2011 Sienna Towing - OD or Economy?

[Zector]

I know some models say turn off the overdrive when pulling. Should I turn off the feul economy light thingie in the dash? It doesn't seem to make any difference aside from telling me when im light on the pedal with normal driving and towing.

Aside from the normal taken it easy when pulling, should i turn that green light off, or another OD type option i should know about to toggle off?

[shineysideup]

I know some models say turn off the overdrive when pulling. Should I turn off the feul economy light thingie in the dash? It doesn't seem to make any difference aside from telling me when im light on the pedal with normal driving and towing.

Aside from the normal taken it easy when pulling, should i turn that green light off, or another OD type option i should know about to toggle off?

You don't want your van to be hunting for gears constantly or having the torque converter unlocking all the time. This is very subtle to see, only a couple hundred rpm's (e.g. 2000 rpm's vs. 2200 rpm's) My 04 sienna doesn't have a o.d. lock out button but my 98 camry does...

[Zector]

What do you mean torque converter locking unlocking all the time? It stays in 5th gear at 55-60mph @ ~2000 rpm no problem. When it is in gear i notice a little bump with rpm up and down, both in normal driving and when towing. I mean sometimes stays a little higher rpm, and comes down a small amount (not shifting a gear) on flat or light downhills, I guess this would be the torque converter. Would it hurt it running on the higher side, which it does mostly? It doesn't jump much at all maybe on big headwind or hills, and rarely downshifts just on big hills at these speeds.

What speed / gear do most run in? Should i set it in a gear and leave it till a big hill? What would be best for the tranny/engine?

[brian_bp]

What do you mean torque converter locking unlocking all the time? It stays in 5th gear at 55-60mph @ ~2000 rpm no problem. When it is in gear i notice a little bump with rpm up and down, both in normal driving and when towing. I mean sometimes stays a little higher rpm, and comes down a small amount (not shifting a gear) on flat or light downhills, I guess this would be the torque converter.

Right - if the engine speed changes without the road speed changing, then the transmission ratio has changed. If it does that without shifting gears, then the torque converter drive ratio is changing, which means that it is unlocked.

Would it hurt it running on the higher side, which it does mostly? It doesn't jump much at all maybe on big headwind or hills, and rarely downshifts just on big hills at these speeds.

Downshifts are fine where appropriate, and the torque converter unlocks for good reason so that's not necessarily a problem, but every moment it is unlocked it is slipping, which wastes fuel and turns it into heat in the transmission. The idea is to keep the torque converter locked up as much as possible whenever moving at reasonably constant speed, other than the very low speeds requiring use of the lower gears.

[shineysideup]

What do you mean torque converter locking unlocking all the time? It stays in 5th gear at 55-60mph @ ~2000 rpm no problem. When it is in gear i notice a little bump with rpm up and down, both in normal driving and when towing. I mean sometimes stays a little higher rpm, and comes down a small amount (not shifting a gear) on flat or light downhills, I guess this would be the torque converter.

Right - if the engine speed changes without the road speed changing, then the transmission ratio has changed. If it does that without shifting gears, then the torque converter drive ratio is changing, which means that it is unlocked.

Would it hurt it running on the higher side, which it does mostly? It doesn't jump much at all maybe on big headwind or hills, and rarely downshifts just on big hills at these speeds.

Downshifts are fine where appropriate, and the torque converter unlocks for good reason so that's not necessarily a problem, but every moment it is unlocked it is slipping, which wastes fuel and turns it into heat in the transmission. The idea is to keep the torque converter locked up as much as possible whenever moving at reasonably constant speed, other than the very low speeds requiring use of the lower gears.

My point is and I believe Brian is saying the same thing, you don't want the torque converter locking and unlocking constantly nor do you want the van hunting for gears continually. When my van downshifts I will sometimes lock it into that gear - like when traveling up a long hill. I know the vehicle well enough to determine that it would try and slip back into a taller gear just to decide seconds later it was better off in the other gear... :P

[brian_bp]

My point is and I believe Brian is saying the same thing, you don't want the torque converter locking and unlocking constantly nor do you want the van hunting for gears continually. When my van downshifts I will sometimes lock it into that gear - like when traveling up a long hill. I know the vehicle well enough to determine that it would try and slip back into a taller gear just to decide seconds later it was better off in the other gear... :P

Yes, well put.

