"D" mode vs. "S" mode Automatic Transmission
06-26-06, 10:12 AM
#17
Driver
Thread Starter
Join Date: Jun 2006
Location: CA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by IS-Jim
OK. this is a run down on how the S mode works:
If you have the tranny in "S" it allows you to select what gear you want to be in 1-6.
If you keep it in 6th then the tranny will automatically use gears 1-6 ( same thing as "D" mode)
if you keep it in 5th gear then the tranny will automaically use gears 1-5 and will hit the rev imiter at the end of gear 5 instead of shifting past it.
If you keep it in 4th gear then the tranny will automatically use gears 1-4 and will hit the rev limiter at the end of gear 4 instead of shifting past it
If you keep it in 3rd gear then the tranny will automatically use gears 1-3 and will hit the rev limiter at the end of gear 3 instead of shifting past it
If you keep it in 2nd gear then the tranny will automatically use gears 1-2 and will hit the rev limiter at the end of gear 2 instead of shifting past it
If you keep it in 1st gear then the tranny will only stay in first gear....
So.. that is why having it in "S" mode and 6th gear is the same as having it in "D"-- it is using all 6 gears automatically.
So why have it in "S" and 6th,,, that way you can shift down quicker than having to move the gear lever over and then shifting...
I hope that helps you some.. So really to answer you question is is ok to drive in "s" mode and 6th gear.
If you have the tranny in "S" it allows you to select what gear you want to be in 1-6.
If you keep it in 6th then the tranny will automatically use gears 1-6 ( same thing as "D" mode)
if you keep it in 5th gear then the tranny will automaically use gears 1-5 and will hit the rev imiter at the end of gear 5 instead of shifting past it.
If you keep it in 4th gear then the tranny will automatically use gears 1-4 and will hit the rev limiter at the end of gear 4 instead of shifting past it
If you keep it in 3rd gear then the tranny will automatically use gears 1-3 and will hit the rev limiter at the end of gear 3 instead of shifting past it
If you keep it in 2nd gear then the tranny will automatically use gears 1-2 and will hit the rev limiter at the end of gear 2 instead of shifting past it
If you keep it in 1st gear then the tranny will only stay in first gear....
So.. that is why having it in "S" mode and 6th gear is the same as having it in "D"-- it is using all 6 gears automatically.
So why have it in "S" and 6th,,, that way you can shift down quicker than having to move the gear lever over and then shifting...
I hope that helps you some.. So really to answer you question is is ok to drive in "s" mode and 6th gear.
IS-Jim, I agree with you, but you were agreeing with jlin101...did you read his post? He says, that even if he leaves it in 6th gear in "S" mode, he NEEDS to shift manually using the paddles if he stops at a light (because it shifts to 1st).
I am assuming you read his post wrong, because I am in agreement. If this is the case, then jlin101, you need to check with your dealer why this is happening...
06-26-06, 10:21 AM
#18
Driver
Thread Starter
Join Date: Jun 2006
Location: CA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by monkeyfarm
Safe? Are you kidding? Do you actually think Lexus would design a car with a mode of operation they considered unsafe? Oi vei...
The only difference between S mode and D mode is exactly what the manual states... in S mode, AI-SHIFT is turned off. That means it's left up to the driver to downshift when they want to (although obviously the car will still downshift when you're coming to a stop or if you hammer the throttle). Where as in D mode in ECT PWR, downshift will occur under heavy breaking when the computer has decided some engine braking would be a good idea.
It's incredibly easy for you to see this on your own. Go out for a drive. Put the car in D mode with ECT PWR on. Floor it until you hit reasonble speed, then hammer the brakes. As you slow, the car will downshift at noticeably higher rpm that it would without ECT PWR on to provide engine braking and to select the correct gear for a potential corner you might be about to enter.
If you then switch to S mode and leave ECT PWR on and do the same thing, the car won't downshift. AI SHIFT has been disabled... i.e. it's up to you to downshift if you want to.
That's it... those are the only differences. Now stop sweating over something that isn't a concern.
The only difference between S mode and D mode is exactly what the manual states... in S mode, AI-SHIFT is turned off. That means it's left up to the driver to downshift when they want to (although obviously the car will still downshift when you're coming to a stop or if you hammer the throttle). Where as in D mode in ECT PWR, downshift will occur under heavy breaking when the computer has decided some engine braking would be a good idea.
It's incredibly easy for you to see this on your own. Go out for a drive. Put the car in D mode with ECT PWR on. Floor it until you hit reasonble speed, then hammer the brakes. As you slow, the car will downshift at noticeably higher rpm that it would without ECT PWR on to provide engine braking and to select the correct gear for a potential corner you might be about to enter.
If you then switch to S mode and leave ECT PWR on and do the same thing, the car won't downshift. AI SHIFT has been disabled... i.e. it's up to you to downshift if you want to.
That's it... those are the only differences. Now stop sweating over something that isn't a concern.
As I mentioned several times (and in other posts), I do agree that is APPEARS that it operates the same way as "D" mode, but the manual appears to state things differently, and my naked eye might not be able to see the long term effects.
