Does IS250 Auto Rev-match for you?
08-05-09, 08:06 AM
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Does IS250 Auto Rev-match for you?
Hi all,
I know IS-F has "direct-sport" transmission that rev-matches for you when you downshift, but do you guys know if IS250 has that?
I tried to search but couldn't find the answer.
Thanks!
I know IS-F has "direct-sport" transmission that rev-matches for you when you downshift, but do you guys know if IS250 has that?
I tried to search but couldn't find the answer.
Thanks!
08-05-09, 08:53 AM
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so does it offer some kind of protection when it downshift?
like a torque converter or something?
if not, I guess we shouldn't really downshift with the 250 auto transmission I guess?
like a torque converter or something?
if not, I guess we shouldn't really downshift with the 250 auto transmission I guess?
08-10-09, 11:27 AM
#6
Yeah, you never directly shift the transmission in the ISx50, you simply tell the TCU what you'd like the maximum allowable gear to be... which can sometimes _seem_ like you're downshifting it, but you aren't. You're just limiting the top gear allowed, and assuming it won't hurt the car to do so the TCU will then command a shift down to that gear (or lower, depending on conditions, or not at all if you're actually already in a lower gear)
08-10-09, 12:45 PM
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Thanks guys,
So let's give an example..let's say I am going at 100 km/h (60miles/h for US?)...and let's say I am at 4th gear "downshifting" to 3rd gear..what happens then?
So by downshifting to 3rd gear, my max gear is 3rd....but I am already going at 60 miles/hr....does the TCU downshift to 3rd gear without rev-matching? does that not hurt my engine?
I tested it the other day and what ended up happening is the car jerks a bit while it goes to around 3000-4000 rpm.....but having said that, the car is still pretty smooth....
So let's give an example..let's say I am going at 100 km/h (60miles/h for US?)...and let's say I am at 4th gear "downshifting" to 3rd gear..what happens then?
So by downshifting to 3rd gear, my max gear is 3rd....but I am already going at 60 miles/hr....does the TCU downshift to 3rd gear without rev-matching? does that not hurt my engine?
I tested it the other day and what ended up happening is the car jerks a bit while it goes to around 3000-4000 rpm.....but having said that, the car is still pretty smooth....
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08-10-09, 01:21 PM
#8
yeah, it just shifts to 3rd without rev matching, since 60 mph is still in the "safe" range for 3rd gear.
If you do a search a couple times someone has posted the chart showing what speeds it will allow shifting to for each gear.
It puts more wear on the engine, but so would just flooring the gas where it'd likely downshift automatically too.
Overall I don't bother with the paddles at all outside of driving down the side of a mountain or something where I don't want to melt my brakes.
If you do a search a couple times someone has posted the chart showing what speeds it will allow shifting to for each gear.
It puts more wear on the engine, but so would just flooring the gas where it'd likely downshift automatically too.
Overall I don't bother with the paddles at all outside of driving down the side of a mountain or something where I don't want to melt my brakes.
08-10-09, 01:22 PM
#9
This is about the 4th time I've posted this... 
The S-mode and accompanying paddle shifters are not really "shifters" in that they don't actually shift gears, nor were they designed to - they're merely a mechanism for manually selecting the gear range. Following is Lexus' description of the paddle shifters, taken from the New Car Features section of the FSM:
An S mode indicator light which illuminates when the S mode position is selected and a shift range indicator light, which indicates the range position, have been provided in the combination meter.
Here are the rules by which the different 2IS transmissions allow downshifting:
As you can see, 4th gear allows a top speed of 109, 113, and 109 mph, respectively. You have to be going insanely fast for 4th gear not to be appropriate for the speed at which you're driving. Simply put, if you're going too fast for the gear you want to select, it won't shift.
Javier
The S-mode and accompanying paddle shifters are not really "shifters" in that they don't actually shift gears, nor were they designed to - they're merely a mechanism for manually selecting the gear range. Following is Lexus' description of the paddle shifters, taken from the New Car Features section of the FSM:
By moving the shift lever to the front (“+” position) or to the rear (“-” position), the driver can select the desired shift range position. Also, the shift paddle switch is adopted, which enables changing the shift ranges while the driver is holding the steering wheel. Thus, the driver is able to shift gears with a manual-like feel.
This Multi-mode automatic transmission is designed to allow the driver to switch the gear ranges; not for manually selecting single gears.
An S mode indicator light which illuminates when the S mode position is selected and a shift range indicator light, which indicates the range position, have been provided in the combination meter.
As you can see, 4th gear allows a top speed of 109, 113, and 109 mph, respectively. You have to be going insanely fast for 4th gear not to be appropriate for the speed at which you're driving. Simply put, if you're going too fast for the gear you want to select, it won't shift.
Javier
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