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Z31/300zx ECU/MAF to 280ZXT swap guide

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Phil I had a quick question. So you changed all the pins over and only spliced what was necessary for this swap right? Mainly I'm just curious because you mentioned having the similar problem I seem to where every so often the car starts acting up and it seems to be the plugs/harness. I see you said you've put about 800 miles on the swap, is that generally farther than you've managed to go compared to the 280ZX plugs where you'd have to re-seat them every so often? Recently my 280Z with turbo swap has been acting up, it has the Z31 ECU swap done to it and I was shaking the harness and found it to stumble every time I'd mess with the ECU/Harness so that prompted me to change the plugs. I can see that when just removing the pins from the 280ZXT ECU connectors that the pins had quite a bit of play in each connector. I could really move them back and forth quite a bit in the connector, where as like you mentioned with the Z31 plugs how they have those extra inserts to help keep them pushed forward and in place, along with smaller tunnels to center the pin better.

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Duo, my ECU connector issue was intermittent. I could go several hundred miles with no issues. Then one day it would start and progressively get worse. It happened one time several years ago on an extended trip. First the feeling that a large hand was holding the car back when trying to accelerate. Over the course of the next few hours it had degraded to the point where I had trouble maintaining highway speed while going up hill. I eventually pulled over, reseated the plugs a few times and the car ran like new for the rest of the trip.

 

I have to say that since the swap I have not felt the car held back at all. If anything it is much more responsive then before. Only time will tell whether these connectors have completely eliminated this issue.

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Can anyone tell me why in my 280zx harness pin 20 is empty? It should be complete harness, but when I checked I'm missing pin 20. I know it's not needed in this swap, but I just wanted to check the pin, because it was mentioned in the beginning of the topic.

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I just completed this conversion minus the 02 sensor. I have an 87 turbo ecu on the ET. It will idle at about 1000 and misfires. It super rough and barely revs up, missing as it barely even gets to 3000.

I suspect its the maf itself. The Maf is getting correct grounds and + voltage. I have the correct ecu pins to the + and - of the coil. I disconnected the dropping resistors and twisted the remaining wires together.

My wide band is reading lean in the 16-17s and it will randomly go rich to the 13s and back to lean

 

Its pulling 20 in/hg at idle

 

I should also note, in the distributor I used the l28 rotor as opposed to the z31. I figured it just distributes spark so it wouldnt matter.  Could this be causing an issue?


The last car this ecu/maf/optical sensor was on was apparently running fine.

Any tests or input anyone has in mind would be greatly appreciated. thanks!

Daniel

 
 
Edited by SDgoods

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Sounds like he had a MAF wiring issue, MAF issue, or bad CHTS.

 

Some pics from the swap on ours.

 

1461068_10200879988509503_470631268_n.jp

 

1453495_10200884948553501_2084729505_n.j

 

I need to clean up wiring from the PO's GM ignition module swap next.

 

1471829_10200885167398972_1244048877_n.j

 

1468720_10200890672056585_1779733375_n.j

 

1451526_10200743057326309_343628934_n.jp

 

With my experience in wiring up engine swaps and other stuff, it took less than 4 hours to complete. I found myself relying more on FSM wiring diagrams than the writeup though. Some of the wire colors in the writeup (almost all) didn't match our car for some reason. I also ended up just swapping all 3 of the ECU pigtails because I prefer the Z31 style connectors - they're a much better design that holds the pin better. haha

Edited by michaelp

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Hopefully this gets answered, I have my fuel pump isolated and has its own individual 12v switch, no relay or anything, with my 280zxt harness in my S30 I was having too many issues, so I wired it up independently from the ECU harness. With it that way will I have to worry about wiring it back up to the Z31 ecu or harness to have it run properly or can I leave it be?

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You'll lose the safety features and the voltage/pump speed control.  Noisier than necessary, more load on the electrical system at idle.  But the Z31 ECCS can't control the pump without its associated relays, so if you don't have those you shouldn't be trying to use ECCS control anyway.

 

The picture's from 1986.  1984 is similar.  Around page 27-29 in the EFEC chapters.

post-8864-0-29640400-1407688815_thumb.png

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You'll lose the safety features and the voltage/pump speed control.  Noisier than necessary, more load on the electrical system at idle.  But the Z31 ECCS can't control the pump without its associated relays, so if you don't have those you shouldn't be trying to use ECCS control anyway.

 

The picture's from 1986.  1984 is similar.  Around page 27-29 in the EFEC chapters.

That sounds like a lot of relays. Eventually, (or initially) I will be using a "cleaned up" Z31 harness in place of the 280zxt harness, and when I approach that I will attempt to rewire the fuel pump and FPR to run as it should in that diagram. But in the meantime I just want it to run (reliably) before I change my fuel pump configuration.

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I believe another safety feature of the ECCS controlled fuel pump is that power to the pump is shut off if the engine shuts down.  Important in the case of an accident where you don't want the pump to continue running and possibly dumping fuel into the damaged engine bay.

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Bumping this ol bugger.......can someone clarify which terminal slot 3 wire connects to on the coil?

 

3) Insert new pin into slot 3 of ECU connector then connect to a new wire going to the _______ terminal of your coil. The car seems to run OK without this step, but I still wired it since it was done on the 300zx. I have a MSD and the car is doing well with it

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