And I can't agree with your blanket statement of "Do you actually think Lexus would design a car with a mode of operation they considered unsafe..." As it applies to this post, do you think there's a chance someone with an IS250 MT can mess up their transmission? Will the computer auto shift their gears if they are redlining in 1st? I don't think so. I think the car will shift only when the driver presses the clutch and manually shifts. Does this mean that because it's a Lexus it will last just as long as an auto? I also don't think so. I think there are plenty of factors that can go into how a driver can affect the life of a vehicle, which is the essence of my post...
06-26-06, 10:25 AM
#19
Driver
Join Date: May 2006
Location: Naples, Florida
Posts: 130
Likes: 0
Received 0 Likes
on
0 Posts
After reading it like 5 times I really dont' know what he means vs what he actually typed.. but if it doesnt' work like the way I described then there might be a problem. hehe 
06-26-06, 10:31 AM
#20
Driver
Join Date: May 2006
Location: Naples, Florida
Posts: 130
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by SuperLexy
monkeyfarm,
As I mentioned several times (and in other posts), I do agree that is APPEARS that it operates the same way as "D" mode, but the manual appears to state things differently, and my naked eye might not be able to see the long term effects.
As I mentioned several times (and in other posts), I do agree that is APPEARS that it operates the same way as "D" mode, but the manual appears to state things differently, and my naked eye might not be able to see the long term effects.
I can assure you that driving in "S" mode and 6th gear will do your tranny no more harm than driving in "D" mode. I am not a vehicle engineer but I am a Test Car Driver for Toyota/Lexus and have seen these trannies go for many of miles... they are pretty much built like tanks...
06-26-06, 10:33 AM
#21
Lexus Champion
Join Date: May 2006
Location: FL
Posts: 1,600
Likes: 0
Received 0 Likes
on
0 Posts
If you guys wanted to shift your own gears, why didn't you just buy the car with a manual tranny? 
Real men use the 3rd pedal
I don't know how it would be any different. You're using the same 6th gear. If using 6th gear in "S" mode caused damage or premature wear to the transmission, I seriously doubt that the guys that designed the car would've allowed the car to be driven in those circumstances. I think you're worried about nothing.
Real men use the 3rd pedal
Originally Posted by SuperLexy
monkeyfarm, I'm not saying it's unsafe in a way that my car is on the verge of dying. I'm talking long-term effects here. There is a point to using AI-SHIFT and there's a point to why the Lexus owner's manual recommends to drive in "D" mode. So, it's natural for me to ask if it's OK to drive "normally" in "S" mode (i.e. without using the paddles/shifter). I'm sure anyone else who wants to drive in "S" mode forever would benefit from knowing this, as well...
Last edited by ff_; 06-26-06 at 10:38 AM.
06-26-06, 12:02 PM
#22
Driver
Thread Starter
Join Date: Jun 2006
Location: CA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by ff_
If you guys wanted to shift your own gears, why didn't you just buy the car with a manual tranny?
Real men use the 3rd pedal
I don't know how it would be any different. You're using the same 6th gear. If using 6th gear in "S" mode caused damage or premature wear to the transmission, I seriously doubt that the guys that designed the car would've allowed the car to be driven in those circumstances. I think you're worried about nothing.
Real men use the 3rd pedal
I don't know how it would be any different. You're using the same 6th gear. If using 6th gear in "S" mode caused damage or premature wear to the transmission, I seriously doubt that the guys that designed the car would've allowed the car to be driven in those circumstances. I think you're worried about nothing.
Oh well...until someone comes up with something definitive, I'll keep "S" mode-ing it, because it's a lot more fun to drive that way.
And ff, I definitely did want a manual tranny, but unfortunately the 350 didn't come with it. I've been driving manuals all my life and it was definitely somewhat of a downer to only have an auto available. I was trying to get the "best of both worlds" with this tranny. Anyway, the fact that it doesn't come with a manual is still a very small complaint for me in the bigger picture of loving every other aspect of this vehicle...ROCKS.
08-16-06, 09:06 AM
#23
Lead Lap
Join Date: May 2006
Location: Ottawa,Ontario
Posts: 688
Likes: 0
Received 0 Likes
on
0 Posts
Anyone else tried to see if our automatic cars downshifted differently by it's own (AI-Shift) when in D compared to S mode and leave it in 6 gear?
I just read this thread today and will definitely try to notice next time I drive the Lexy.
I just read this thread today and will definitely try to notice next time I drive the Lexy.
Last edited by phatboyc; 08-16-06 at 12:51 PM.
08-16-06, 09:20 AM
#24
Lexus Test Driver
When I drive with D mode...IS goes smoothly...very smooth(too smooth sometime feels like under power especially up hill) S mode hold the top gear at 4 and if you push the gas pedal the gear will automaticlly shift down and the power kicks in... Still you should also switch the PWD ECT on to get the full power of the V6
08-16-06, 10:38 AM
#25
You can't leave the gear selector in S and 6th gear. As soon as the car comes to a stop, the transmission automatically shifts down to 1st, then you have to upshift with the paddles. To me, it's a drag to drive around in S mode on a regular basis; just leave it in D, PWR mode and the transmission ought to downshift with just a tap of the gas pedal.