Not only do you not want it shifting a lot - every shift is wear and tear - but you also don't want to have the torque converter to spend more time unlocked than necessary, and in situations such as those described above the lower gear may allow the torque converter to stay locked up.

[Zector]

So when in doubt, go into a lower gear, for higher rpm's and the torque to converter lock up?

What is a normal rpm range i should go for in normal conditions with trailer (no hills etc)? would 2500-3000 be excessive going long hauls on the v6? it tends to sit at around 2000 with cruise control, like i mentioned and does not hunt gears, but sometimes locks/unlocks the TC to adjust to conditions ie winds light hills. the floor does warm up some.

Does the S lock the TC in higher gears? I read some trannies lock it 4th and higher.

Just trying to tailor my driving for the big trip this weekend.

Maybe a new stickie thread for input on best driving practices when towing would be in order?

Thanks for all input!

[p220sigman]

It depends a lot on where you are driving. Down here in sunny flat Florida, I usually just put it in D like always. It doesn't do any hunting or a lot of shifting. If I drove in any area where there are hills, I would probably use 4. All the shifting creates heat and heat is what you are wanting to avoid in the transmission. It is the quickest way to kill one.

[tcp]

I have a 2005 with the 3.3l and 5speed transmission. I usually tow in 4. The only time I would let it to get into 5th gear is on a long gentle downhill where the hill acceleration counteracts the wind drag from the trailer (3350lb factory optioned dry weight, 4000lb loaded Funfinder 189FDS). I tow everywhere in western Canada. Heading to southern BC (Kikomun creek provincial park) this weekend and then 2 weeks in the Okanagan valley at the end of July(bear creek provincial park).

Our trips include several passes through the rockies and I've never held up traffic in them. I'm often stuck behind old motorhomes or pickup trucks towing behemoth trailers, where i would have to wind out the sienna to get by them (not really willing to abuse it to save a few minutes). I use a carchip (www.carchip.com) to log engine/vehicle parameters while towing and can graph useful info over the trips I take. My maximum rpm so far, with the trailer attached is 4600rpm and the usual engine speeds are are 2500-3000. The torque converter definitely locks up with the transmission set to 4.

I would imagine the 3.5l with the 6speed transmission (U660E/F) would do very well towing. Keeping the engine spinning .

This might be of interest:

http://www.youtube.com/watch?v=fAZeCSZIU2g

[brian_bp]

I'm surprised that I didn't catch this before, but "overdrive" doesn't mean much in this discussion. Overdrive just means a reduction gear ratio of less than one (so the transmission output is faster than the input), and the 1:1 ratio isn't some magic number that makes any difference to anything. All that matters is how many times the engine needs to turn per unit of distance travelled. In the 2011 transmission, both 5th and 6th gears happen to have overdrive ratios.

I think when people talk about taking it out of overdrive, they just mean moving the gear selection lever to keep the transmission from using the highest available gear. To get roughly the same effect on engine speed as selecting "4" in a second-generation Sienna (preventing the use of 5th gear), the driver of a 2001 Sienna would need to select "S4" (preventing the use of both 5th gear and sixth gear). Even though the two transmissions have different 4th gear ratios, they also have different final drive ratios and tire sizes, and the net effect of all three factors is that the 2011 revs 7% faster in 4th than the 2004.

Does the S lock the TC in higher gears? I read some trannies lock it 4th and higher.

I assume, based on other discussions, that the 2011 "S" mode selections are identical in behaviour to the 2004-2010 selections... except that there is one more gear and thus one more selection.

I don't think the torque converter lockup behaviour is affected by whether the current gear is the result of fully automatic ("D") operation or more manual selection (such as the 2011 "S" mode). The second-generation transmission certainly locks up in at least 5th and 4th gears, and perhaps lower. It seems reasonable to assume that the 2011 transmission also locks up in at least two gears (6th and 5th), likely more, possibly every gear.

Grade Logic might be the exception: I assume that when Grade Logic triggers a downshift for engine braking, the torque converter is locked up, even if it might not lock up if the gear had been reached for other reasons.