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Toyota RAV4 Throttle Lag

24

Comments

  • bob777bob777 Posts: 19
    Hmmm
    This is interesting. Thanks for the info. Should I be looking at something specifically? I don't find much on the Rav4.
  • lirlir Posts: 81
    For those of you that have had the throttle lag problem and have taken it in to the dealer to be serviced, was there a solution? a fix? Has the condition gone away? I took my RAV4 to the dealer today for that very reason, but the mechanic was not optimistic. He said that is a HUGE problem with the RAV's and there's been no recall. I am very upset because this is a big safety issue, I almost had 2 accidents yesterday, and had I known this, I would have never in my life bought this car. I'm hoping there is a fix and that maybe I hear a bit of optimism from you guys.
  • rickcorickco Posts: 3
    I, too, have the "lag" problem with my RAV4. Unfortunately, I have received the exact same response from the service tech at the dealership(others have reported this problem, but as of this date, there is no "fix"). I reported the problem on my second trip to the dealership and I felt it was "blown" off by the attendant even though it was written down as a problem. On my voice mail message from the tech saying my Rav4 was ready to be picked up, the tech said they could not duplicate the problem and no action was taken(the car was driven around three miles to try to simulate the problem).

    If anyone knows of a solution for this "lag", I would be happy to hear from you.
  • lirlir Posts: 81
    I got the same response that you got. The tech drove with me, and noticed it, but unfortunately there is no fix. He said the computer is getting used to my driving. That was funny! Anyhow, same answers I've read before (drive by wire). He said happens to a lot of cars. Oh well.
  • jimd4jimd4 Posts: 877
    I think lots of service guys BS on this topic at dealers.
    Two Audis, 8 years, almost 100K miles. Both "fly-by-wire".
    No lag under any conditions. The only way you know it is a computer throttle is that when you put cruise to 70 you can tell the pedal is not at 70 Mph position. It is at idle it seems.
  • lirlir Posts: 81
    I agree the dealers like to BS on this topic - I talked to 4, all gave me the same song and dance. I will see how the car behaves in the next week. I really love my RAV4, but if the situation gets worse, then I will reconsider selling it. Like I said before, it is the safety issue that most concerns me. So far today, it did not act up.
  • user777user777 Posts: 3,341
    try adjusting your foot position on the accelerator, specially if you tend to be more of a toe tip driver.

    i.e. move your heel closer to the pedal so more of your foot is in contact with the accelerator.

    some people in other forums report this has helped reduce the lag they experience.

    it's been a theory of mine and a few others that there is excessive slop or play (mechanical compliance) in the pedal assembly, and possibly it needs to be replaced...

    however, no one has had that done that i know of, and it is conjecture. there are many theories about there being a transmission problem, a programming problem, shift solenoid problem, throttle body problem. it's really hard for anyone to know.

    that said, one owner of another toyota model (can't remember if camry or avalon) modified their pedal to make it stiffer in some manner and reported an immediate improvement, but later, his problem returned. that coupled with the foot placement reports does seem to point to the accelerator assembly as a potential root cause.

    anyway, give the foot placement a try and see if it helps. good luck.
  • wwestwwest Posts: 10,706
    First,given the number of Toyota and Lexus vehicles (2002 and on...) appearing to be subject to this delay/hesitation symptom, mostly FWD or front biased AWD, and DBW, very few are actually incurring it.

    To me, that would most likely point to something unique those few drivers are doing, quite possibly, probably, exacerbated by a so-far hidden (deadlock/deadly-embrace) flaw within the engine/transaxle's ECU firmware.

    The issue of foot placement, to me, provided something of a clue. Back in the fifties we knew, learned, that automatics would upshift more quickly with a slight momentary lift of the accelerator pedal.

    It has also become pretty clear to me that almost all modern day vehicles have automatic transmission control firmware designed to extend FE via adoption of certain techniques put forward in an engineering white paper published by Sierra Research late in the last century.

    Foremost among those was something referred to as ASL, Aggressive Shift Logic. The basic idea was to upshift the transmission at every possibility and thereby reduce the engine RPM to extend FE. There were at least two others, one of them being the use of the torque lockup clutch in lower gears to reduce "slush pump" losses provided the engine wasn't under heavy load.

    The shop/technical/repair manual for my 2001 AWD RX300 clearly indicates the above two features are in use.

    My 2001 911/996 Porsche C4 has DBW, but a manual gearbox. Since it's predominantly RWD, and with a definite rear weight bias, I can use engine braking quite safely if I wish, even on a somewhat slippery surface.

    So, how do you "treat" your accelerator pedal when you simply want to coast down to a lower speed, maybe even come to a full stop, VERSUS how do you treat it when you anticipate a need, during coastdown, to quickly accelerate?

