Originally Posted by
5DIGITS
On a side note:
The above is sensitive to where the MAP and RPM breakpoints are set and why adaptive control typically becomes unstable with 3bar and higher MAP sensors, due to the break-point definitions and poor resolution.
Because the preceding short term trim appears in the current cylinder PW calculation, any fluctuation in MAP or RPM causes corruption as the adaptive moves to a different cell location in the array.
This results in adaptive 'hunting' and the values never stabilize/normalize and repeatedly learn up and down as the car is driven and bounce between cells.
For any car running 22psi or less on the street, I have always recommended a 2.5 bar MAP and careful selection of the MAP/RPM array breakpoints to minimize these instabilities.
In short, simply converting the MAP values to a 2.5, 3.0, or higher MAP sensor doesn't won't work well if the hardware (head, cam, intake,etc..) have all altered the flow and tuning of the 'system'.
Also, the delta MAP inhibitors need to be adjusted to eliminate any transient throttle/MAP fueling from being included into the adaptive fuel calculation.
This will unfortunately slow the adaptive fuel updates BUT will help stabilize the final learned values by reducing transient fuel corruption.
My previous project using a 2.5 Bar sensor took a week of evening work and data collection just to select where the breakpoints and transient inhibitors needed to be set for 'centered' stable learning.
This will all reduce the cylinder to cylinder variations discussed above while improving the overall stability of the system.