letitsnow Posted June 14, 2012 Share Posted June 14, 2012 How are you EDIS/COP/waste spark guys driving the coil? I see the circuit in the manual that calls for a relay coil to generate the high voltage pulse, but that seems like it would make an annoying chattering noise. Anyone come up with something better? Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted June 14, 2012 Share Posted June 14, 2012 The tach output from Megasquirt? Quote Link to comment Share on other sites More sharing options...
letitsnow Posted June 14, 2012 Author Share Posted June 14, 2012 It needs a circuit built to drive the tach, the tach looks for a high voltage pulse(20ish v) from the (-) side of the coil, that's what I'm wondering about. Quote Link to comment Share on other sites More sharing options...
Xander Posted June 14, 2012 Share Posted June 14, 2012 If you have a early style, current trigger, tacho then it is quite easy. I am running the IGN-6 coilpack from DIYautotune. The positive lead goes from the fusebox to the loop on the backof the tacho and then to the coilpack. It works just like OEM. hope this helps. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted June 15, 2012 Author Share Posted June 15, 2012 I should have stated that I have a later, 280z tach that was triggered off the negative side of the coil. Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted July 9, 2012 Share Posted July 9, 2012 Did you find a solution letitsnow? My dash tach is the only incomplete part of my install, and the local electronics scene is sparse. I found a short blurb on another site about using a GM 4-pin HEI module that looks promising and cheap to try. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted July 9, 2012 Share Posted July 9, 2012 You can create a diode bridge to do this. http://www.msextra.c...re.htm#tachoout That's how I drive the 280Z tach with EDIS. I don't see why you couldn't use the same approach for COP with 6 diodes instead of 3. Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted July 10, 2012 Share Posted July 10, 2012 I saw that, but I'd rather try to use the tachout pin that I have currently unused, if for no other reason than to avoid splicing into a working ignition harness. Thanks for the suggestion though... Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 11, 2012 Author Share Posted July 11, 2012 I haven't really put much effort into a solution, I think MSD offers a 'tach adapter' which is kind of what we're looking for. Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted August 21, 2012 Share Posted August 21, 2012 The MSD 8920 Tach Adapt does indeed work. The good news is that my tach is virtually identical to what TunerStudio is reporting. The bad is that is shounds like a meth-dosed cricket. So after a week of trying to live with it, it had to go out under the hood. Quote Link to comment Share on other sites More sharing options...
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