tunerstudio showing half the real rpm!!

[feak1]

hi there
i just started my bike today and i noticed that my tach in tunerstudio is showing half of the real rpm? ( using microsquirtV3 with code 3.830).
My bike is a 4 cylinders with 2 coil pack working as wasted sparks
i use the negative side of just only one coil to give me rpm (since its wasted spark it will spark every crankshaft turn giving me the right rpm)

the way i get rpm is :

opto+ (gray/red) to a 12v source when i turn the key "on"
opto- (gray/black) with a 1k resistor and diode banded toward the negative coil

i ve search a lot on " triggering from a negative coil " and a lot of people uses the opto+ with 1k resistor and diode banded toward negative coil and opto- to a 12v source....but that gives me 0 rpm.... i tried various combination and the only one that seems to work is the one with the opto- in the negative coil and opto+ on a 12v, the complete oposite of what the manual says !!!

is this why i get half the rpm readings in tunerstudio?
am i gonna burn the opto circuit plugged that way?
could it be that opto+(gray/red) is in fact gray/black and opto-(gray/black) is in fact gray/red?

[Matt Cramer]

If triggering off one coil, set the MSQ for two cylinders.