Making the original cluster Tacho work with Megasquirt

[Turbo_tracker]

first off, thanks for sharing ! nice project, sounds like fun.

I have never reversed engineered the tacho.(i should have..) but It has 3 wires (gnd,12v and sig) and does trigger off the back EMF signal of the stock coil.
im not sure of the stock tacho is sensitive to duty cycle of the pulse. (many are) i suspect it is.

in a good tach its digital and only measures rep, rates but that is not common, in factory cheap tacho's.

what Ignition system are you running, that dictates solution.

cheers !
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Thanks fixkick!!!

Here's schematic that came with the Mega Squirt controller,

http://www.msextra.com/doc/general/ms1external.html

This is almost the way I have it wired, just need to solve some bugs than came out last night..

I didnt installed any custom ignition system: the MS has an option called "Distributor Based Single coil Setup (MSnS)" that gives you the option of using all of your stock components (at least in my case...)

So Im running the stock efi distributor, stock coil, stock tps, stock idle valve at TB, stock fuel pump...
(from that everything is mixed and matched: Evo afr gauge, custom fuel rail with a honda fuel pressure regulator, old junkyard 5.9 liter v8 dodge magnum injectors and some junkyard GM coolant and air temp sensors, etc)

Im using the hall sensor inside the distributor to generate the spark and is controlled by the MS board (it has the option of running a coil with a small internal mod still, I burned some components the first time for not wiring it right hehehe)

The MS board generates the signal for the stock coil to make the spark at the right moment...

Could it be that if I fit again the condenser and the noise filter back again my Tach would come back to life again? like the stock diagram attached?

And to your fist comment: yes it's been tons of fun just to be monkeying around to make solid axle swap, the dual t cases and now to make it perform, had learned a ton of stuff the good and bad way, But I would definetly do it again (now than I almost know how it would take me less time hahaha)

Anyways thanks a lot for the great info and support!!

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Turbo_tracker, just stopping by to complement your project. Love the rims, I was looking at these last night since mine are completely busted. American Racing polished aluminum right?

Thanks and Yep!!!

Found 3 of them at a junkyard and bought the 4th at ebay... And yes the three out of the junkyard took a couple of hours of polishing to match the new one...