according to the engineered tolerances that is). A severe enough voltage spike could trip the system and that would only need to be programmed into this specific pedal problem as one of the factors. If Toyota has or designed a separated system just for the throttle, a reset to protect against spikes should be very simple, perhaps even automatic.
  • shamannorashamannora Member Posts: 2
    edited March 2010
    This problem with Toyota cars reminds me of an issue Volvo had over 25 years ago. My mother crashed into a bank with her Volvo because it suddenly accelerated and she could do nothing to stop it. For years Volvo denied there was any problem with their fuel injection, but years later finally admitted it and made a correction in future models. I think Toyota has a fuel injection problem, not a mat or pedal problem. The fuel injection somehow is shortcircuiting and overpowering the braking system by giving it more gas and more power.
  • cbrechlincbrechlin Member Posts: 11
    The message is not lost on me about OnStar, that was the first thing I thought when they first came out, besides, I happen to be a 'truther' and don't trust any corporate marketed product or service without looking thoroughly behind the curtains. But further, there are many more reasons I refuse to update beyond my early '80's Audi's: ABS is one of them... no way am I ever going to trust any computer for navigation of any kind on the road in the real world (qualifier noted below). Over-Computerization is another very important one... at what point in history do we get when landfills/yards are full of mechanically sound suv's and other modern miracles that are there ONLY because no one makes the specific computer to run them anymore? Aside from that picture, how can people have any intimacy with their possessions when they have no clue what is actually happening in the processes they assume they are controlling? I personally think a big part of the material illness in this country comes from people accepting that they don't need to understand what the specialists are up to, cars in this case, but medicine and government, add in all the others. I insist on being intimate with anything I depend on, knowing how everything I have came to being and operates and for what purpose.

    As a qualifier, note, I can see a future potential of "I-Robot" style automated all-electronic traffic systems that can be manually overridden in order to achieve speeds that human reactions are too variable for. I drove the autobahn for a couple of years and it has always been my presumption that most travel SHOULD be maximized for speed with safety as a precondition. It's fun and efficient to drive at 150mph when cars, roads and other drivers are properly equipped. I think what Toyota is doing is building in as much of the 'drive by wire' technology as possible before the whole industry turns into a Nissan Leaf type machine... highly simplified mechanics with superior response. A car like the Leaf in fact is likely to be my next cash car purchase (never ever taken a loan on a car) because the maintenance will drop to nearly zero and cost of operation as well when properly built. I can even see how cars will outlive people, perhaps by 2030.

    That's all a lot of talk, isn't it? :confuse:
  • investigator41investigator41 Member Posts: 1
    I am not a tech so to speak but I am a bit knowledgeable of how to use EMP, RF and other types of frequency emitters to disrupt computer operations. Has anyone stopped to look at the types of cell phones, jack systems, blue tooth units, and so forth that have been present or in use in the vehicles involved in these sudden acclerations incidents, or what environment they were in where frequency transmitters may have been in use at the time of the incident?