08-16-06, 11:36 AM
#26
Driver
Thread Starter
Join Date: Jun 2006
Location: CA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
this is how all sport shift autos work, my brothers TSX does this somehwhat bit it jumps to 3rd before going to 1 on a stop if im stopping from 5th geear. Whys it a drag, personally it would be a drag if the car didnt shift to 1 at a stop and youd have to tap down 6 to 5 to 4 to 3 to 2 to 1 ever stop, and if you forget you would start to move a car in 6th gear and stall the engine. That is how they all work, nothing is wrong or badly designed
Ok, it seems like most people are not understanding this thread (some are, obviously)...it's really not complicated, though...
Let me reiterate in the clearest way possible:It *appears* to the naked eye that S-mode in 6th gear and D-mode (regular automatic) operate identically in nature.
HOWEVER...
according to p99-100 of the owners manual, there is a clear distinction that D-mode activates something called "AI-SHIFT" (probably "artificial intelligence shift"), which apparently does not occur in S-mode-6th-gear.
The question is, "What is the difference?" and, "Is there *any* negative--whether mechanically or performance-wise--to running the car exclusively in S-mode-6th-gear?"
This thread is probably best answered by a Lexus IS Engineer, which is why we can't get any definitive answers...it's no biggie.
At this point, since the thread is old, I vote to throw out the speculation...it's all already been said. Let's wait to hear something authoritative...
I'd be happy to hear how people are experiencing any differences in real life testing, though (phatboyc, etc)...
08-16-06, 12:19 PM
#27
My question is (1) whether anyone knows--definitively--what the difference is between driving in "D" mode vs driving in "S" mode and leaving it in 6th gear; and (2) whether it hurts the tranny to drive in "S" mode in 6th gear? Please try to limit the speculation, as I'm sure others will also benefit from the factual knowledge that frequently surfaces in this awesome forum.
(2) You really only have a gear hold ability in the IS. Therefore, putting it in 6th doesn't hurt the tranny at all, as the car still shifts as it pleases. If you hold the gear in a selection lower than your cars engine speed is going, it will hit the rev limiter.
It also says on p.100 that "AI-SHIFT" mode only works when the shifter is in "D", but then how does it know how to shift automatically when in 6th gear in "S" mode?
From Lexus:
Think of Artificial Intelligence Shift as a gearbox that can read your mind. When you want relax and just cruise, it gives you smooth automatic gearchanges. When you want to press on, the changes become quicker and crisper. So how can it predict your mood? Sensors monitor the movement of the accelerator pedal, the car's speed and the road conditions. Then, using complex algorithms, the system determines your intent and makes intelligent choices about gear selection. It even changes down intuitively when you are going downhill to give you more engine braking.
http://www.lexus-europe.com/technolo....asp?model=All
08-16-06, 12:53 PM
#28
i see no difference b/t the car deciding to shift, or the driver deciding to shift when in the end the same mechanical component does the shifting, therefore there is no difference b/t the two, the drive just has more control in one instance. It can be argued when you use S mode you can get better mileage over D mode since you can get into higher cruising gears earlier than D mode can
08-16-06, 05:23 PM
#29
Driver
Thread Starter
Join Date: Jun 2006
Location: CA
Posts: 142
Likes: 0
Received 0 Likes
on
0 Posts
From Lexus:
Think of Artificial Intelligence Shift as a gearbox that can read your mind. When you want relax and just cruise, it gives you smooth automatic gearchanges. When you want to press on, the changes become quicker and crisper. So how can it predict your mood? Sensors monitor the movement of the accelerator pedal, the car's speed and the road conditions. Then, using complex algorithms, the system determines your intent and makes intelligent choices about gear selection. It even changes down intuitively when you are going downhill to give you more engine braking.
http://www.lexus-europe.com/technolo....asp?model=All
That explains things really well. In my first post "hurting the tranny" was a little strong verbiage. I was more intersted in knowing how the differences would affect the IS at any level...this is great info.
Heh, leave it to the europeans to do it right...
08-16-06, 07:12 PM
#30
Here's the single best post in this thread thus far...great find, Shinobi-X
That explains things really well. In my first post "hurting the tranny" was a little strong verbiage. I was more intersted in knowing how the differences would affect the IS at any level...this is great info.
Heh, leave it to the europeans to do it right...
That explains things really well. In my first post "hurting the tranny" was a little strong verbiage. I was more intersted in knowing how the differences would affect the IS at any level...this is great info.
Heh, leave it to the europeans to do it right...
Does AI make enough of a difference to be noticable, or is too subtle of a change? Hard to say, but you could probably track shift points/revs at different speeds based on multiple runs over the same road. I'll take their word that the AI works as advertised. Oh, similar to the IS, the Catera also had a sport (power mode), which I used quite frequently. I'm not sure that it was a contributing factor but the transmission failed at 80k miles and then two more times within the next 10k miles. I'm confident that the Lexus transmission is better built, but I think that if you run the car in power mode, you have to wonder if it doesn't create more wear and tear on the transmission.