    In my case in the 911 I might downshift and then leave the clutch engaged (until almost stopped) but lift the throttle in either case. Were I driving a FWD and the roadbed a tad slippery I would no doubt disengage the clutch should I have one available.

    On the other hand were I anticipating a need to "soon" accelerate I would disengage the clutch while leaving the transmission in the most appropriate gear for the upcoming acceleration.

    The firmware designers at Toyota?lexus have a rather difficult task. The firmware must be designed to upshift the transmission at every opportunity, a 9.8% improvement in FE is not to be sneezed at. And not being able to forecast and with no method to detect a somewhat slippery roadbed except after the fact, their design bias will not allow them to allow a downshift except on explicit and "certain" commands from the driver.

    As User777 has said, higher foot placement on the accelerator pedal does seem to have had a positive effect. Posters trying this have said they have encountered fewer instances of delay/hesitation via using this method.

    Higher foot placement would mean needing more foot pressure for a give distance and shorter travel distance for a given throttle opening. It would also mean, very likely, QUICKER release of the accelerator pedal, and coupled with the shorter distance involved this might just be the rear clue we're after.

    I have no doubt, absolutely NONE, that the firmware is written to detect the difference in the release RATE, and/or partially released position of the accelerator pedal in order to determine the correct action to take with regards transaxle activity, shift up, down or remain in the current gear ratio.

    A quick, definitive, FULL release of the accelerator pedal would undoubtedly indicate a wish to coast down to a lower speed. Whereas a partial release, or a "slow" release, possibly even toward a full release, might be interpreted as a desire to enter cruise mode, in which case an upshift would result.

    So, the priorities become...

    1. Upshift for "cruising" whenever possible, feasible, for best FE.

    2. Upshift on the slightest indication of "coast down" to best prevent loss of control from engine compression braking's interference with ABS on the front wheels.

    3. Downshift ONLY with definite, definitive, action by the driver, action such that there can be no question but that the driver wishes to accelerate.

    See, the "deck" is stacked against you, quite firmly against you.

    But try the following.

    Do not "feather" the accelerator pedal in these instances, be a highly definitive "on/off" type of person/driver.
  • user777user777 Posts: 3,341
    But try the following.

    Do not "feather" the accelerator pedal in these instances, be a highly definitive "on/off" type of person/driver.


    you should only have to lift the foot off the accelerator pedal when applying the brake. if that doesn't work in these cars, it's game over.
  • wwestwwest Posts: 10,706
    As you drive along the highway sometime, look at how many, or really how few, drivers are cruising along NOT removing their left foot from the brake pedal.

    And I'm not saying you must remove your foot entirely from the accelerator pedal.....or maybe... I am....

    With a DBW accelerator pedal now with a light duty return spring, can we really tell that leaving our foot "resting" on the accelerator pedal isn't having the same type of effect as those that are clearly, unconsciously, applying pressure to the brake pedal?

    More and more I am beginning to think a heavier accelerator pedal return spring, or a "torque motor" might be the solution.
  • wwestwwest Posts: 10,706
    for:

    FR Doc 05-1433

    interesting reading.
  • fordmfordm Posts: 3
    NHTSA Consumer Complaint sent 22AUG06: There is a problem in acceleration delay/throttle lag in the 2006 Toyota RAV4. After taking delivery JAN06 and while driving 11K miles, I have experienced erratic acceleration problems. From complete stops or rolling starts, when turning corners in either direction, on uphill grades, or attempted passing, there is a significant delay in delivering forward speed regardless of what pressure is applied to the accelerator. After the delay, forward speed is delivered unexpectedly, causing the car to lurch forward suddenly. The forward speed lags continuously up hills, depending on the grade. Under these conditions, everyday driving is hazardous. I have experienced several close calls.

    The Toyota dealer dismissed initial complaints, stating that this was 'normal', and I put up with this for too long before insisting the vehicle be checked out. The dealer said no error codes were generated and no TSBs had been issued, and that they would have to duplicate the problem in order to fix it - as though we were the only people with this complaint. After some persistence, they gave the impression that they're well aware of a problem, but seem to be stonewalling while laying the blame on Toyota to issue a fix.

    This is a very dangerous fault. My online research has now proven very educational and has revealed that there are numerous complaints of this same problem on various forum websites. For Toyota dealers to pretend this is an isolated, insignificant problem is, at the very least, deceptive and may prove to be criminal, since this acceleration problem could easily lead to an accident.

    Note: I feel User777's treatise on the intricacies of the footfeed, while appreciated and interesting, has no bearing on this problem. I've driven most everything since the mid-60s with no problems adjusting to the vagaries of each vehicle, but this car is just impossible.
  • wwestwwest Posts: 10,706
    You might try some left foot braking.....

    I suspect that were the brakes applied when you enter a coastdown period (release the accelerator pedal partially or even fully) the transaxle would not upshift as it does otherwise.

