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Lexus RX 350 Unintended Acceleration

wwestwwest Posts: 10,706
edited March 2014 in Lexus
I continue to see reports of this problem, of late mostly due to carpet or floor mat creep. The floor mat creeps forward over time and ends up lodged over the bottom of the gas pedal but under the brake pedal. Apply the brakes moderately, the gas pedal gets depressed....

I even had this happen to me on two occasions. About 8-10 years ago in a new Mazda Miata test drive the dealer's thick cardboard protective mat got trapped between the gas pedal and the brake pedal. The second time was last year in a Mazda minivan on vacation on Maui. The OEM carpet wasn't secured.

So, is it time to add yet a second unintended acceleration FAILSAFE along with the need to firmly apply the brake in order to shift out of park..??

Now that many new cars have DBW, E-throttle, why not disable the throttle altogether, drive it closed, any time the brake pedal is depressed..?? Or even with DBW just use the EFI system to starve the engine of fuel in the same way my RX "dethrottles" the engine upon TC activation.

The left foot brakers would not like it initially but they would adjust and then get the benefits of improved FE and longer brake component life.


  • la4meadla4mead Posts: 347
    I see where you're going with this, but I must say I disagree completely. There is absolutely too much "big brother" built into it, for too little benefit. It's good that you want to bring this up for discussion, but it should be in the proper forum. I think your title is very misleading; it has nothing to do with unintended acceleration in this model, but more about protecting from operator error in a way many would find unacceptably obtrusive.

    If I fail to secure my mats (Lexus already provides a very secure clip for the drivers mat), that's my fault and I don't see a need for this to be programmed into the car. There's already too much meddling on part of car manufacturers protecting themselves from liability when they should be concentrating on building safer, more efficient and durable cars that are fun to drive and easy to live with using inherently safe designs. I'm all for the proven benefits of a well-behaved stability control and ABS system, but sometimes it's taken a bit overboard, and preventing simultaneous throttle and brake control would be one of those times.

    I don't see a significant safety benefit for the benefit you are proposing. I don't want to release any more control of my throttle to an electronic lawyer than I have to for optimal functioning.
  • wwestwwest Posts: 10,706
    First, I think I did my very best to not make this marque or model related, even contacting one of the hosts to try and discover how. When I filled out the "new discussion form" I even deselected those automatic entries. Obviously to no avail.

    But, also obviously, "this model" could be subject to the problem as well.

    "For too little benefit.."

    Tell that to someone who has actually driven into a busy intersection, or worse, due to a carpet mat, luckily I'm not one of those. And it isn't necessarily the OEM floor mat/carpet that results in the problem, it may very well be, moreso, the aftermarket "weather" mat.

    "they should be concentrating on building safer.."

    And if "this" isn't about safety then how would you classify it...??

    And tell me, just when might you be noticing that the gas pedal doesn't respond when the brakes are applied...??

    Totally, TOTALLY, non-obtrusive...FAILSAFE....!!

    "I'm all for the proven benefits of a well-behaved stability control and ABS system,...."




    See link.
  • steverstever Posts: 52,683
    I did my very best to not make this marque or model related

    I sort of wondered if you meant to park this in the Lexus RX area. We could move it to Automotive News or Maintenance & Repair. That way you'd attract the Audi crowd too. :)

    Ditto your ABS discussion.
  • la4meadla4mead Posts: 347
    I respectfully disagree with the logic of your argument. Since you know aftermarket mats are a problem for you, I suggest you remove them or correct that problem (apparently unsafe design), rather than proposing to add more electronic lawyers which cannot be disabled, imposed across the board. That's too much Big Brother watching over everyone.

    I'd need to see hard data on how much this could help provide a safer environment for everyone it affects. Your argument does not convince me that deleting simultaneous brake and accelerator control would be totally unobtrusive.

    Perhaps the title should be "slipping aftermarket mat safety" and it would help more accurately describe the problem of the discussion. I'm more concerned about the soda can under the brake. But I don't drink soda, and not proposing to outlaw beverage containers in cars.
  • wwestwwest Posts: 10,706
    First, if you browse around the net you will find quite a few unintended acceleration complaints that seemingly, drivers attest, have NOTHING to do with slipping carpets or mat. Reason unknown.

    Locking out the gas feed with brake application might put an end to those also.

    I'm pretty sure the incident in teh Mazda minivan involved the OEM mats, I don't remember what the resolution was other than discovering the problem and moving the mats back and notifying the owner.

    "I need to see hard data...."

    Why, do you have doubts that the problem exists...??

    Or have doubts that it is potentially life threatening..??

    Perhaps you could tell us under what/which circumstances you think/feel it might be obtrusive..??

    Most vehicles that have the brake/park lock also have a manual bypass method, maybe that would please you in this case..??
  • dkshdwsdkshdws Posts: 1
    I just filed a complaint with the NHTSA concerning unintended acceleration!

    I bought my 2005 Tacoma about 2 months ago. I have experienced this problem three times now. The last time being tonight after picking up my daughter at work. The truck was accelerating and I was literally standing on the brake and the engine was racing and would not stop. I through it into Neutral and it sounded like it was going to explode! I have no rugs in my vehicle, it did not come with any, and I was going to get the all weather mats, but have not bought them yet. The cruise control was not engaged. I do consider myself to be a fairly experienced driver, I use to race a 70 Chevelle in the 1/4 mile (This was many years ago.), if I did not have such experience I am sure I would have ran the car up a tree or something. I am scared, I have beat cancer twice and Ill be damned if I am going to let a faulty Tacoma take me out!

