MegaMiata

Hi guys i'm running 1993 mustang ecu. The tach was working fine before I installed a ignition box. It does have a tach out wire. i'm just wondering where is the best place to grab the factory tach wire.

V8MiataMike

The IDM pin 4 at the 60 pin EEC connector is the place to get the tach signal for the Miata tach. That should do the trick.

But I think I used a 22K ohm resistor (from an old Mustang harness I had that is part of that IDM circuitry) and put that between the usual "tach output" wire that comes right off the coil or ignition box to the Miata tach wire.

MegaMiata

Do you cut or splice into pin #4?

Thanks again

V8MiataMike

Splice! Do not cut.

tbone heller

I used an MSD tach adapter on mine.

MegaMiata

What the model number of that msd adapter?

Five-o-joe

I asked Tom the same thing and he gave me MSD part number 8910.

I had the exact same issue and just installed the tach adapter above a few minutes ago. It's literally plug and play....I didn't even have to cut a wire. Tach adapter 8910 plugs into the white and red wires on the MSD ignition box.........that's it...2 wires.

Fired right up and tach works like a charm....

Thanks Tom!

MegaMiata

I just ran the tach out from the ignition box to pin 4 like MiataMike said. It works perfectly . Thanks again

Five-o-joe

No problem....good to know that worked for you.