Hi,
I have been pondering the feature where the 0,0 (top-left) cell of the map is used during cranking (defined as rpm<457). This is the cell corresponding to the lowest rpm, and lowest 'load' value, i.e. lowest TPS value (=closed throttle) or lowest MAP value (=minimum pressure=maximum vacuum=closed throttle also - I hope this is correct). So during cranking it will use the 0,0 cell irrespective of load value, which allows us to specify a small advance value here to ease cranking. However, it appears to me that this is the cell that will also be used during normal idling, where we would normally want somewhat more advance to mimic the normal vacuum advance of a distributer system. So there appears to me to be a conflict here. If the above is the case, would it be more useful to say use cell 0,9 (bottom-left) for the 'special' cranking advance, as this cell represents lowest rpm and highest throttle, which is a point that would rarely be used during normal running? Any comments would be appreciated.
Rich.
Use of 0,0 cell during cranking
Moderators: JeffC, rdoherty, stieg, brentp
Use of 0,0 cell during cranking
Last edited by rbalmford on Fri Jul 06, 2007 10:35 pm, edited 1 time in total.
Hi Rich,
Yes, with TPS this would be a problem, if you needed a special cranking advance and your idle RPM happened to fall in that Bin.
0,0 was chosen more with MAP sensors in mind, where the lowest KPa range is typically reserved for higher RPM, off throttle situations- a KPa you would not see at idle.
So you raise an excellent point and we should make an adjustment. Now- there are two ways we can make this change.
1. Put it in the highest load bin, as you suggested;
2. move it to the 'global controller options'
The drawback with #2 is the global controller options do not change (by design) when you flip between maps.
Thoughts?
Yes, with TPS this would be a problem, if you needed a special cranking advance and your idle RPM happened to fall in that Bin.
0,0 was chosen more with MAP sensors in mind, where the lowest KPa range is typically reserved for higher RPM, off throttle situations- a KPa you would not see at idle.
So you raise an excellent point and we should make an adjustment. Now- there are two ways we can make this change.
1. Put it in the highest load bin, as you suggested;
2. move it to the 'global controller options'
The drawback with #2 is the global controller options do not change (by design) when you flip between maps.
Thoughts?
Thanks for the reply.
Yes I see what you're saying about MAP setups, you wont get full vacuum at idle so it won't use the upper left corner of the map whilst running.
For TPS setups, with the firmware as it is now, one idea to emulate having the cranking cell as the 'high load' cell would be to reverse the TPS calibration table so that closed throttle = 100 and open throttle = 0 (also equivalent to swapping the TPS +ve and gnd feeds), and turn the ignition map 'upside down' to match, so load cell 0 now corresponds to full throttle. This will have the side-effect of a 'backwards' TPS guage!
For a firmware mod, how about having a control bit in the global controller options to select whether cell 0,0 (top-left) or 0,9 (bottom-left) is used for the cranking cell, so MAP or TPS setups could choose the most suitable?
Rich.
Yes I see what you're saying about MAP setups, you wont get full vacuum at idle so it won't use the upper left corner of the map whilst running.
For TPS setups, with the firmware as it is now, one idea to emulate having the cranking cell as the 'high load' cell would be to reverse the TPS calibration table so that closed throttle = 100 and open throttle = 0 (also equivalent to swapping the TPS +ve and gnd feeds), and turn the ignition map 'upside down' to match, so load cell 0 now corresponds to full throttle. This will have the side-effect of a 'backwards' TPS guage!
For a firmware mod, how about having a control bit in the global controller options to select whether cell 0,0 (top-left) or 0,9 (bottom-left) is used for the cranking cell, so MAP or TPS setups could choose the most suitable?
Rich.