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Toyota RAV4 Throttle Lag

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Comments

  • 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.
  • steverstever Viva Las CrucesPosts: 41,618
    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

    Moderator
    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • 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.
  • I have throttle lag that is intermittent. I am responding now as when the problem goes away it is easy to think that it was in my head. But last night the vehicle was acting fine, accelerating fine; this morning lots of throttle lag. Have had the vehicle a month, and have seen other discussions that talked about vehicle 'learing' how I drive, etc., so was trying to see if that might be the problem; but now with 1800 miles, I am ready to complain. I really dont want to take it to the dealer and get the 'could not duplicate problem' response; but I also dont want to be stuck with a lemon as I only have the first 15k miles to get it replaced. I have submitted a complaint to nhtsa, and have noticed several other complaints of the same problem.
  • wwestwwest Posts: 10,706
    The vehicle could be designed to learn each individual driver's style/technique only if we all agreed to be "chipped". Absent knowing what individual is driving at any given time the vehicle must "relearn" your personal style/technique after each engine start driving session.

    Which is the way it works.
  • jimd4jimd4 Posts: 877
    I guess we will be able to tell if the parking lot guy or the kids ripped the truck huh? When I get in in the AM, the wheels will come of the ground when I try to tiptoe down the street with the V6?
  • RAV4 V-6 AWD (2006): I was told by several people that pulling the CPU (computer) for 5-60 seconds (?) will erase the driving profile from active memory and the throttle lag disappears. (You create a new profile by your own driving habits.)

    Could somebody send me a comment? -Thanks for your time and cooperation!
  • I know i've written to Toyota, and have filed a complaint with NHTSA. Toyota says "normal". I've had 4 instances since buying the car in March i deem serious. Scariest was merging in traffic going 50-60 mph from a slow crawl, plenty of room to merge, but literally nothing from Rav when i pushed accelerator pedal, panic, pushed harder, downshifted yada yada. This also was noted as normal. So when the first person dies from trying to merge as i did and gets clobbered in the side by an 18 wheeler, will Toyota also claim "Normal". :mad:
  • user777user777 Posts: 3,341
    toyota recently issued a TSB for improving the shift / operability in the new Camry models. Look in the 2007 Camry Woes forum. perhaps your vehicle is or will be a reflash candidate.

    there's speculation that under certain conditions, the Camry was programmed to be too lean (fuel / air ratio).

    hard to say, we don't have specifics on the TSB.

    maybe you can contact your dealershop or corporate and ask them if the same issues the people with the Camry are experiencing with their transmission / accelerator are being researched by Toyota for the RAV.

    perhaps a little research on your part (maybe with the help of someone else if necessary): determine for the Camry I4 if the transmission and ECU/PCM (Engine Control Unit/Powertrain Control Module) are the same part number as in your RAV. that might give reason to be hopeful that the re-flash might improve operability of your ride.

    good luck.
  • wwestwwest Posts: 10,706
    None of the ECUs will "remember" personal, individual, driving habits/style beyond removing the ignition key, otherwise the "next" individual driving that vehicle might experience some rather "strange" ECU responses.

    If you remove the battery connections for a period of time, say 15 minutes, the ECUs will need to relearn, recalibrate, some of the individual sensor parameters and that might change the vehicle "reactions" until the recalibration has completed.

    But thereafter....

    There is some evidence indicating that following the battery disconnect procedure each and every night helps to alleviate the engine/transaxle downshift delay/hesitation for most of the next day's use.
  • wwestwwest Posts: 10,706
    Impossible to believe...

    Ford has the answer.....!

    From the new 2007 Ford Edge PR..

    "The electronically shift controlled transmission also features a variable displacement pump, which matches the amount of fluid that gets pushed through the transmission to driver demand, making it more efficient."

    At full lift-throttle all of the FWD Toyota/lexus vehicles begin an upshift just as the engine RPM drops to idle. With the engine at idle the upshift will exhaust/use most, or possibly all, of the pressurized ATF.

    Now if you happen to re-apply foot pressure to the accelerator pedal just as the upshift begins the engine/transaxle ECU will "know" to delay the onset of engine until the low engine "idle" RPM can build enough ATF pressure to complete the corresponding downshift.

