Can't really explain very well what i mean but i'll give it ago,

Shouldn't a digital hall effect sensor output its maximum signal voltage despite engine speed unlike an inductive type sensor where the signal voltage increases with engine speed.

In other words i thought it was a fixed output type sensor but just the speed of on/off altered on your scope screen so you change the sweep time to suit.

So when the engine is cranking it appears as if the on/off is slow but when at idle it appears to be faster but it isn't, its just occuring faster.

hope you understand that. Of course this could be a complete load of rubbish and i've got really confused and don't quite understand my self but would like to be corrected/educated eithe way.