HeatRaveR Posted February 10, 2008 Share Posted February 10, 2008 I'm trying to utilize as much of the existing wiring on my '82 280ZX Turbo as possible while installing my Megasquirt. That said, the stock wiring for the injectors appears to have the positive leads connected directly to a fusible link connected to the battery, meaning they're "always hot". However, on most Megasquirt wiring diagrams I see around here, it looks like people wired their injector positive leads to a relay. I'm wondering if that's really necessary, or if it's fine if I leave it as the factory had it, and just connect their respective grounds to the Megasquirt? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 10, 2008 Share Posted February 10, 2008 I think you'll find that injectors are negative-switched. Ie, the positive lines are always fed, and the ECU switches the negative side. Dunno if that helps. Dave Quote Link to comment Share on other sites More sharing options...
Guest TeamNissan Posted February 10, 2008 Share Posted February 10, 2008 Ya, I agree with helix that in my experience thats always been the way. Hard wiring the injectors would be a bad idea. Quote Link to comment Share on other sites More sharing options...
stprasinz Posted February 10, 2008 Share Posted February 10, 2008 The only thing that the relay would do is act as an interuptor to cut the + feed when the key is off. He isn't saying to hard wire them. He is saying not to rewire them in the first place. If you are comfortable leaving the 25+ year old wiring intact then I guess you probably could. And since you said you want to use as much of the original wiring , I guess it couldn't hurt.... Good luck. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted February 11, 2008 Share Posted February 11, 2008 I would definitely replace it. I would also NOT leave 12V battery power hooked up to the injectors. Rewire it with fresh wire, relay it and fuse it. 12V Ignition is supposed to be hooked up to the injectors, but it should have fresh wire, fuse and relay. The factory fusible links are a fuse of sorts but they are very questionable condition anymore. My 12v power wiring had rubbed through to the chassis and also rubbed through to the ground wiring. It was seeping LOTS of current straight to ground and ready to start an electrical fire. I would recommend doing the fusible link rewire at the minimum. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 19, 2008 Share Posted February 19, 2008 Rewiring the stock harness to work with the Megasquirt's EFI controlled relay to switch power on to the injectors is a REAL EASY hack on the stock harness. All the power wires to the injectors come in a big cable which is spliced to go to the individual injectors. On N/A cars, the resistor pack is the easiest place to make the switch as it comes from the battery in one cable, which you hook to your relay, and viola...done. Same for segregating and grouping the grounds for the MS to gate them. Spend some time with the factory wiring diagram, and it will become self-evident. Quote Link to comment Share on other sites More sharing options...
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