> >         That's the problem, a normal strobe tach does NOT work normally,
> it works
> > OK at some RPMs but not at others.
>
> So what does it do when not working "normally"?  Do you get the
> extra pulse
> half way between the real ones, right after the real one, or what?

        By normally I mean sometimes it reads the right RPM and other times it
either reads to high, to low or even nothing, it's very variable.
        I can't remember, as I understand it the second spark is called a "waste"
spark and is meant to burn whatever is left after the ignition cycle (to
improve emissions and not gunk up the catalytic converter), so I would think
it would occur roughly 1 stroke after primary ignition.

> > BTW I have found what seems to be a tach
> > signal coming from the ignition module, I have to bring my scope to the
> car
> > to see if it's what I want or not.
>
> That would be great if it is really a tach signal.  Maybe you can get hold
> of the shop manuals for your car and see how the optional tach is
> hooked up.
> Most cars have a factory option for a dashboard that includes a tach.  I
> wouldn't be surprised if the ignition module is the same in either case,
> with the tach output not connected when the normal dashboard is installed.
> Maybe you found just that signal.

        Well I just came back and that tach signal is perfect, it's a square wave,
12V peak and runs at twice the frequency of the crankshaft (two pulses per
revolution). Now I just gotta build a simple divider and off I go, thanks
alot to all for the help. TTYL

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