on my secs I use the water injection to trigger a timeing rely that keeps on for 6 minuts.
It was for a homebuild charge cooler kit , (Build it for fun, and did not work ).

Anyway there are 2 parameters that trigger the water injection;
Boost level and air temp .

There is a 0-100% reading at the secs monitor but it's just a read out, not a controler device!