GM LS D585 Coil Pack Oscilloscope Trace Running without ECM - What am I looking at? Auto Fire ?

waid786

New Member
I managed to make a single D585 coil work without a computer and with a carbuetor by installing a hall sensor inside a Ford 302 Distributor. The hall sensor sends a 12V square wave directly to the Pin C of the coil. I have been doing some testing and have about an hour on the motor and so far so good. Idle is smooth and no issues even at 5,500 rpm. Looking the oscilloscope trace, I am seeing about 2ms dwell at 4,500 RPM. However, I see almost 10ms dwell at idle.

I know D585 likes to auto fire with too much dwell. What is the peak I am seeing between the 10ms dwell at Idle? Is the coil firing when it reaches maximum dwell at 5ms?

I am not seeing any iralic idle and very smooth.

Thank you,
 

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