    It occurred to me that the problem may be a bigger picture than just the vehicle itself. Possibly a shielding issue versus a defect?
  • navvetnavvet Member Posts: 1
    How close to cell phone repeater towers were the vehicles that suddenly took off? I ask this as I installed a citizens band radio in a new '87 ford Ranger, the first time I keyed the mike the truck took off then died. I had to reset the fuel pump, which was controlled by the ECM on the truck. This was in 1987! Considering the advanced electronics in cars today, I'd assume that even the use of a cell phone would be enough to disrupt the programming in the ECM. Cell towers can expell a large amount of energy in short bursts (think sunspot) that can throw off the programming. Think about it.
  • sasseelynsasseelyn Member Posts: 1
    Problem lays in either the cruise control system or trottle body.
  • jnhksjnhks Member Posts: 1
    One cause for this is an inconsistent fuel supply. In many NASA space vehicles---such as the space shuttle---there are small retro rockets that allow for navigation of the craft. In addition, prior to firing these rockets the valves that feed the combustion chambers for these rockets must be 'recycled' prior to using them (e.g. watch Fred Haise in the command module in the movie Apollo 13 and you'll see this procedure in action) . This process consists of purging the valve and resetting the valve with a fresh mixture so that the rocket will instantaneously fire when activated. If there is too much air, too much fuel, or none of either, the system won't respond properly. Has anyone considered air bubbles or a general lack of continuity in the fuel system supply (the physical lines; not the electronics) that causes surges? Small air bubbles in fuel lines can be expanded by running fuel lines too close to heat sources. That's my million dollar two-cents worth.
  • jakepickjakepick Member Posts: 1
    edited March 2010
  • lvisionlvision Member Posts: 6
    The sudden acceleration happened to less than 1000 Toyota cars. Why bother to question the same design is on millions of cars??? All of them didn't have the problem.
  • jlaskajlaska Member Posts: 1
    Whisker shorts is on the right path, but to be more correct it is called "tin whiskers". The situation is caused by lead-free solder and it occurs over time. This makes perfect sense, since I recently learned that in all the cases of unexpected acceleration it occurred in vehicles that had over 100,000 miles on them. Many years ago lead was added to tin solder to improve the qualities of the solder. In recent years, the Japanese who own about 86% of the disposable electronics market, discovered that if they removed the lead from the solder the tin whishers effect would cause cell phones, walkmans, PDAs, etc. to fail more frequently and thus consumers would have to purchase them more frequently. To gain support for lead-free solder the Japanses told the environmentalists that lead in the electronics in the land-fills was leaching into their wells. Naturally, the environmentalists jumped on the band wagon even though the truth is that only a very miniute percentage of lead was leaching into the water supply from the land filss. NASA experienced the problem years ago & mandated no lead-free solder be used in any of their electronics. In a sense, Toyota is correct when they say nothing is wrong with their electronics because nothing is wrong with it until tin whiskers causes it to short out then there is a problem. Prior to that occurring they can run all the fault tests they want and it won't show up. One sure way to verify this situation is to have Toyota ask their electronics vendors if they used lead-free solder in the maufacture of their electronics components.
  • a_l_hubcapsa_l_hubcaps Member Posts: 518
    "I do however, think a true double-parallel fail-safe with comparison circuit can and does protect against even computer failure. The way our system worked was that the comparison circuit would self-check 27 different sensor positions (a gas pedal would not be this complex obviously), both positives and negatives for each, every 5 milliseconds."

    The weak point in this kind of setup is, you're assuming that the problem exists somewhere between the pedal mechanism, and the code in the ECM that monitors the state of the pedal. However, the position of the throttle plate is not a direct function of the position of the pedal. There are other software pieces like cruise control, possibly stability control, that are in the mix when the computer determines throttle position. It's possible that the detection of the pedal position is working perfectly fine, but some other factor, such as a bug in the cruise control or stability control code, is causing the computer to command wide-open throttle. Adding more redundancy to the pedal sensors won't fix a problem like that.

    -Andrew L
  • lvisionlvision Member Posts: 6
    edited March 2010
    Find the car in which the owner experienced sudden acceleration.
    Buy it.
    Drive around an empty field while changing all the possible stimulus that effect the throttle.
  • steverstever Guest Posts: 52,454
    edited March 2010
    haven't seen any mention of it possibly being the Cruise Control.

    While the US, Canada and Japan blamed operator error for the Audi 500 SUA cases, I've read that the Swedish government placed the blame on the cruise control.

    Jlaska, thanks for the tin whisker post. :)

    I have a one-stop solution to SUA and distracted driving btw - remove the accelerator pedal and go to hand controls. Take both hands off the wheel and the car slows down.

    steve_, "Toyota Halts Sales of Popular Models - Accelerator Stuck Problem Recall" #2046, 3 Mar 2010 7:44 pm
  • larryscottlarryscott Member Posts: 2
    There is only one system on all vehicles produced that can cause the vehicles to accelerate by themselves. It is the cruise control system, which is linked to the ECM and all sensors including the throttle position sensor. Toyota knows this and anyone who works on cars should know this too.
  • chuckles951chuckles951 Member Posts: 1
    I am an electronics engineer. Finding what is causing intermittent mis-operation of a firmware driven circuit can be extremely difficult. Especially since the offending hangup may never occur again in the code.

