Hi,
I'm currently building a digital tach for my 94 CX (D15b7 Cnd) and I'm somewhat confused about the signal coming off of the signal wire.
I had originally assumed that the signal would look like the picture attached. This is what a normal pulse would look like coming off of the igniter. I also assumed that there would be 2 pulse sets per revolution.

BUT! When looking through the service manual, it states that there are 250 pulses/100rpm of engine speed. This confuses the hell out of me. First, it doesn't match with cylinder firings at all, and second, how do you end up with 2.5 pulses each rotation.

My tach works using the 2.5/1 ratio, but I'm still quite confused and I'm hoping someone with a bit more knowledge about that signal can explain it to me. Thanks!

 

Hey there

I have just done something similar, i did a post about it last week;

https://honda-tech.com/forums/engine-management-tuning-124/igniter-rpm-output-2846561/

Hope it helps