    The most obvious answer would be to increase the volume of the fixed volume ATF pump so enough pressure/flow could be provided for two sequential QUICK shifts with the engine at idle. But then most of that added volume would be bypassed, disapated as heat, as the engine RPM rises above idle.

    Ford's answer, apparently, is to have a variable displacement ATF pump so it can be switched to high volume when quick/SOLID shifting is required with the engine at idle. Makes me wonder if that allowed them to eliminate the ATF pressure bypass relief spring/valve also.

    That would REALLY increase transaxle efficiency.

    A second option would havre been to have an ATF pressure storage accumulator (like the ABS pumpmotor asembly). But putting one of those in an already "crowded" six-speed transaxle is probably out of the question.

    Anyone know if any of the newer Toyota/Lexus transaxles have either? Absent one or the other the delay/hesitation issue will undoubtedly continue.
  • fordmfordm Posts: 3
    In 2006 RAV4 4-cyl with 15K miles, using mid-grade or high-test gas seems to help the throttle lag situation we've experienced since day one with this vehicle. Problem's still there but not as frequent. Dealer suggested this, so they must have some clue. Any ideas, anybody?

    BTW, the NHTSA site has even more complaints posted but no investigations so far.
    :mad:
  • wwestwwest Posts: 10,706
    Sure...!

    Higher octane allows the engine to operate in a Taller gear ratio at a low(er) RPM without "lugging", knock/ping.

    So with a higher octane when you initially re-apply pressure to the gas pedal shortly after/during the lift-throttle upshift the transaxle may (more often) remain, briefly, in the "taller" gear ratio since the ECU "knows" that will not result in a seriously detrimental level of Knock/Ping. The ECU would therefore allow the DBW system to immediately begin raising engine RPM, generating additional drive torque, as a result of the new, re-applied, gas pedal pressure.

    So now the engine RPM is no longer at idle and should you continue to increase the pressure on the gas pedal such that a downshift is required to keep the engine in a proper, non-lugging, operating range there is now much more likelihood that there will be be enough ATF pump pressure/flow volume to accommodate the upcoming downshift.

    The above might also be an indication that a fairly s..l...o....w re-application of pressure to the gas pedal after a FULL lift-throttle event might often alleviate the downshift delay/hesitation regardless of octane. Whereas a quick/fast/heavy re-application would almost always result in a serious level of knock/ping absent an immediate downshift.

    Counter-intuitive, huh..??

    Go SLOW, to GO QUICKLY...!!

    Okay...??
  • wwestwwest Posts: 10,706
    Regardless of lack of mental capability of the idiot on the US throne at the moment our government is not altogether stupid.

    Bear with me for a moment and just briefly assume that my theory is correct that these 1999 to current MY transaxle problems have arisen out of the need to alleviate the potential for engine compression braking interferring with the anti-lock braking system.

    If that is the case and an investigation were to be opened the obvious conclusion would be, must be, that absent these new transaxle charactoristics all FWD or front torque biased AWD vehicles are inherently unsafe for operating on adverse, slippery, roadbed conditions.

    So were I the head of the NHTSA I wouldn't dare even open an investigation once Toyota informed me of the base purpose, cause, of these symptoms.
  • steverstever Viva Las CrucesPosts: 41,618
    I've already voted and am hoping to avoid further political commentary for a couple of years so please take that stuff elsewhere. :shades:

    So, go slow to go fast - now wrap that in with transmission "learning" and tell me how confused the car is going to get? :shades:

    Moderator
    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • wwestwwest Posts: 10,706
    Personally I don't buy into that individual driver uniqueness learning bit whatsoever!

    Granted, these ECU's do have to "learn" the charactoristics of the individual sensors and in some cases deterministic forcing functions due to unavoidable tolerances. But I do not believe that any significant level of driver unique charactoristics "learning" is involved in the majority of these "driveability" complaints.

    Yes, most of these systems "watch" driver functions and according to the engineering white papers I have read will categorize each driver into one of four "bins" within a few seconds of first putting the vehicle in motion, and then with more time will refine the characterization into one of sixteen "bins".

    But all of the learning regarding individual driver unique charactoristics is ERASED each and every time the engine is (re)started.
  • steverstever Viva Las CrucesPosts: 41,618
    Some cars do offer "sport" and "economy" modes - guess the next marketing push will be "16 bin selections" on the 2009 Smurfmobile.

