Swapping my 75 280z engine to a 81 L28det need help

[jesus]

I am swapping my engine out for a 81 turbo model on my 75 280z what I was wondering is what harnesses I need in order to get my car running I have all the harnesses from the 81 l28det from inside to outside would I have to swap all the harnesses but be able to run the 75 280z gage harness ? 

[cgsheen1]

You really just need the engine harness itself.  I usually keep the EFI Relay and Fuel Pump Relay intact (simpler than the 280Z circuitry) and sometimes use the 280ZX fusable links (that have to do with the ECCS and injector power).  There is a small harness on the 280ZX that comes from under the dash, up the driver fender, to the coil and ignitor that I find useful but it's not completely necessary.  There are several other wires in that harness that have nothing to do with the coil/ignitor so I strip them out if I use it.  (No point really - most of the wiring you need for the turbo coil/ignitor - and your Tach - is already there on the stock 280Z.  You just need to add one wire from the ECU to the Ignitor to make the whole thing work.) 

If you're going to use the stock harness: Get yourself some DeOxIt (made by Caig) and AFTER you clean each electrical connector on the harness, engine, ECU, AFM, sensors, (well, you get the idea - EVERYTHING!) use DeOxIt on the connections before you put them together!  There are specialty tools made to clean the oxide and corrosion off the brass connectors.  I would say that over 90% of the problems people generally have with these early EFI / ECCS engines are electrical - most having to do with wiring and connectors.  These old harnesses were never weatherproofed (and never meant to last this long).  EFI/ECCS is dependant on reliable signals from sensors to function properly.  Oxidation of the wire and connectors creates increased resistance which skews the signal from the sensors.  Eliminate as much of that as you can. 

In reality, most of us have had to abandon the stock harness.  After months of troubleshooting, my stock harness worked pretty well and I drove my turbo-swapped 260Z for years with it.  When I went to a different ECU and built a new harness, I came to the conclusion that I should have done that in the first place.  Live and learn as they say...  

[jesus]

sound easy enough so you say you got a new harness and ecu what did you go with and anything helps thank you a lot i was having a big head ache because i was thinking that you needed all the relays and all that but it seams easier then that 

[cgsheen1]

Oh, I'm sorry.  I made it sound easy?  I guess that comes with over-simplification.  You'll find out.

[JSM]

I would still run the 81 stuff for the time being.  You will learn a lot.  Then upgrade later.

[jesus]

So if I run everything from the 81 on 75 how would I run my gages and stuff 

[cgsheen1]

You're swapping in a slightly newer version of the engine that that was already in the car. You'll be able to reconnect or reuse everything that has to do with your gauges.

[jesus]

do you mean put in the wiring harness from the 81 into my 75 and connect all the the plugs running to my gauges ? if so the plugs dont fit 

[Zed Head]

He means that your gauges are on a separate wiring harness than the engine control system harness.  That's the key to what you're talking about doing - the harness for the engine and its computer is separate from the body harness that controls your gauges.  You might have to swap oil pressure senders or bring over more 1981 parts than just engine control.  There's also fuel pump control to worry about.  It's not plug and play, it's complicated.

Get the wiring diagram from the Factory Service Manual and study it.  It shows all of the connectors. 

[jesus]

yea thats what i was worried about sense theres a whole other harness full of relays and stuff 

 

[jesus]

Ok so I get that I have to just put in the engine harness but what do I do with the old harness that hose into my passenger side that hooks up to my gauge I’m so confused on that if I want to run my old gauges what do I do 

[heyitsrama]

You'll have to tap in the old harness into the hardware that talks to the gauge. So things things like the voltmeter/tach/speedo (gearbox driven)/Fuel/oilpressure should remain unchanged. For the stuff that talks to the ECU, if the wiring allows you, you can jump in the corresponding connectors for the AFM / injectors / etc. 

 

Edit*  you might find what you're looking for by searching over on hybridz.org, they have loads of people that like to do these swaps, and might have good insight to the issue. 

here's links to get you started:

http://forums.hybridz.org/topic/113801-81-l28et-swap-into-73-240z-wiring-help/

http://forums.hybridz.org/topic/122072-l28et-swap-wiring-confusion/

http://forums.hybridz.org/topic/67309-l28et-swap-wiring-answer/

Edited May 22, 2018 by heyitsrama