I am very surprised by the very bad precision of the MMA8451 on the FRDM-KL25Z.
When the board is fixed, the (x,y,z) values of the 1g is changing quite a lot from one read to an other. For example the z value change between 3931 to 3968. It's about 1%. Why have 14bits precision, when the true precision is not good? I am in 2g mode to have the best precision.