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Discussion Starter #1
I just got my first Z and have begun the restoration project. It starts, but needs work. Everything I've read here pretty much tells me I'd be better off just replacing everything with an electrical connection under the hood. The EFI harness definately needs replacing, since all the rubber breaks if you look at it sideways. I found a harness from a 77 280Z in surprisingly good condition rather cheap but would like to know they are compatable before I spend any money.
 

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???

"The EFI harness definately needs replacing, since all the rubber breaks if you look at it sideways."

Sounds more like the ENDS of the harness needs replacing, most likely the wires contained within are just fine.

At least that's been my experience.
 

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i had the same issue on my 75.... just like tony said. i replaced all pigtails and removed the ends of the harness. but i would check and clean all connections.
 

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It should work fine. I know the 78 is different from the earlier ones but I'm pretty sure those are the same. They are easy enough to remove, you could take yours out, take it with you and compare them side by side. IMHO it's a lot easier to "rebuild" them out of the car anyway and you can then check every connection. It's also well worth buying a new EFI temp sensor but don't waste your money on a new thermo time switch or cold start injector.
 

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Discussion Starter #5
Thanks for your help everyone. I've already tried the cleaning routine. One connector at a time so as not to cross any. It went from poor idle but descent drivability on the highway (really set in at 90 or so) and trouble restarting when hot to descent idle but really bad hesitation when trying to accelerate but no trouble restarting when hot....and the radio won't tun on any longer even though it obviously has power (the red security led still blinks when the faceplate is removed). I seem to just be shifting the trouble around. I'm just going to start replacing it all, rather than nickle and diming it to death trying to resolve one issue after another. It's a lot less frustrating that way.
 

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BEWARE!

The procedure you are contemplating is called "SHOTGUNNING" in the business, and is very dangerous.
You DON'T know what is causing the problem, you THINK it's the harness, but in reality it's the connectors.
So now you are contemplating using another harness assembly with comparable vintage CONNECTORS and similar vintage WIRE, and are betting it will get BETTER.

I bet it won't. It will only do what it's doing now, in a different way.

Proper repair of the harness you have, insuring good connections with NEW connectors (basically a REBUILD of the harness assembly) will solve MORE problems than using another old harness.

You will most likely just move the symptoms around just like you are doing by dicking around cleaning old connectors. Unless you buy a NEW harness, chances are you will just experience the same. If not immediately, within a year.

But rebuilding the harness using NEW terminations (like the nice quick disconnect injector and sensor connectors) will in all practical preformance aspects give you a new harness, at a fraction of the cost.
Added benefits is you can cover the loom the way you want: colored wrapping tape to match your exterior paint color. Tou can ADD WIRES to the harness for things like headlight relays, stereo power, etc etc etc. You can even swap connectors from other brands to allow use of electrical sensors with the SAME resistance values, but with modern weatherpack connectors (like for the TPS, CHT, etc etc etc) Most Nissan sensors from the Z31 series have the same values for resistance for sensing temperature, but have MUCH improved connectors which are not as suceptible to corrosion. This will solve problems in the future by using superior engineering available on later vehicles. May not look stock, but when it works better, I do it.

Just some things to think about. I would REBUILD any harness you buy BEFORE installation. In other words, if you are convinced the 78 harness is in better shape, REPLACE ALL THE CONNECTORS BEFORE YOU INSTALL IT! If you don't there is abot a 95% chance within a year you will be in EXACTLY the same position you are in right now, and will then rebuild the 75 harness you removed. Save yourself the work, and do it right the first time, you will be happier when you do!
 
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