    Moderator
    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • wwestwwest Posts: 10,706
    Assuming the new shift pattern upshift technique is to help alleviate accidents due to loss of directional control arising for engine braking, why not just have a SNOW mode that can be activated by the driver, by a rain sensor, or if the OAT hovers around or below freezing.

    Upon a full lift-throttle event in SNOW mode the transaxle would remain in the same gear ratio but the engine RPM, via DBW, would not be allowed to fall enough to provide a significant level of engine braking to the driven wheels, front, rear, or ALL.

    Absent being in SNOW mode the shift patetrn could be the same as it was pre-2000.
  • edr5edr5 Posts: 1
    I have experienced the same throttle lag. Even worse, I pulled into a left turn lane, came to a stop briefly, nothing was coming, so I pushed the accelerator, the engine rev-ed - and the car did not accelerate at all! I pushed down a little more expecting it to kick in - and nothing but engine rev! So I took my foot off the gas completely and after about 10 seconds tried again and it went. I took it to the dealer - they said this was "normal." I repeated this back to the service manager and when you say it out loud "I push the accelerator and the car does not move," then it does not sound so "normal." They apparently did read this forum after I told them this was not the first RAV this has happened to. But they could not "recreate" the problem so they did nothing. The guy did admit that they can now re-flash Camry's with throttle lag, but they are not allowed to do that to RAV's.

    Now the stereo is going haywire. Sometimes it does not respond to the on/off button, and sometimes the display will not come on even though the controls work. Is there some kind of electronic problem that would affect both throttle control and the stereo? Seems unlikely but am curious.
  • user777user777 Posts: 3,341
    edr5,
    i'm sorry that your dealership is giving you the run-around.

    i've cited your post as a good application of a obd-ii reader and laptop to capture the very unsafe and non-normal operational behavior of your toyota vehicle - which your dealer is claiming is normal and won't do anything because (supposidly) they cannot re-create, they are not motivated to re-create, or re-creating will put them in a difficult situation.

    look here:
    user777, "2007 Toyota Camry Problems and Repairs" #4055, 29 Sep 2007 2:12 am

    w.r.t. your stereo: here's what may be happening: do you use the on/off control of the radio a lot? if so, it's possible carbon build-up from many uses (everytime you press on, a tiny spark is generated at the switch contacts causing arcing and oxidation) is causing the switch to fail to close the circuit to power up the unit because of accumulation. it's possible specialized electrical cleaner could be used on the switch if the radio was removed, but you'd best have that theory passed by someone.

    the radio display not working... sounds like it might be a loose connection to the radio or in the radio itself. sorry, i don't know more about the stereo in your vehicle.
  • Dealers will replace bad radios under a Toyota TSB that has been out since earlier this year. Had mine done in the spring after it started either going blank or displaying Japanese characters. The problem has not returned.
  • I have had the same problem on a 2004 and brought it to the dealer's attention mutliple times without resolution. Fall 2007, I was told it needed a throttle body flush and had that done for $125 by the local dealer in Chicago (Grossinger). Today I took it in for an oil change and was told it needed another throttle body flush for another $125 and, by the way, did the throttle seem to stick...... When I challenged the service manager to justify needing another $125 throttle flush in just 4 months, he told me he makes recommendations based on what he sees. Watch out for these vultures. You never know what the real truth is.........
  • I have the opposite problem of the folks with throttle lag on my 2007 RAV4. On a number of occasions when braking to a stop in close quarters, the engine revs to 4000 rpm and I am unable to hold the car with full brake pressure. When I shift to neutral to stop the car the engine revs to 6500 rpm. Same problems with dealer, "no computer record of malfunction, unable to duplicate problem, everything meets factory specs." No help from Toyota either. NHTSA site indicates Lexus drive by wire system had similar problems and they did nothing.
    I found the discussion of the computer reacting differently to different driving styles to be interesting as this has only happened once to my wife who is the principal driver of the car and happens frequently to me, five times in the past weekend. Quite dangerous as I nearly scared to death a pedestrian in a crosswalk.
    What do I have to get Toyota to replace the sensors in the system, assuming that will fix this?
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