Datsun Deron Posted January 31, 2007 Share Posted January 31, 2007 Hey guys, I got my MS-II board all built and tested now im dreaming up how to wire this thing. So far most of it looks pretty straight forward, basicly im going to disconnect the stock 280zx (non turbo) ecu and wire everything with the image below. What has me confused is terminal block 15. Since im non turbo do I need to worry about the dizzy wire. And also can anyone give me some idea of why terminal 15 needs a switched 12 volt. Isn't it already provided on the top right of the Relay Board or are they completely unrelated? I have also read somewhere that the stock 280zx injectors are not polarity specific and that they just need a positive on one side and negative on the other, is this correct? Thanks in advance, Deron, Quote Link to comment Share on other sites More sharing options...
Gavin Posted January 31, 2007 Share Posted January 31, 2007 You will need a tach signal, turbo or not. Do you know if your optical trigger is in your dizzy or off of the crank (Pre or post 82 zx)? I believe the automatic model is different as well. The switched 12v in the diagram goes through whats called a pullup resistor, which you can do a search for to find out more about. If you have a 82+ zx dizzy, follow Moby's diagram in the install guide sticky. I wouldnt bother using any of the stock FI wiring harness, since it is seperate from everything else and can be easily removed. I found this simplifies things because you can be more aware of whats going on. And yes, fuel injectors do not have a polarity. At least none that I have heard of. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted February 1, 2007 Share Posted February 1, 2007 the fast and dirty way out would be to leave the ign system alone and pick up tach signal from - side of the coil.since its a na car the stock efi does not connect to the ign system except for tach signal.i would ditch the old efi harness and get some injector connectors and sensor connectors and build a all new harness.you will spend more time in the end troubleshooting old junky nissan efi stuff.step into the 21st century-you can build your car as good as any new car with the correct parts. Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted February 2, 2007 Author Share Posted February 2, 2007 My car is an 81 280zx, so the wiring scheme is a little different. I do like your idea though Randy 77zt, I think connecting it directly to the coil is by far the simplest idea and that just might be the way to go. So just to confirm would I still need the resistor and go direct to the negative on the coil like the picture illustrated below. Or is there a resistor already built into the wire that isn't showing in the Manual? The book actually mentions that connection "L" on the dizzy that goes to the Negative on the coil should have 11.5 to 12.5 volts. Here's the wiring harness picture as well for my Non-turbo dizzy. If i was going to attempt to follow turbo dizzy picture from Moby's sticky, based on the information on the following troubleshooting page it mentions "Br" to be tested in "start" ignition key position and "L" to be tested in the "on" ignition key positon. So I'm thinking "L" would have to go directly to 15 on the relay board, with a switched 12volt and a pullup resistor on the same wire. (keep in mind L goes to the negative side of the coil). "Br" would be my 12v, but I'm unsure if it would really have to tie into the circuit the way it does currently. Then "LY" and "LW" would be discarded. These appear to be used for the mechical advance which has been removed previously. I then would have my ground grounded of course (which isn't shown). Anyone know if this would work? I suppose the big interest in the 2nd method of the tach signal is to have megasquirt wired so it doesn't rely on the original mess of wiring. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted February 2, 2007 Share Posted February 2, 2007 The non-turbo distributor is a completely different animal from the turbo unit. If you are using Randy's method and leaving the distributor in control of the spark, you would wire the relay board's Tach terminal (pin 15) to the negative terminal of the coil / L wire, with no resisotrs, pull-ups, or anything. If you've removed your advance mechanism altogether and want Megasquirt to control the timing, you would wire this up differently. I can post one possible solition if you are interested in that. But you would have to lock the advance inside the distributor and disconnect the vacuum advance to do this. Quote Link to comment Share on other sites More sharing options...
naviathan Posted February 2, 2007 Share Posted February 2, 2007 Ok if nothing else I'm interested in this. Please post. Quote Link to comment Share on other sites More sharing options...
Datsun Deron Posted February 2, 2007 Author Share Posted February 2, 2007 Yea, im not doing spark control yet at this point. Im hoping just to get it running on fuel only to begin with and then move to a spark setup. However I'd be very intested in seeing how I could control the timing using MS if it's not too much of a bother. My vaccum advance has been removed, and the advance has been locked inside the distributor as well. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted February 5, 2007 Share Posted February 5, 2007 Ok if nothing else I'm interested in this. Please post. Ok, for a locked advance, here's something that should work. 1. Build the Megasquirt the same way as described in our regular article. 2. Disable all advance mechanisms in the distributor. 3. Run the L wire to pin 24 (Tach if you're on a relay board) with a pull-up resistor from a 12 volt source (the BW or BR wire should work). Disconnect the L, but not the BW wire, from the coil. 4. Remove the LY and LW wires from the distributor. 5. Connect the pin 36 (relay board S5) wire to the negative terminal of the coil. While I haven't tested this one, it ought to work. Quote Link to comment Share on other sites More sharing options...
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