    The issue is real! does anyone know a way to fix the issue? Is there a mod that locks out the gas feed with brake application, if not can this be done?
    I can make my car duplicate this issue yet nothing is getting done! What steps should I take next anyone?

    Thank you!
  • jayvisjayvis Posts: 76
    Get a different car.
  • tidestertidester Posts: 10,059
    The money has already been spent and "getting a different car" simply passes the problem on to the next unsuspecting person, i.e. there is no resolution.

    tidester, host
    SUVs and Smart Shopper
  • la4meadla4mead Posts: 347
    I agree... I'd be determined to keep trying to get to the bottom of it, too.

    It doesn't have an aftermarket cruise, alarm, obstruction (carpet, plastic panel, loose bolt, cable, clamp, misplaced heater duct, tire iron, water bottle) or anything like that? I know it sounds extremely silly to look for the obvious, but it could be anything. If there's anything else like a throttle cable or cruise servo, or even the engine cover or throttle itself... It could be anything from the pedal to the EFI.

    I'd be determined to find it right away, rather than in fear of it being unsafe. Maybe a search on the Tacoma forum might reveal if other owners of that model had a problem, and their solution. What if it is inherint in an electronic drive-by-wire? That surely would come up by now, unless you're the first person it's happened to.

    I hope you find your culprit. I'm pretty sure you will now that you have the incentive of a possible runaway truck. But it's most likely to be something obvious. But I feel for you.

    My mom had two Mavericks! :lemon: They both had differing "runaway" car problems. The '70 250CID I6 and a '72 "GRABBER" 302 V8. A combination of a weak auto shift linkage and hand brake that couldn't hold the car on level ground no matter how hard you pulled, and a very determined idle. My mom didn't learn with the first one, and got another that was worse because it had the torque to pin you in after it fell in "Drive" or "Reverse" as you were getting in or out of an idling car. One time, I heard my mom screaming, and there were 4 big guys from her apartment building picking up the rear of the car. It was off the ground running in gear. When they dropped it back on the ground, it ran into the apartment building. They were busy little cars. Ford's fix came in the mail, unsolicited. It was an ugly sticker you're supposed to stick on the dash. It said something like "Do not leave any car idling in Park".

    Then there's my dad's '70 Hornet SST. I was a 15 year old with a learner's permit when the Hornet's throttle cable broke. The pedal fell under my foot, and I pried my foot under it. But it was loose and so was the engine. The throttle opens all the way when the cable breaks on many old models. The car lept forward, chirped in "first" and right through a red light in a busy section of the San Fernando Valley. It screamed at redline 1-2, then into 3rd. I was going 75 before I got the ignition to cut. I couldn't believe they could make cars that way, even as a youngster. And it didn't have "power" brakes, either. Those were the days. :surprise: Not trying to belittle the concern for safety. I wouldn't want to put up with it, either. I'm curious to hear about it.
  • wwestwwest Posts: 10,706
    The easiest and simplest "fix" would be to use the 12 volts from the brake light circuit to energize a relay.

    Then the relay contacts could be used to...

    "Drive" the DBW throttle servomotor to idle.
  • steverstever Posts: 52,683
    What do you think about today's recall news?

    Toyota Recalls 2.3 Million Vehicles to Address Sticking Accelerator Pedal (Edmunds Daily)

    This discussion is a bit out of place since it really didn't start out being about the RX 3XX, and that model isn't on the recall list.

    Yet anyway....
  • wwestwwest Posts: 10,706
    What do I think..??

    Not a surprise.

    The time has long since passed for the designers to have begun using firmware to DRIVE the throttle opening servomotor to the idle position with the brake applied.

    Or use a torque motor on the gas pedal itself instead of a spring. The torque motor could then be used to provide the driver with vibratory feedback if/when wheelspin/slip is detected.

    Many of the new EPS, Electronic Power Stearing, systems now use ("directed" by VSC) differential power stearing "assist" torque to prompt the driver to not turn the stearing wheel in the wrong direction.
  • tuna5tuna5 Posts: 1
    I bought a Lexus RX 350 (brand new from Kendall Lexus in Eugene,Oregon) in 10/22/09. I noticed when I got it home that when shifting between gears the engine frequently revs up (1000-2000 rpms then catches the next gear). I talked to the dealer when I had some service work done in November 2009. I was told it's a common problem, a computer chip is faulty and it won't hurt anything. It's still doing it and I'd like to know what to do. Is there a phone number to talk to someone higher up in Lexus?

    Thank you,
    Chuck Brook
  • wwestwwest Posts: 10,706
    These new 6(9) speed transaxles will often use the torque converter lockup clutch in the top 2 or 3 gear ratios, not just OD. When you change gears the lockup clutch will get disengaged until the ECU has time to "judge" the engine load factor in the new gear ratio. So, momentarily you will be making use of the torque converter which results in a higher engine RPM than if/when the lockup clutch is subsequently engaged.

    But even so, 2000 RPM does seem extreme, 1000-1500, maybe.

    You might experiment with turning the OD switch off and on in different gear ratios and engine loadings to get an idea of the engine RPM changes with and without the lockup clutch engaged.
  • jsdtxjsdtx Posts: 11
    Friend of mine took is 07 ES 350 in for an oil change and 4 hours later they gave his car back after reshaping the pedal, removing foam from under the carpet, reprograming his computer, and filling up his gas tank for free. Lexus is dishonest in not recalling the ES and the SUV based on the Highlander. They have the same acceleration problems. I will not buy a Lexus or Toyota product again. NEVER
  • wwestwwest Posts: 10,706
    A recall on a Lexus...

    Horror of HORRORS...!!
This discussion has been closed.