Signals

[Mike Pitts]

I hooked a scope up to my '93 4.3L Vortec HEI ignition 
and later to my 86 Buick GN DIS ignition to compare and 
contrast.  Below is a small bitmap I made to show what I 
found.  The EST signal about 6 ms advanced of the ref 
signal, which I think is about 24 degrees since the total 
waveform at idle was 30 msec wide.  (Gives me ~667 RPM)

((360 deg / 3 cyl fired) / 30 ms) * 6ms = 24 deg ?

Next time I'll hook Diacom up at the same time and have 
a look at what the PCM thinks the timing and RPM are at 
idle.



I also scoped the injector output.  I could see the spike 
from when the injector closed. (What's it called, flyback?)
I was able to verify that my PCM is indeed firing the second 
unused injector driver on pin A9.  I even hooked an injector 
up to it and listened to it click away as the truck engine ran.

I'm tired, see y'all in the morning. 8-)

-Mike

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