    In fact it may be almost impossible to track down something that is this rare. Consider that the microcontroller cannot be totally crashing because if it did lock up, the ignition would cease.

    Looking at the wiring diagram for a 4 cylinder 2008 Camry as an example, the same engine controller that controls the throttle body also runs the injectors and the coils. It also runs the transmission and it is possible whatever "brain blockage" that is opening the throttle when it is not supposed to could conceivable prevent a person from shifting into neutral.

    What we need is is an external hardware override to be wired into the cars so that the engine will always return to neutral when the brake pedal is pressed. I could design one of these myself needing about $10 in parts and needing perhaps 6 connections in the car.

    This reminds me when I designed a microcontroller controlled amplifier once and I had the temperature sensor being read by the microcontroller. And the microcontroller would shut down the amplifier if it got too hot.

    This amplifier was rejected by CSA and UL. Because the safety override is not allowed to be controlled by a microcontroller. In case the software/firmware fails. I had to put an external hardwired loop into the design that did not depend on a software controlled device to operate.

    I can see the reasoning for this and I added a 25 cent logic gate to the unit to provide a hardware fail safe.

    I see no reason why retrofit kits cannot be made for all "drive by wire" cars to do this.

    As well, if we want to get the combined engineering brain power of the engineering community to attack this problem and solve it, Toyota should post their full schematic diagrams of the engine controller on the internet as well as the full source code for the microcontroller inside.

    Yes, they will be giving away some inside secrets but the rapid solution thousands of engineers would develop would more than make up for any "technology leakage"

    And we need to open up some of these controllers to see if there is indeed a tin whiskering problem or not.
  • phantomirqphantomirq Member Posts: 1
    Some time ago I was working with the DSP from a reputable vendor. After several years of a successful deployment and after some firmware modification of this DSP based device I started to experience under specific conditions a spurious system failures that can not be explained. Investigating the source of this I have found that nothing was really wrong in my programs and completely benign change of the code line order resulted in the problem elimination. It happened I have discovered and was able to reproduce the so called "Phantom Interrupt". An event randomly forcing the DSP in the reset and the recovery mode. Fortunately my system was not managing the car's power delivery system so nobody ended up around the tree or in the ditch. There is a hint that Toyota's problem is related to the Accelerator release or Break application. Those are events that could cause either firmware code contention or something similar to the "Phantom Interrupt" at the MPU level..
  • cloudseedercloudseeder Member Posts: 5
    I think you're onto something but it's more than just fuel injection surging.
    There must be a corresponding voltage surge slamming the sparkplugs.

    Extra Voltage + Extra Fuel = Imitation Dieseling Condition.

    Solution #1: Toyota and all automobile companies could place a voltage limiter cap on the plugs or they could be incorporated into new plug wires. No extra voltage = no extra dieseling no matter how much fuel is pouring into the cylinders.

    Solution #2: Wouldn't hurt to slap a Jake Brake engine limiter on the engines.
  • wwestwwest Member Posts: 10,706
    Dieseling in a gasoline engine is the result of too little fuel in the mixture, a lean mixture, not a fuel rich one.
  • prabhatkrprabhatkr Member Posts: 1
    edited March 2010
    My dynamical analysis of standard system shows that it is case of saddle node bifurcation. probably, due to multiple electronic controls assuming linear behavior creates a race situation. World is nonlinear!
    And quite easily minor changes could tame the system.
  • mccreedymccreedy Member Posts: 2
    Copy of an email that I sent Toyota a few weeks ago:

    Dear Sirs 2/24/2010

    You’ve probably already checked this out, but is there any possibility that the “Uncontrolled Acceleration” problem may not be mechanical or electrical?

    I could see that under certain conditions of temperature, humidity, atmospheric pressure, throttle plate position and engine demand, ice could form on the throttle plate, locking it in position. If locked in the optimum position to cause even more ice buildup, it would be nearly impossible to jar the throttle plate loose by tapping on the accelerator pedal.

