This document describes a method for adapting line pressure of a continuously variable transmission (CVT). The determination on how to adapt line pressure is based on the learning of commanded and actual line pressure errors by monitoring the primary 8 and secondary 9 pulley pressure sensor with line pressure increase. To compensate for these pressure errors, it allows the overall reduction in line pressure offset to improve efficiency. The line pressure errors can be learned when the line pressure is stable (e.g., vehicle is not moving), the transmission hydraulic pump 1 provides the constant flow to the hydraulic circuits, and the variator 10 does not ratio. By setting the line pressure solenoid 4 to a few calibraratable pressure values, which moves the line pressure valve 7, and reading both primary and secondary pressure sensor while opening both primary 5 and secondary 6 pulley valve wide via controlling primary solenoid 3 and secondary solenoid 2, the learning of the pressure error between the commanded and actual line pressure can be achieved. To ensure that the line pressure reaches a stable pressure at each pressure step during the learn process, a calibratable delay timer can be used before the measurement starts. In order to reduce variation of pressure in the calculation, an average of the pulley pressure measurements over a period of time can also be used. The line pressure error is the difference between the commanded and actual line pressure. To get even more accurate in line pressure, the converging method can be applied by adding the previous learned value of line pressure error to the commanded line for the next line pressure error learn cycle. The difference between the commanded line and the actual line pressure plus the previous learned line pressure error becomes the new line pressure error.
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