Toyota RAV4 Throttle Lag

steverstever Guest Posts: 52,454
This discussion is to figure out what to do if your RAV4 suffers from throttle lag.


  • mikenew2mikenew2 Member Posts: 4
    I too have had my RAV4 for about 3 months, 2wd 4cyl sport. I have noticed the downshifting issue more and more. I had no complaints about acceleration when i first got the SUV, but it has become a noticible issue, so much so that passengers comment on the jerk when the transmission downshifts. In traffic, when I need to pass or change lanes, the tansmission clunk and throttle lag is almost dangerous. I have started feeling that I cannot live with a car that performs this way for long.

    On the other hand, I have not had any problem with braking.

    Another criticism is the build of the interior, which seems cheap and loose - lots of the plastic seams don't seem well fitted, the window switch plate came out of the door once while pulling up on the switch to close the window. My previous Toyotas seemed more solid.
  • bob777bob777 Member Posts: 19
    Throttle lag is a good way to put it. I think it's dangerous and I thought I was going to get nailed both times it happened to me.

    The break issue seems to happen under emergency breaking situations. They work ok at first but then begin to fade. Hard breaking from say, at least 45 MPH.
  • mikenew2mikenew2 Member Posts: 4
    I have not had any particularly hard braking incidents, knock on wood, so I can't speak to it. But I will pay attention if it happens. Not looking forward to what my dealership will say about the transmission and throttle issue... :lemon: ???
  • bob777bob777 Member Posts: 19
    My dealer told me I needed to learn to drive a Toyota and learn how to avoid these situations. I'm taking it to another dealer, but I doubt they will admit anything until there is an accident and they have to by court order.

    The break issue happened early on. They have gotten better with additional miles and I would say they are satisfactory now. May have been an issue with new pads.
  • fsmmcsifsmmcsi Member Posts: 792
    Is this the same problem as people are having with the Avalons? I notice that both models have a 5-speed automatic transmission, while the Camry has a 6-speed unit.

    I have decided to rent one for an extended test drive, and have discovered that some Toyota dealers rent new models. Toyota's vehicle rental web site even promotes rentals for such extended test drives.
  • bob777bob777 Member Posts: 19
    I would not be surprised, but I don't know. Renting one is a great idea. I wish I would have thought of that.

    My brother in law has an 06 Avalon and he has no issues with it.
  • mterrellmterrell Member Posts: 21
    I bought the 2006 base 2wd and I have noticed a lag in exceleration and brake fade. Seems that its got better now that it has about 1600 miles on it. So maybe it a break in thing with this suv . The lag could be a problem though I have notice that a little more when the ac is on and the car is cold . You dont want to trust it for a quick take off. If it continues it will be take to be serviced.
  • mterrellmterrell Member Posts: 21
    Well love the car! hate the the hesitation when you need power to pass or get out of the way. seems "there could be not always" a 3 or 4 second delay in down shifting from overdrive (D). Its is either the TPS or a trans relay. Has any one else notice this problem?
  • lirlir Member Posts: 81
    I have the 4 cylinder and haven't experienced that, but my friend has the V6 and is having that same problem. I also read people having that same problem in another forum. Looks like it can happen to 4 or 6 cylinder RAV4's.
  • petlpetl Member Posts: 610
    I'll be blunt. I don't believe there is a 4 second delay.
  • bob777bob777 Member Posts: 19
    When it first happened to me I was pulling out of a lane of traffic heading aross two lanes for an exit. The delay seemed longer than a couple of seconds to me and 4 is not out of the question. In fact it never did downshift that time, even with my entire weight/strength pressing the accelerator to the floor.
  • jimd4jimd4 Member Posts: 877
    I would think that is a real hazard and you should have a serious talk with your dealer if not with the National Highway Safety guys
  • mterrellmterrell Member Posts: 21
    Thats what mine did although when I let up on the gas it down shifted. It has done it to me twice .Once was when it should have down shifted and the other from a dead stop. I talked to dealer service and they have not received complaints. Because mine did this from a start at a red light makes me think something is going on with the tps .Just dont seem very responsive. I have almost 3000 miles on it and now its not just a break in deal? is it?
  • mterrellmterrell Member Posts: 21
    I have to say that going up to 89 octane has made a difference. Cost a little more but with the variable timing it make a noticeable difference.
  • bob777bob777 Member Posts: 19
    The dealer does not want to deal with the situation. They want to blame it on how I drive and not the car. The National Highway Safety folks is an interesting thought. Have you done this before? If so, what happened?
  • jimd4jimd4 Member Posts: 877
    have never done the NHSI stuff. But if enough people write it will get attention.