    After the event was over, all evidence of this “lockup” would remove itself (ice) causing diagnosis to be nearly impossible.

    I’m not trying to presume to know more than your engineers, but sometimes people are too close to the problem to look at it objectively.

    Regards and good luck in solving the problem.
  • cloudseedercloudseeder Member Posts: 5
    edited March 2010
    Dieseling in a gasoline engine is the result of too high a compression ratio. A sudden glut of fuel {filling the cylinder more} ~preceded by an extra voltage pump~ would cause such a compression increase from excess fuel displacement, the extra fuel taking up space => reducing the area inside the cylinder.

    Bear in mind I defined imitation dieseling condition, so you can claim anything about regular, normal dieseling all you want. Apples and oranges. A gasoline engine that "diesels" {runaway} is usually an overheated engine, so what I'm defining is a very fast temperature escalation inside the cylinder ~caused by excessive voltage~ ergo Imitation Dieseling. You'll see it when you think outside the box => a gasoline engine that diesels is usually incorrectly timed. The voltage jump would be causing such a condition...
    bouncing the engine into instantaneous Super Throttle.
  • hackattack5hackattack5 Member Posts: 315
    "ice could form on the throttle plate"
    What about the car in California in the summer or others in the summer? Are you saying that the A/C unit is causing Ice on the throttle plate?
  • hackattack5hackattack5 Member Posts: 315
    Not 1 car imported from Japan is affected by the recall. How does Toyota get their cars all the way from Japan to the USA?
  • rushellrushell Member Posts: 1
    Some have mentioned rf here. I can remember when I had a cb radio with a 600 watt linear amplifier in my truck. It would light a florescent light bulb from a distance. I could wreak havoc to a rc aircraft hundreds of yards away. Has anyone considered all the truckers out there with high powered cb amplifiers who are constantly talking (transmitting) on them?
  • mccreedymccreedy Member Posts: 2
    No. As the pressure drops and the velocity increases on a gas,(in this case, the air going around the throttle plate) the temperature drops also. Punch a hole in a CO2 bottle to see what I mean. The moisture condenses out of the air going to the engine and deposits itself as ice on or near the throttle plate. This phenomenen can and does ocurr at temperatures well above freezing. I happens very very often on the throttle plate of my tractor.
  • cloudseedercloudseeder Member Posts: 5
    As to what caused the voltage to sudden-spike like that ~thereby causing the temporary dynamic creation of an imitation dieseling condition~ one previous poster made a good case for lead-free solder being used in the electronics module. He called it "tin whiskers". My answer is not in conflict with his. He defined a possible and very plausible cause while I defined the mechanics of what was happening afterward, which I think was what Toyota wanted, not just spit out answers but also wanting understanding.

    So I reckon we'ill have to divide the $1,000,000.00 purse. Rats.
    Toyota is getting multiple answers for their $1 million cost.
  • omewillemomewillem Member Posts: 4
    You do know that a lot of Toyota's with the same problems are actually build right here in the USA?
  • omewillemomewillem Member Posts: 4
    How can one explain sticky pedals if not pushing the thing down first to get it stick? If one just drives around and the pedal sticks, it sticks where your foot had it last, probably at 55 mph... If it decides to suddenly accelerate, as an engineer I have a hard time believing it is due to a sticky pedal. I've been saying from day one it is most likely in the firmware, not hardware. Drive-by-wire does not sound that bad now, hey? Or it is the US government trying to make GM look good......
  • mikal44mikal44 Member Posts: 1
    What we need is access to one of the cars with the problem even if it has never reproduced the problem again. But more importantly we need all the exact answers to these questions how many cars were really affected, a company report on what problems they really have already ruled out and the types of test they ran to rule these out. We also need full access to all schematics. I also feel i could be in the lead free soldier but why then don't the same cars reproduce the condition repeatedly once the soldier has broken down. There may be several other variables that are causing this problem
  • flaviusflavius Member Posts: 3
    Check out my post, no 20 where I blame the cruise control, several people have had some nasty experiences with cruise controls on Renault Logan. :)
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