with setRangeSetting you are setting the upper (and lowest) limit. because the value are 10bit (form 0 to 1024), changing the limit also change the precision of the reading...
with limit of 2, a read of 512 (zero)+(512/2=256) is 1G. BUT at limit 8, 1G it is 512+(512/8=64)
(value are just example, they can be wrong. for example, al 16G the sensor can use 16bit precision.