Swervey McZCar Posted March 27, 2009 Share Posted March 27, 2009 I have a mostly stock L28ET in a 79zx with a stock ECU. N42 intake, Pallnet fuel rail, 60mm TB but nothing really special or fast. I ordered some "low profile" EV1 connectors from connectorsfast.com. I like them, but the pigtails they crimped on for me are a little strange. I thought the wires were of two different gauges but after further inspection I believe now only the insulation is different (one wire just looks thicker than the other). Anyway, I know all things being equal it does not matter which wire connects to pos or neg, but in this case, what would you folks do? The negative gets switched, right? Is that where I want to reduce my EMI? Does it matter? Probably, that is why I ask Thanks, -Stan Quote Link to comment Share on other sites More sharing options...
Challenger Posted March 27, 2009 Share Posted March 27, 2009 Not completely sure what your question is but Ill let you know what I did. What do you mean the negative gets switched? Im pretty sure it matters the wires being connected in their original places. Just look at the orientation of the original plugs. On my car the green wire is on the left side of the connector when the side with the round cutout is facing down.. From there you just place the new connector in the same orientation and wire it up. Quote Link to comment Share on other sites More sharing options...
Chemicalblue Posted March 27, 2009 Share Posted March 27, 2009 I would just make sure the pigtails are wired the same as the originals. I don't think under normal circumstances EMI's would ever come into play. However, you could rap everything in foil to make it UFO proof, I hear they really put out a lot of EMI's. JK:burnout: Quote Link to comment Share on other sites More sharing options...
Swervey McZCar Posted March 27, 2009 Author Share Posted March 27, 2009 However, JUST to be clear, what he was saying is that most fuel injected vehicles provide a constant feed of positive voltage to the injectors, and let the ECU switch them by switching ground. In other words, you should have a constant 12V+ to one side of the injector, and nothing to the other side. You should be able to check for continuity between the other side, and ground, and get nothing.. UNLESS you are cranking the engine, and then you should see an intermittent ground on the other one. Now, I read the L-Jetronic Bible about two years ago.. I havent had my Z running since shorlty BEFORE that, so I havent worked on Z FI since then.. BUT I am pretty sure he was exaxtly right, and the ECU switches ground to the injectors to activate them. IIRC, the constant positive comes from the dropping resistor, but don't quote me on that... So, if you have the negative lead on a good chassis ground, and the positive lead on each injector wire, and crank the car, one wire on each inj. should run +12VDC, steadily. the other wire should register nothing, or MAYBE show an intermittent -12VDC. More likely, the other wire would register nothing, and then you leave the leads connected as they were to the other wire, and switch your multimeter to continuity.. then, while cranking, you should see fluctuations between continuity and non.. IE, no resistance, then infinite resistance. This is where I got some of the notions I was/am working with. It has been a little while. I THOUGHT I had read that the polarity of the injectors did not matter. If that is wrong, I'll need to figure out which side of the injector connector need pos. as I cut off the butt connected crap the PO installed (not you Simon, the guy who sold me the turbo donor). Quote Link to comment Share on other sites More sharing options...
Warren Posted March 27, 2009 Share Posted March 27, 2009 For the 8 billionth time, polarity doesn't matter on injector connectors, however, you're right, the ground is switched on and off by the ECU. Insulation size differences on these connectors doesn't really matter either. I'd be more concerned about whether or not the connectors are sealed at the top (meaning having rubber boots on the wire part) and make sure to use dielectric grease when you install them to keep moisture out of the connections, thus preventing the copper/brass/whatever contacts from corroding so horridly as they will eventually if they're left unprotected. Quote Link to comment Share on other sites More sharing options...
slown280z Posted March 27, 2009 Share Posted March 27, 2009 It doesn't matter, but it makes for nicer wiring if you follow a specific way of wiring them. Stock is +12v side nearest the radiator (I think...). Quote Link to comment Share on other sites More sharing options...
Swervey McZCar Posted March 27, 2009 Author Share Posted March 27, 2009 I appreciate the help and advice! Quote Link to comment Share on other sites More sharing options...
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