MS II and tach hook up ?

[Clifton]

What tach are you guys using in the S30's. My tach has the Supra guts in it to work with the stock 7M ECU and it's not that accurate so I'm better off getting another S30 tach if they work with MS.

[z-ya]

If you are going to run the MS with a single coil, then just a 280Z tach will work. Run the - terminal of the coilf through a 470 Ohm resistor to the tach. If you are doing EDIS, you can essentially wire "OR" the - terminals of the coils, again using resistors. The MS documentation shows you how.

[Clifton]

I'm going to run the EDIS ign mod into the Toy coil packs. Would it still be a 470 ohm resistor with EDIS? What do you mean by terminal of 2 of the coils? I will have to search somemore. There is so much info out there. It took a few hours searching to find how to run a 3 or 4 bar map.

[z-ya]

OK, now I can't find that page in the online EDIS documentation. I did print it out, and I have it at home. I'm in Taiwan now, so when I get home I'll take a closer look. I'm also doing an EDIS project, so I'll let you know how the tach hookup works.

 

What you need to do is run a wire from the - terminal of each coil to a 470 Ohm reisistor. Then take the unconnected end of all three resistors, and tie them together. Connect a wire to this node, and run this to your tach. Basically the wire OR make a simple logical OR of all three coils. So if any of the coils fire, the tach will get a pulse.

 

BTW, a 280Z tach fits nicely in a 240Z housing.

[Clifton]

Thanks for the help. After your last post I went back to there site and have been there since then reading. I found the page you were talking about. http://www.megasquirt.info/ms2/EDIS.htm Very bottom of the page.

[z-ya]

Yes, that is the one. Thought it was a wire OR using resistors, but now that I think of it, that wouldn't work. You need to use the circuit in the link you posted. This uses diodes to provide an OR of the coil inputs, and isolation.

 

 

The above schematic is for a 4 cylinder wasted spark setup. You will need another diode for a 6 cylinder wasted spark arrangment.

[cygnusx1]

I wanted to ask about the tach hookup to my 76Z tach with MS-II using the 83 turbo system. I think I figured it out.

 

The 76Z tach originally was wired directly from the negative coil post, through the factory inline resistor under the glove box, and to the tach. I figure nothing should change with MS-II. Just run the wiring exactly how the factory had it. (-coil)---->resistor---->tach. It should work fine.