How do I hook the stock tach to my EDIS?

[aaron7]

My car is an 89 MR2, 20v silvertop, megasquirt, and Ford EDIS. I want to hook the stock tach up, but I guess the coil packs output a 2 cylinder signal? Least that is what I was told.

Anyone do this before?

[brink]

Moved to tech for techies exposure.

[fredk]

your going to have to come off the tfi module somehow, do you need a diagram of the escort the system came from?

[aaron7]

I have no idea!

[fredk]

ok, about what year and motor did it come from?

[aaron7]

Mid 90's Ford Escort 4 cyl is all I was told.

[fredk]

i added you to my aim list

[toyotaspeed90]

there's 2 easy ways.....

1) i don't have the diagram... but it involves 2 or 3 diodes and a couple zener diodes.... look it up on google or the MSEFI reference pages... you'll find it after some digging

2) MSD MAKES a unit that is prebuilt to do this. It's around $100 depending on where you buy it

i'm pretty sure that nobody has been able to use any of the wiring directly from the edis unit to drive the tach

me personally.... i just have learned to drive the car w/o the tach

[zoni]

isnt there anything in the MS programming where you can change this?

[aaron7]

Well I tried hooking the stock tach wire to the second pin and the second to last pin on the igniter assembly... no go. Someone suggested this.

I have also heard of this diode setup. I believe it was 2 diodes and one zener diode... but I have no idea what values or where it goes!