Difference Between "d", "b" & "s" Gear In Vitz (1000Cc)

heavyD · May 10, 2011

On 5/10/2011 at 11:59 AM, Sifaan said:

On Sports mode, the car will deliver a better 0-60 time than on normal mode.

Exactly, because the car can now reach peak torque and hp. So why restrict it? Why not leave it in permanent sports mode? The throttle position alone can determine the need of the driver.

Unless S mode only shifts up or down at higher rpms, or increases engine output, it doesn't make sense.

Sifaan · May 10, 2011

On 5/10/2011 at 1:17 PM, Big_D said:

Exactly, because the car can now reach peak torque and hp.

I'm not exactly sure how this works... but now I've referred my engine (PSA EW10J4) specs and it says max torque of 190 NM @ 4100 rpm and max power of 100kW @ 6000 rpm. I don't think the ECU allows it to go upto 6000 rpm even on Sports mode (except of course on 4th gear). Next time I have a clear run I'll take a look at which rpm's it shifts up on Normal, Sports and Manual modes (or for everybody's safety, get my wife to hold a camera while I keep my eyes on the road!)

On 5/10/2011 at 1:17 PM, Big_D said:

So why restrict it? Why not leave it in permanent sports mode?

because then you have more vibration, more noise, more engine wear, more fuel consumption; and most people don't want to pay that price for the benefit of reaching 60mph a little sooner. (autoboxes already take a bashing for being less fuel efficient)

On 5/10/2011 at 1:17 PM, Big_D said:

The throttle position alone can determine the need of the driver.

the throttle position (I presume you mean accelerator pedal position) determines what speed the driver wants to go at; it doesn't determine how fast the car can respond to that need.

On 5/10/2011 at 1:17 PM, Big_D said:

Unless S mode only shifts up or down at higher rpms, or increases engine output, it doesn't make sense.

well, it does increase the effective power of the engine by shifting the power band to the right.

heavyD · May 10, 2011

On 5/10/2011 at 2:21 PM, Sifaan said:

because then you have more vibration, more noise, more engine wear, more fuel consumption; and most people don't want to pay that price for the benefit of reaching 60mph a little sooner. (autoboxes already take a bashing for being less fuel efficient)

But that doesn't mean you have to drive at those rpms all the time.

On 5/10/2011 at 2:21 PM, Sifaan said:

the throttle position (I presume you mean accelerator pedal position) determines what speed the driver wants to go at; it doesn't determine how fast the car can respond to that need.

Yes, but that involves changing throttle response, and I doubt an econobox would have a feature like that.

Sifaan · May 10, 2011

On 5/10/2011 at 3:18 PM, Big_D said:

But that doesn't mean you have to drive at those rpms all the time.

huh? Let's say (taking a simplified case) that an autobox in normal mode will shift up everytime the engine reaches 3000 rpm (and the rpms drop to 1000), and in sports mode will shift up everytime the engine reaches 3600 rpm (and rpms drop to 1200)

Unless you are happy to drive slowly in 1st gear, how can you stop the engine exceeding 3000 rpm if the transmission is permanently in sports mode?

heavyD · May 10, 2011

On 5/10/2011 at 3:49 PM, Sifaan said:

huh? Let's say (taking a simplified case) that an autobox in normal mode will shift up everytime the engine reaches 3000 rpm (and the rpms drop to 1000), and in sports mode will shift up everytime the engine reaches 3600 rpm (and rpms drop to 1200)

Unless you are happy to drive slowly in 1st gear, how can you stop the engine exceeding 3000 rpm if the transmission is permanently in sports mode?

Sorry my bad. When I said permanent sports mode, I didn't mean switching it over and keeping it that way. I meant the car being in that configuration by default from the factory. No rpm cutoff.

virensti · May 10, 2011

aargghh!! confusing!! lol. I just thought it just has a different map on the ECU when you switch it to S.. (it sure would make understanding it alot easier if that were the case )

Sifaan · May 11, 2011

On 5/10/2011 at 4:35 PM, Big_D said:

Sorry my bad. When I said permanent sports mode, I didn't mean switching it over and keeping it that way. I meant the car being in that configuration by default from the factory. No rpm cutoff.

what do you mean?

of course the transmission has to shift up at some point (unless we're talking about a single-gear tesla roadster)

if you mean not having "fixed" cut-offs, I was only using fixed numbers to illustrate the difference; I don't know if it was the case in the past, but I doubt if any modern autobox uses fixed rpms for shifting. e.g. in my manual it says the ECU selects the appropriate gear based on "style of driving, route profile, and vehicle load". Sports mode then "influences" that decision-making to shift up later (and down earlier)

Sifaan · May 11, 2011

On 5/10/2011 at 6:19 PM, virensti said:

aargghh!! confusing!! lol. I just thought it just has a different map on the ECU when you switch it to S.. (it sure would make understanding it alot easier if that were the case )

well... that would be engine in sports mode rather than transmission in sports mode

From an electronics perspective I don't see why they can't build a ECU with 2 maps in the ROM (even if it means a bigger ROM) and have it switch, but mechanically I don't know what the impact would be of the ECU pushing a different set of parameters on an engine that is already running. Since the technology for variable valve timing and lift exists, maybe even that is possible... perhaps the cost of engineering all that is more than it would cost to just have a bigger engine?

heavyD · May 11, 2011

On 5/11/2011 at 1:14 AM, Sifaan said:

what do you mean?

of course the transmission has to shift up at some point (unless we're talking about a single-gear tesla roadster)

if you mean not having "fixed" cut-offs, I was only using fixed numbers to illustrate the difference; I don't know if it was the case in the past, but I doubt if any modern autobox uses fixed rpms for shifting. e.g. in my manual it says the ECU selects the appropriate gear based on "style of driving, route profile, and vehicle load". Sports mode then "influences" that decision-making to shift up later (and down earlier)

Ok, what I understood from your earlier post is that in sport mode, the Vitz just revs higher, to perhaps access peak power and torque. Lets say in normal mode, it revs to a max of 4500 rpm. In sport mode; 6500 rpm.

So, unless a lot of vehicle parameters change when in sport mode (such as more power, shifting at high revs, etc.), and not just the rev limit being raised, I don't see why it was included.

Hope this ends the confusion.

Mernus · May 16, 2011

No body is giving proper answer for this problem.. pls can somebody give correct answer please......

Elvis_Pil · May 16, 2011

On 5/16/2011 at 8:30 AM, Mernus said:

No body is giving proper answer for this problem.. pls can somebody give correct answer please......

Posted 10 May 2011 - 02:21 PM

lol such a simple thing that everyone seems to be confused on. 'S' mode is a hold mode- so basically its for times when you need the car to hold the particular gear ratio its currently in. So in the case of a load drive- you want it to stay in a low gear with high revs and in case of highway drive where performance is needed you'd want it to stay in one particular gear- perhaps around the ratio of a typical 3rd gear. This is the way I'd assume it to be in a CVT box - non CVT should be different.

I'm no expert it automatics though