1991*94 240sx: self-diagnostic exhaust gas sensor test mode#2- blink @idle?

[vancouverbc]

In self-diagnostic mode 2 test for oxygen sensor the light is supposed to blink above idle but does yours blink at idle? Should it blink at idle ? I have seen the light on during idle so it is measuring during idle. I think my car used to blink at idle which indicate optimal mix. Im trying to figure out how abnormal it is to be rich at idle.