Slipping/Non-responsive Throttle in 2007 Sienna
I rented a Sienna this summer for a drive to Canada. It was very responsive to throttle changes. I love it so much I ended buying one. Unfortunately, my purchased vehicle has poor throttle response. The engine revs, but the van does not pick up speed right away. I experience a huge delay in response. Anyone else experience the same problems? Seems like the torque converter is not coupling properly.
Tagged:
0
This discussion has been closed.
Comments
Our 2007 is fine, no hesitation. Plus you feel a difference so this is not normal operation.
I seem to have a very similar problem on my New 2008 Sienna. I waited until I had 1200 miles on it before bringing back to the dealer. Of course, the dealer said there was nothing wrong--ooh what a surprise! The problem I experience is the throttle not responding especially at around 6-8mph. I literally step on the gas for 2" or more and no response (like it is in neutral), then it will lurch up to the next gear. I will also get this reaction when I'm driving along and then coasting, and then I step on the gas with very little response until I press down at least 2 or more inches.
2 experiences I had at the dealer... 1) they told me that since the gas pedal is not electronically controlled and nt by a cable, it has a slower response time (logically this makes no sense to me!) 2) I test drove another 2008 XLE sienna, and it had the exact same response as mine.
I am extremely disappointed that a high-end van like this could have such POOR performance. Every time I get into my car, this is all I think about! I owned a 2001 sienna, which was peppy and responsive.
I'd love to hear from others and their expereinces..........
Here is a link:
http://www.siennaclub.org/forum/index.php?showtopic=15867&st=0&#entry122284
I did this and had no adverse effects, however my 2007 was not hesitating prior to this mod.
My experience is the engine picks up speed right away, but do not feel any acceleration for a second or so. This is especially so when:
1. I go over speed bumps at a slow speed, and press on the throttle after going over the bump,
2. When I lift off the throttle approaching a corner, and pressing on the throttle half way through the corner. Feels like the gear slipped into neutral (engine roars, but no acceleration.
I do not have much clue as to what the computer controls these days. Does anyone know if the computer also controls the torque converter in the 07 Sienna? To me, it feels more like the engine side of the torque converter spins but the torque takes a while to transfer to the drive shaft side of the converter. Wrong spacing? Wrong transmission fluid? Off-spec transmission fluid?
They're set up for peak efficiency, not peak performance. When you let off the throttle before a speed bump, it might shift from, say, 2nd to 3rd, all to save on fuel.
Then you hit the gas and the gear is too tall to accelerate like it would have prior to the speed bump.
The "hesitation" is basically the time it takes for the transmission to shift back to 2nd gear.
If you floor the throttle to compensate, what probably happens is it shifts not once, but twice, and ends up in FIRST gear. So basically the double-shift takes longer, and when it does get in to first gear you notice a sudden surge of acceleration.
Top it off, I bet the ECU dials back the throttle a little to help preserve the transmission, for powertrain longevity. So it shifts, shifts again, then dials back the throttle-by-wire so it doesn't slam in to first gear.
That excaberbates the feeling of hesistaion. You have nothing, nothing...then WOW you get a lot of acceleration.
I would try rolling in to the throttle gradually, so it knows you only want 2nd gear, not 1st. I bet it takes less time to perform that one shift and 1/2 throttle vs. the two shifts at full throttle.
This is pure speculation on my part, of course.
Late in the last century, to conserve fuel, and possibly more importantly, to reduce the heat loading of the ATF, Toyota adopted a sub-standard sized positive displacement gear type ATF pump.
The lower capacity pump could not supply enough volume/pressure to support "HARSH" gear changes, mostly downshifts in this case, so the engineers sat out to eliminate those.
Unsuccessfully so, as it turned out, drivers will do what drivers have always done, ask for GO power at the most inconvient times. So early models, '99 RX300, with/of this "experiment" had a few premature transaxle failures.
So Toyota adopted DBW to "protect the drive train". DBW is being used to delay the onset of engine torque in response to foot pressure on the gas pedal until the downshift, starved for adequate ATF pressure, can be fully completed with the engine at or nearly idling.
Ford, on the new Edge, has adopted a variable displacement ATF pump as a solution to this very same problem. Maybe Toyota will "listen"...??
Ten years and Toyota is still "experimenting".....
The drive-by-wire only support my theory, because it only means Toyota has even more control of what the engine will do (and the driver has less).
I've advanced the timing on my Miata the way lavrishevo descrives, but those days may be behind us as newer cars retard/advance timing on their own, using input from knock sensors for instance.
I'm not sure if you can manually set the timing on the 2GR V6, but I doubt it.
Anyone has any program to flash the ECU of the Sienna to get improved throttle response? If the transmission can take it, the Sienna will be a great sleeper car - with 266 h.p. and a five speed transmission, it can out accelerate a lot of cars. Any tuners out there willing to try it?
Did you observe that? Or does it force a 2nd gear start, even from a dead stop?
When set to 'D', when I approach the corner or the speed bumps, the rpm drops down to close to idle. Pressing on the throttle result in the rpm going up to 2000 or so without instant change in acceleration.
We should do that or at least roll in to the throttle gradually.
DW
Replacing the whole intake does the same thing plus 20% more.. When it comes to power. But understand one thing more HP means more fuel so an intake can work in both ways. Baby the engine you will get better MPG. Stomp on it and you will have more power but worse MPG then before. Personally I think they are well worth the money.
