How are S and D modes different?

I'm not talking about the manual aspects of S mode. I use that all the time when driving in the mountains or off road. I'm curious how the automatic shifts are different between the two.

For example, what about if in S4? I realize it wouldn't shift beyond 4th, but compared to D how will the shifts to 2nd, 3rd and 4th differ between the S and D modes, if at all?

My limited experimenting suggests there isn't much difference. Shifts seem to be more or less the same given same road conditions and throttle?

According to the manual (yes, I actually RTFM), AI Shift is on in D and off in S. I assume AI Shift is based on how the AT "learned" to shift based on driver input. What is it learning? In my case, I don't see much difference so either it didn't learn much or I drive in D the way it would normally drive in S.

I will say I don't really have any issue my trans or how it shifts. Most of the time it drives just fine. Might shift to second a bit sooner than ideal but more throttle seems to help there. I'm curious if those who say the trans is crappy are simply crappy drivers and therefore crappy teachers.

Anyway, if anyone can actually explain the difference (not an opinion but any knowledgeable opinion or factual data) that would be great.

 

Sorry, I only have an opinion....

 

Call Toyota. They built the thing, should have all the facts you need.

 

Maybe, but I won't be talking to Toyota, I'd be talking to whatever lackey answers the phone (assuming a real person does). I'm sure there are knowledgeable people here, which is why I posted here.

 

You'll get nothing but opinions here, those opinions may be accurate, but your dead set on facts. Toyota built it, therefore only they would know what the true differences are. Toyota reps are actually very helpful believe it or not, they won't bs answers to you, they will get you to the appropriate person.

 

Fine, then I revise my statement and knowledgeable opinions are welcome.

 

Fact: If you drive in S5 it will never shift to 6th, therefore, less shifting. S5 for me.

 

Some funny replies!

I never looked because I never really use it but is it explained in the manual at all?

 

You answered your own questions already. AI shifting in D uses what it learned and S uses programmed shift points. Easy way to test it to use S6 and mode get on the highway, it probably wont hit 6th untill after 65 MPH. In D it probably shifted to 6th 15 MPH ago, hence all the shifting at wind or hills. D will upshift sooner than S mode more often than not.

I do not have a wonky tranny like some here complain about, but S5 is hard to beat IMO.

 

Not really, other than S mode turns of AI Shift (which isn't overly well explained either).

 

Have you tried R in S mode?

 

Except in my own testing S and D shift to 6th around the same time. I can test more, but there is a section I drive where I turn onto a highway with a slight uphill over a fairly long distance - a mile or more. It almost never shifts to 6th before I crest in D or S mode even when I'm at 65 mph or more. I also never have annoying up/down shifts in D but there are times I do want to lock out 6th or even 5th.

 

No, but have done S in R mode...

 

In your example neither mode should be in 6th. This truck will never shift into 6th going uphill while using anything more than the lightest throttle. If even then. You'd have to crack the throttle to get the tranny to go up a gear.

Level ground cruising while at a steady speed was the example I used.

The difference between the 2 modes isn't drastic, but it definitely is noticeable.

 

Mine feels like I'm driving a "normal" vehicle when driving in S modes. In D, it drives like shit to be honest. Hunting gears, doesn't shift soon enough, holds lower gears after cresting hills. Clunking from 2 to 1. Just doesn't feel right.

 

ECT in D or S6 is very good, should just be normal mode. It probably is the normal rmode and D the crappy Eco map they need to pass EPA. The TSB helped but D still sucks. With ECT on, 6th makes more sense as it shifts there at about 65. The pedal is also remapped and feels a lot more responsive. I came from a Tundra 5.7 that had a super touchy pedal and ECT in the Taco is a lot more normal feeling on hills. S5 is OK but the mileage I'm seeing in ECT is so close it's just not worth screwing around. I just got a 21.8 mpg trip average over about 40 miles mixed highway and back roads. I'll probably mod mine to just default to ECT and be done with it.

All this said, we are not alone. This is becoming typical of new vehicles, at least with V6s. My friend just got a new Honda Pilot, 9 speed auto that shifts constantly, and shuts off when you stop at a light!

 

This has not been my experience and why I'm wondering how the two actually differ with respect to shifting. I haven't spent much time just driving in S5 or S6, but I have not had the issues many talk about in D. I don't have gear hunting, for example. I do see it hold a lower gear a bit after cresting a hill but once I let off the gas a bit it shifts pretty quickly, which is more or less what I'd expect.

The issues I have experienced in D include the stall/stutter that the TSB may address. I'm scheduled for that on Friday. If my AI Shift has learned well, I hope it doesn't destroy that or at least that relearns properly. I've also noticed it shift to higher gears when it's not ideal. For example, driving uphill on a windy road it will shift into 5th or even 6th on corners or slightly flatter sections and then looses speed and I have to give it more gas which cases it to accelerate so I have to let off again and it shifts again. This is when I use S4 so I can hold speed and keep from constant accelerating and decelerating. If the TSB helps here too that would be great, but I think this really is the use case for S mode.

 

So I drove home yesterday and back to work today (28 miles each way) in S6 just to see how it acted differently. To be honest, I don't see any difference. On a flat 45 mph road it still shifted to 6th as soon as I got speed and let off the gas slightly. Same as it does in D. When accelerating onto the freeway it stayed in 4th then 5th until I stopped accelerating and shifted to 6th just as it does when driving in D. If there was any difference in the RPMs when it decided to shift I couldn't tell. I'd say S6 is pointless. S5 might be useful if you really need to lock out 6th but it's never been an issue for me - other than mountain driving. At this point I see no point using S mode for daily driving. After getting the stall TSB applied tomorrow I may think differently if it messes up how it currently drives. While I'm happy to have the stall go away, I hope it doesn't f-up how it drives otherwise.

 

Has anyone shifted to R going down the highway at speed? I saw this on a YT review once. Apparently it's possible so that you can check your trailer connection as you drive as it engages the camera temporarily. So far I have had no balls to try it myself.

 

I've wanted to but afraid of jacking things up. One would assume there would be some sort of lockout to prevent shifting into R at speed but I'm not going to test that. If so, at what speed does such a lockout engage? I would hope anything over a few MPH would lockout R.