Steptronic-Transmission Performance Fuel Maps
10-19-2005, 06:15 PM
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Hi Friends:
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
10-19-2005, 07:22 PM
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Interesting... now can you read the SMG one and tell me how it choses XS? 
Ah ah Ah I cant say it I cant... I must be nice... Nooooooooooooo I gotta say it.
Should have gotten SMG!
Originally Posted by donv' date='Oct 19 2005, 07:15 PM
I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
[snapback]186365[/snapback]
Ah ah Ah I cant say it I cant... I must be nice... Nooooooooooooo I gotta say it.
Should have gotten SMG!
10-19-2005, 07:27 PM
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Originally Posted by EBMCS03' date='Oct 19 2005, 10:22 PM
Interesting... now can you read the SMG one and tell me how it choses XS??
[quote name='donv' date='Oct 19 2005, 07:15 PM']I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
[quote name='donv' date='Oct 19 2005, 07:15 PM']I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
[snapback]186365[/snapback]
Ah ah Ah I cant say it I cant... I must be nice... Nooooooooooooo I gotta say it.
Should have gotten SMG!
[snapback]186385[/snapback]
[/quote]Thanks. I'll read the SMG write-up when I get an SMG. I sometimes have 2nd thoughts, but I wanted the simplicity of the Step this time around. I am good with the Step for now. In the future, I don't know. And, I might have to shift the SMG manually for better MPG also. The SMG probably will be even more refined in a few years. I'll probably/maybe choose the SMG then.
10-19-2005, 07:31 PM
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Originally Posted by donv' date='Oct 19 2005, 08:27 PM
The SMG probably will be even more refined in a few years.
[snapback]186388[/snapback]
10-20-2005, 02:30 AM
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Originally Posted by donv' date='Oct 20 2005, 03:15 AM
Hi Friends:
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
[snapback]186365[/snapback]
I think it does not matter to actually know in which map we are driving as the algorithm must be, as already said, much more complex than:
...
if rev>3800 and <4800 and (highthrottledepression=true or highlateralacc=true or highbrakepushing=true) and currentgear=3 then
shiftup();
endif
...
I think it may for instance taken into consideration, the recent history of driving too make a smooth transition between the maps but I have no technical information and I rather doubt that the manufacter gearbox controller program is a free software! <_<
So to sum-up, I just observed a certain behaviour of the gear box, which as my opinion, correspond to the existance of several maps. For the rest, I simply don't care as it is providing a shifting I like. I'm not a professional race driver and I'm pretty sure that an SMG would not allow me to have better performances as what the controller of the steptronic is doing for me in DS mode.
However, if someone has a reliable techincal information about the detailled functionning of the control software, I'm anyway curious to see how the control is actually performed.
Fred
10-20-2005, 08:36 AM
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Originally Posted by DINAN530i' date='Oct 20 2005, 03:03 AM
3/4 pedal compression kicks it into XS
[snapback]186439[/snapback]
10-20-2005, 08:38 AM
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Originally Posted by fred1976' date='Oct 20 2005, 05:30 AM
[quote name='donv' date='Oct 20 2005, 03:15 AM']Hi Friends:
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
Earlier I inquired about a write-up that describes much of the functioning of the Steptronic transmission. Stream referred me to it--found here: Steptronic Write-Up.
I read the write-up, and, to me, the important performance-related points, and some general ones, are as follows. The Steptronic transmission's adaptive transmission control system "can choose" from 4 fuel maps--two pertaining to D (comfort) mode and 2 pertaining to DS/manual (M) modes. For the DS/M modes, the maps are S (sport) and XS (extreme sport). For the D mode, the maps are XE (extreme economy) and E (economy).
The modes are selected by three types of adaptation-to-driver sensors-- the kick-fast, cornering-direction, and brake-evaluation sensors. I'll discuss only kick fast as the other sensors have similar effects. And, I'll discuss only the DS/M modes because the D mode works similarly but in relation to different maps.
The 5-Series driver-adaptation process starts over after each complete stop. If one depresses the accelerator pedal far enough and quickly enough starting from a complete stop, then the XS mode is supposed to be selected--which, of course, is good if one wants to accelerate as rapidly as possible given the pedal depression. I could not infer how far or how fast the pedal must be depressed in order to activate the XS map.
I assume that if one started in DS or M, but did not depress the pedal far enough or quickly enough to engage XS at the outset, then XS would be selected if the pedal was pushed quickly to the floor subsequently. But, I do not know whether or not my supposition is true. The system would be poorly conceived if my supposition is not true. Similarly, I could not infer how extreme cornering or braking would have to be to force selection of XS.
I have not attempted to confirm that the system works as advertized. fred1976 beleives that it does given his limited tests. Personally, I get better gas mileage (about 16.5 MPG with only a small amount of freeway driving) while in the DS/M modes with the S map selected. Apparently, I am able to do better using lower gears more frequently and selecting my own shift points when I am not satisfied with the 545i's DS shifting.
[snapback]186365[/snapback]
I think it does not matter to actually know in which map we are driving as the algorithm must be, as already said, much more complex than:
...
if rev>3800 and <4800 and (highthrottledepression=true or highlateralacc=true or highbrakepushing=true) and currentgear=3 then
shiftup();
endif
...
I think it may for instance taken into consideration, the recent history of driving too make a smooth transition between the maps but I have no technical information and I rather doubt that the manufacter gearbox controller program is a free software! <_<
So to sum-up, I just observed a certain behaviour of the gear box, which as my opinion, correspond to the existance of several maps. For the rest, I simply don't care as it is providing a shifting I like. I'm not a professional race driver and I'm pretty sure that an SMG would not allow me to have better performances as what the controller of the steptronic is doing for me in DS mode.
However, if someone has a reliable techincal information about the detailled functionning of the control software, I'm anyway curious to see how the control is actually performed.
Fred
[snapback]186470[/snapback]
[/quote]I would like to know more too.
10-20-2005, 01:37 PM
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Originally Posted by donv' date='Oct 20 2005, 11:36 AM
[quote name='DINAN530i' date='Oct 20 2005, 03:03 AM']3/4 pedal compression kicks it into XS
[snapback]186439[/snapback]
[snapback]186643[/snapback]
[/quote]Yes or from a stand still 3/4 pressue kicks it into XS either moving or stopped
10-20-2005, 03:19 PM
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Originally Posted by DINAN530i' date='Oct 20 2005, 04:37 PM
[quote name='donv' date='Oct 20 2005, 11:36 AM'][quote name='DINAN530i' date='Oct 20 2005, 03:03 AM']3/4 pedal compression kicks it into XS
[snapback]186439[/snapback]
[snapback]186643[/snapback]
[/quote]Yes or from a stand still 3/4 pressue kicks it into XS either moving or stopped
[snapback]186768[/snapback]
[/quote]Thanks much. I may have another question, but I need to reread first.
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