Edmunds.com | Inside Line | Auto Observer Your Account | Help | Directory
You are here:
![[F]](http://a332.g.akamai.net/f/332/936/12h/www.edmunds.com/media/townhall/webxicons/site.gif){kind=small}
Forums
SUVs Toyota RAV4 Toyota RAV4 Throttle Lag
79 messages, Last post on Aug 11, 2009 at 7:38 PM
You are in the Toyota RAV4 Forum. Your Hosts are steve_ & tidester
|
Replying to: mterrell (Jun 26, 2006 5:00 am) This is interesting. Thanks for the info. Should I be looking at something specifically? I don't find much on the Rav4.
|
|
|
Replying to: bob777 (Jul 03, 2006 11:29 am)
|
|
|
Replying to: lir (Aug 18, 2006 4:21 pm) If anyone knows of a solution for this "lag", I would be happy to hear from you.
|
|
|
Replying to: rickco (Aug 20, 2006 6:32 am)
|
|
|
Replying to: lir (Aug 20, 2006 11:55 am) 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.
|
|
|
Replying to: jimd4 (Aug 20, 2006 4:22 pm) |
|
|
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. |
|
|
Replying to: user777 (Aug 20, 2006 10:30 pm) 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.
|
|
|
Replying to: wwest (Aug 21, 2006 10:45 am) 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.
|
|
|
Replying to: user777 (Aug 21, 2006 1:22 pm) 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. |
|
You are here:
Forums
SUVs Toyota RAV4 Toyota RAV4 Throttle Lag
New? Join Now!
Forum Tools
Search Forums
Browse by Vehicle
2011 Toyota RAV4
Browse by Board
Browse by Topic
Today's Chats
