what is it like pulse per min?

and what the difference between. 4,6,8 cyl?

this is sord of a dumb question but i cant find it anywhere

 

it's a 12v square wave signal.

 

Yeah, the if you view the ignitor triggering the primary coil on a scope with the on/off, on/off that is what basically creates your tach signal. That's why the tach jumping around is an immediate indicator of an ignitor problem.

 

the only difference between 4,6,8 is the way the tachometer is calibrated to convert the number of reference pulses into engine speed using rpm display on the tachometer. It takes 2 crankshaft revolutions to fire all the cylinders once. On a 4 cylinder, that would mean 4 pulses is 2 rpm. At idle speed if the tach is recieving 1600 ref pulses pm it converts it to 800rpm. Now On a 6 cylinder 1600 ref pulses pm would mean about 530RPM.... you get the point.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Flexmyrex &raquo;</TD></TR><TR><TD CLASS="quote">the only difference between 4,6,8 is the way the tachometer is calibrated to convert the number of reference pulses into engine speed using rpm display on the tachometer. It takes 2 crankshaft revolutions to fire all the cylinders once. On a 4 cylinder, that would mean 4 pulses is 2 rpm. At idle speed if the tach is recieving 1600 ref pulses pm it converts it to 800rpm. Now On a 6 cylinder 1600 ref pulses pm would mean about 530RPM.... you get the point.
</TD></TR></TABLE>

thats what i was looking for, thanks alot!!!