Where does the tachometer get its signal from?
 

I am trying to make some RPM activated switches, but I need to know where to get my signal from.

Some info on what the signal will look like would be helpful as well.

Thanks,
Jason

leading coil, I 'll go look for you on my car if you want, but you should look in the fsm.

Actually it taps off the trailing coil pack...
Either trailings or leadings have a female bullet connector which you can tap for a tach signal.


-Ted

Ted is right, all electronics (like cruise, gauges, power steering, etc) requiring a tach signal in the FC get the tach signal from the trailing coil pack

My tach starting not working properly, so I took it down to the mechanic, he said that it was the leading coil. there are actually two leading coils and an ignitor. each leading coil is $125, and the ignitor is $500 OEM. you can also buy it in a package... not sure on the cost.

That was fast:)

Do any of you know what the signal looks like?

Thanks guys.

Standard tach signal, which is a "pull down" square wave.&nbsp Sorry, I can't give you duty cycle or pulsewidth times... :(

-Ted

Duty cycle is no big deal.

So it is just a simple square wave?

Yes, like most tach signals, it's a "negative" square wave...


-Ted

stock7....ditch your mechanic. He's taking you for a buggy ride. See http://www.teamfc3s.org/info/articles/demystifying.html and or the schematic https://www.rx7club.com/forum/attach...postid=1398836

Cool.

Howmany Pulses per revolution? 3? 6?

I believe the trailing pulses are 3 per full revolution.

Yep, fire that mechanic, he's very wrong. The tach is driven by the trailing coil as mentioned; plus the leading coil is one double-ended coil with one ignitor. It's the trailing coil that's actually two seperate coils with two ignitors.

Revolution of the e-shaft?&nbsp One.
Revolution of the rotor?&nbsp 1/3rd. :)

It fires like a 4-cylinder, I believe, so it's one pulse per 1 RPM.



-Ted

Are you sure?

How many times does any one spark plug fire per revolution of the e-shaft?

Once right?

A single rotor fires once per revolution. So a 2-rotor fires twice per revolution, same as a 4-cyl.