    But really, call the Toyota main number or write a letter describing your concerns. Let someone drive the car with you there and see if their style makes it drive different.
    Work on your dealer. Take it too another dealer. On the RAV4W site there are similar complaints but low numbers of them.
  • bob777bob777 Member Posts: 19
    I hear you and I am taking it to another dealer. But, Toyota is not reacting in a responsible manner on this.

    It does not happen all the time, but instead only under certain situations. I can and do avoid the lack of down shifting by doing it manually now, but I did not think of that when it happened the first couple of times. It was clearly unsafe those times.

    Toyota needs to fix this not me. They have enough input to know there's a problem. Also, I have written them. No action at all.
  • haha11hahahaha11haha Member Posts: 4
    I have 4x2 4 cyl with 11500 miles on it.

    I am getting somewhere around 27-28 now highway miles, before it was around 24-25, with full load 20 highway.

    But now I the engine got very noisy.

    Haave most of the problems described on Edmunds forum.

    Windows rattle, i was told that it is a design flaw. Was fixed,noise came up again, they are going to replace the whole power window system.

    Electronics is glitchy. Had wird stuff with LCDs, nonreadable symbols. VSC and ABS were lit up for several weeks, cruise control didn't work until they cleared computer memory second time.
    These are hard to verify problems... I have to run to a dealer every time I see it, otherwise they wont believe me. They joked on my RAV4 saying I got Ford Explorer. And everytime I come to the dealer all management comes out and looks at the problems saying WOW this is first time we see it. liek it helps. Toyota Motor Corp does not want to do anything yet. Lemon law doesn't fit yet... So I have no clue what to do with it.
  • bob777bob777 Member Posts: 19
    Man, I wish I could tell you I've been successful with Toyota dealers. They seem to want to put the problem onto owners. The issues I have are with the lack of downshifting, breaks the faded even during the first hard breaking and gas mileage that was a bit low.

    I hate to say this, but persistency seems to be the key.

    They've, Toyota, seen these issues, but they have been able to put the proof onto owners instead of taking ownership of problems and solving them.

    I've had quite a few new cars over that last few years and I have not had anywhere near the same experience with them. I'm talking about Ford, Mazda, Nissan and even Chevy. I'm trying to figure out why people think so highly of Toyota.

    My gas mileage is starting to get better. I have over 8K miles on it now and it now gets over 24 MPG during mostly in town with some highway miles.
  • bob777bob777 Member Posts: 19
    This is interesting. Thanks for the info. Should I be looking at something specifically? I don't find much on the Rav4.
  • lirlir Member 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 Member 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 Member 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 Member 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 Member 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 Member 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 Member 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 Member 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 Member 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 Member Posts: 10,706

    FR Doc 05-1433

    interesting reading.
  • fordmfordm Member 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 Member 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 Guest Posts: 52,454
    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 Member 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 Member 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 Member 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.
  • bob777bob777 Member Posts: 19
    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 Member 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.
  • altaredaltared Member Posts: 12
    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.
  • muckluckmuckluck Member Posts: 2
    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 Member 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 Member 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?
  • andrew17andrew17 Member Posts: 26
    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!
  • raviola4raviola4 Member Posts: 52
    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 Member 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 Member 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 Member 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 Member 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.
  • wwestwwest Member Posts: 10,706

    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...!!

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