Distributor / ECU gurus for obd1 cars
 

I'm trying to find out the length of the high time pin A21 (ICM) vs RPM

Here is what I logged with a oscilloscope

These are rough though

PRM - High time - frequency
600rpm - 40ms - 25hz
1100rpm -30ms - 32hz
2000rpm -15ms - 66hz
3000rpm -10ms - 100hz
3500rpm - 8ms - 118hz

The frequecy is an easy calculation RPM*2/60 , but I dont know where ecu is getting the high time from. Any help would be great! Is this a mechanical function or is it calculated inside th ecu?

Re: Distributor / ECU gurus for obd1 cars
 

Bustin out an oscilloscope on ur Dizzy is taking it to a whole new level, what is the reason behind this? Either way I wont be able to help you I just find this interesting.