You can always do the same thing for your exhaust system and you will not loose any MPG. Such as high flow cats, larger exhaust pipes, high flow muffler, dual exhaust, headers. Though I doubt they make them for mini-vans.
Full intake could get you 15+ HP, probably at least 10 on a good exhaust setup. 25 horse power is a good gain believe me. Hope this helps, let ne know if you have any other questions.
Have you seen any improvement in the mileage? I think HP is fairly good on Siennas.
2nd Q: Does this voids your warranty?
How much does this cost? Is it DIY yourself job?
FYI... K&N does not make filters for SIenna :mad: Maybe someone else made it.
Second: Babying an engine with an intake should get you 1-2 MPG. How many gallons that is at the end of a tank you will have to calculate. Go to their site and check them out and yes they do make filters for the Sienna.
http://www.knfilters.com/filter_facts.htm
I would suggest for your needs just get a replacement filter not a whole intake.
Third: It has only been half a tank of gas since I added my intake and right now I am noticing between 1-2 MPG increase.
This is what your filter will look like.
This filter is expensive $54. I don't know how much regular Sienna filter would cast.
I seem to recall that someone in the forum said it costs $40 at your local auto shop for intake replacement?
Understand I am in Puerto Rico so prices here can be wacky. The K&N cone filter at pep boys here was 79 bucks. I was not going to pay over 80 with taxes for a filter. They had a another filter there, cone style, that was even bigger and rated just as good as K&N that I purchased for a little over 40 bucks. It was called Power Adder. I had never heard of them before but these type of filters, performance that is, are really all the same. I made the intake myself for my Sedona since no one makes an intake. I did not replace my intake tubing I just removed my airbox and retrofitted the air filter to the end in the stock intake tubing right after the MAF. (mass airflow sensor)
I know sounds a little scary but it took me like 15 min to do and is working great. By the way what year and make is your van?
You're correct that they claim that it lasts longer BUT they say, it has to be cleaned with oil that is sold by them. I'm not sure how much that oil costs.. but is not cheap, I'm sure...
Mine is 2007 Sienna.
Is your OEM filter is also cone?
No mine came with a cheapo fram type air filter and my original K&N filter looked just like yours. Flat and about the same size. The cone was an addition of my own since it is more flowing you just have to retrofit it on your intake tube or get a full intake.
Also said- no one is complaining about it.... :mad:
To me, it feels like my old chevy van did before the transmission failed.
What's a girl to do?
Please keep me posted!
Rivka
http://www-odi.nhtsa.dot.gov/
If enough people complain that they find a pattern, they can force Toyota to fix it.
http://townhall-talk.edmunds.com/direct/view/.f169148/7#MSG7
wwest was saying something about the trans waiting for revs for pressure to build up in order to shift, and there being a longer-than-usual delay when it has to downshift two gears (i.e. 4th to 2nd after a right angle turn).
Well, sorta.
Due to a transaxle design change beginning back in '98 your transaxle is NOT able to complete, QUICKLY complete, a downshift that immediately follows an upshift.
DBW has many positive aspects but in the instance is used as a "cover-up" for the design flaw. In instances when the downshift cannot be quickly completed DBW is used to delay the onset of rising engine torque even though you have re-applied pressure to the gas pedal.
Prior to ~'98 Toyota (all marques..??) automatic transaxles had this same "feature". ATF line pressure was always sustained at a fairly high level using the ATF gear type pump, a fixed relief valve (3000PSI..??) and an accumulator to provide a reserve source of ATF line pressure in situations, brief situations, wherein the ATF pump could not replenish (engine idling) the fluid pressure as fast as it was being "used".
Like your "old" hydraulic power stearing pump the parasitic losses of this technique are a substantial detriment to FE. The PS pressure pump must be sized to provide full functionality even in the worse case. For the power stearing pump this happens to be with the engine idling during parking, say parallel parking. Now, drive straight down the road at 70 MPH and just imagine the volume of hydraulic fluid be pumped only to be bypassed directly back into the sump having reached ~3000PSI.
Same for yesterday's ATF gear pump.
The pressure relief spring/valve has been replaced by a solenoid PWM control system such that the ATF line pressure is now under constant, "real-time", control by the engine/transaxle ECU. "On demand" ATF line pressure, no accumulator needed, nor desired.
So the ATF line pressure can be dropped to some minimum level, maybe even ZERO, when conditions warrant. No detriment to FE when driving along, cruising, constant speed cruising, at 70MPH....2200 RPM. No un-necessary level of ATF pump loading as you climb, accelerate, through the gears, engine ROARING to 5,000 RPM at WOT.
But....
Require a quick downshift immediately after an upshift, an upshift having resulted from a lift throttle, FULL lift throttle event.....Engine RPM has dropped to idle and there is NO reserve ATF line pressure.
(***1) '99 or early '00 F/awd RX300..expect transaxle failure within 50,000 miles.
(***2) Late '00 F/awd RX300...watch out for BURNED ATF.
(***3) '01 and later F/awd RX300..burned and dirty ATF in as little as 40,000 miles. Either drain/flush ATF each 15,000 miles or check ATF condition at each engine oil/filter change.
(***4) RX330...DBW adopted to delay rising engine torque until transaxle shifting can be fully completed. Driver's begin complaining of HAZARDOUS situations when acceleration is unexpectedly, inadvertently, delayed for 1-2 seconds.
(***5) RX350...Firmware revised, driver now being "watched".
Like in my speed bump scenario.
You let off the gas to slow down for a speed bump, then hit the gas after going over it, and you sense that hesitation.