Gavin Posted December 27, 2005 Share Posted December 27, 2005 I am trying to switch from the standard MS code to MSNS-E on my 280z to control fuel only. I loaded the new code on and selected fuel only mode, and everything looked good except for my tach which read some rediculously high RPM. I am getting my tach signal from the - on the coil. Loaded my old code back and works fine again. Why would this be happening? Thanks. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted December 29, 2005 Share Posted December 29, 2005 which version of the extra code did you try? Be carefule to re-check all settings in the extra code after loading it. Quote Link to comment Share on other sites More sharing options...
Gavin Posted December 29, 2005 Author Share Posted December 29, 2005 I'm trying to use 024s13c with MegaTunix. What settings might be messing me up? Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 1, 2006 Share Posted January 1, 2006 If you have the tach connected directly to the - terminal of the coil, you need a series resistor to drop the voltage going to the tach. I put a 100 Ohm in series with the wire from the - terminal of the coil to the tach. The coil is overdriving the tach. Quote Link to comment Share on other sites More sharing options...
Gavin Posted January 2, 2006 Author Share Posted January 2, 2006 Thanks. It started up with the 100 Ohm resistor, but now reads about 1500 rpm over at idle. Should I use a different resistor? And how would I be sure which? Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 3, 2006 Share Posted January 3, 2006 Thanks. It started up with the 100 Ohm resistor, but now reads about 1500 rpm over at idle. Should I use a different resistor? And how would I be sure which? There is actually a trimpot on the back of the tachometer you can tweak to get it "recalibrated" correctly, but simply adding resistors in series till you get close, THEN using the tweakability trimpot internal to the tach for the final tuning would probably be a better idea... Use several resistors to find the total that gets you close, then see if you can find a single resistor to replace the "package" you assembled. Even if it's only somewhat close, you still have the internal trimpot to make the final adjustments. My Autometer Tach is terribly innacurate below 1100 rpm, but from that point onward, it's dead on. So I live with it, who needs the tach below 1100 anyway? Quote Link to comment Share on other sites More sharing options...
Gavin Posted January 3, 2006 Author Share Posted January 3, 2006 OK cool now I understand how it works. Thanks. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted January 3, 2006 Share Posted January 3, 2006 I didn't realize that you were talking about the tach in dash. Dumb me, I automatically thought you meant the tach in Megatune. oops Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 3, 2006 Share Posted January 3, 2006 I think you may need more resistance. Try a 330 or 470 Ohm. I think that the voltage going to the tach is still a bit high. Quote Link to comment Share on other sites More sharing options...
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