    I know this is asking you to adapt your driving style to what we all consider a serious flaw in these vehicles but you might want to try it temporarily just as an experiment.
  • Stever@EdmundsStever@Edmunds YooperlandPosts: 38,950
    Sorry for the interruption Willard, but there's a thread you (or anyone else) may be able to weigh in on about engine overrun and "zero" fuel usage while coasting. It's got my curiosity up.

    steve_, "Auto101: How To and How it Works!" #246, 24 Aug 2006 11:09 am
  • user777user777 Posts: 3,341
    not a treatise, just an observation from following several forums where toyota and lexus model owners are experiencing hesitation: that some owners experienced better operability by adjusting their foot placement.

    if the accelerator pedal assembly with its position sensors or the throttle body valve with its position sensors and actuator had an issue with compliance, or calibration or "zeroing", what you are experiencing is exactly the sort of thing you should experience under the circumstances.

    unfortunately, it is speculation.

    noone has proved or disproved it, but one person got close my physically modifying his accelerator pedal. hmmm. i have proposed a means to acquire some objective information to prove my assertion, but noone has followed up on it unfortunately.

    i sense your frustration (apologies if i've increased it in any way) and further that you are making a meta-point or two:

    your foot placement and how you apply pressure is not helping the condition at all - it's simply not a matter of the car "training" you up on how to drive it ala you getting used to how it works. fundamentally, it doesn't work right.

    if so i agree 100%. everything is not normal with your car. the dealership has seemingly come to admitting as much.

    ask your dealership's head mechanic if it could be a problem with compliance or slop or a non-linearity in the throttle body position sensor or actuator, or sticktion, or same in the accelerator pedal mechanicals or position sensors.

    good luck.
  • wwestwwest Posts: 10,706
    Please note that there is no conflict, absolutely NONE, between my current "fix" theory and the foot placement and/or accelerator pedal slack or stiction issue.

    If the pressure point "used" by your foot to actuate the accelerator pedal is higher up on the pedal then the amount of pressure you need to use to move the pedal will be higher, maybe MUCH higher. Additionally the distance your foot must travel for a given throttle opening would be lessened.

    Both of those parameters would contribute to the probability of the engine/transaxle ECU "seeing" a QUICK and FAST lift of the accelerator pedal compared to your normal accelerator pedal application/release at a lower position of the pedal.

    A QUICK and FAST release of the accelerator pedal would be more likely to convey an intent to coast down to a lower speed rather than an intent to enter cruise, perhaps now simply maintain the current speed.

    I have suggested that those experiencing the delay/hesitation may wish to try simulating my "circuit" by using left foot braking. When you foresee that you might, will, need to accelerate just after a coast down period then try this:

    As you release the accelerator pedal (QUICKLY and FULLY!), use your left foot to apply the brake just lightly enough to turn on the brake lights. That should, undoubtedly, prevent the engine/transaxle from interpolating your actions as a desire to enter cruise mode and thereby prevent an upshift. With any luck at all it will leave you in the current gear ratio, at least, and may even result in a downshift.
  • fordmfordm Posts: 3
    My apologies re treatise, user777, I meant to refer to wwest's posting. I appreciate the responses, but I refuse to do left-foot braking - it's the principal of the thing. Will explore the accelerator sensor angle, though.

    But regardless of if I have to stand on my head in order to accommodate this car's glitches and to drive it safely, the fact remains that there is a problem with this car and unsuspecting RAV4 owners should not have to be the ones to deal with it.

    I plan to follow up by letter with Toyota hq and dealer, and hope to get some response from NHTSA to my ODI.

    Stay in touch - thanks.
  • This is an interesting observation. The lag/lack of downshift happened to my wife recently. She does keep her foot a bit low on the throttle. I assume you mean center to low on the peddle. Still it has happened to me a couple of times and my foot is placed more center to high on the peddle, so I don't think foot placement is the cause.

    I just got back from a different Toyota dealer I bought the car from. They said it was due to what they called the fly by wire programing in the on board computer. Seems they've had this before. They gave me the 800 Toyota number to call, because there is nothing they can do about it. They also said other vehicles also do it.

    I hate to say it, but I'm becoming uneasy with this vehicle.
  • wwestwwest Posts: 10,706
    On another forum an owner seems to have discovered that not only does left foot braking often prevent the transaxle from upshifting, the prevention of upshifting leaves the transaxle "set", prepared, to accept a downshift command if/when the next accelerator pedal depression is aggressive.
  • I have driven my wife's 2006 V6 Limited about 6000 km so far under various driving conditions, both city and highway and have not yet experienced any throttle lag. Vehicle has responded well to passing gear on 2 lane highways, entering intersections from a Stop sign, etc. Feels just like the old fashioned cable system. Whatever the problem is, it is not systemic across the whole vehicle line.
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