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

[Swervey McZCar]

Nistune is cool. That was the whole reason for me to perform this swap. Don't use a "Parts Store MAF on this swap BTW. It does fine at stock levels of boost but runs out of capacity at 10psi or so. I finally found a good working MAF in the yard (first 2 were DOA) and I'm having fun with Nistune. Talk to Andy at Autovaughn performance.

[ArchetypeDatsun]

My Car has been having problems running well, it's doesn't feel like it should basicly when I start running in first gear the car has no power at taking off. I've used like 4 different maf's but I ended up using My adjustable maf because they pretty much did the samething. To be honest I have no idea if the chopper wheel was even installed since I got the motor from a donor car that had the Z31 ecu maf swap so I didn't bother to change it to stock. And I did notice there was a wire running to the fuel pump on the donor car is that another reason for my car running like crap?

 

Could anyone supply good pictures of the accuall procedure that would help a lot I know it's kinda dumb for me to ask I just don't know where everything is at and what I need to remove or add.

Edited June 2, 2010 by 280zx@541

[PapaSmurf]

I just purchased a z31 n/a ecu to install into my 78. I've been running carbs for years so I have no harness and no ecu in there right now. The engine is out of an 81 n/a with p79 head and it has the 81 electronic distributor. I need a shopping list though, I have the intake manifold from the 81 with all wiring and injectors and plumbing. I need a wiring harness which one, I need a chop wheel? What else? I also have the maf coming too. so with no harness what should I get z31 or zx to match the manifold?

 

edit: finally found someone who did a na to na swap looks like I need the 82-83 zxt dizzy, the z31 wheel, the turbo oil pump shaft and the z31 harness am I missing anything?

Edited June 16, 2010 by PapaSmurf

[ArchetypeDatsun]

HEY GUYS I UNPLUGGED MY CHTS AND ALL OF A SUDDEN MY CAR RAN WAY BETTER, THE ONLY ISSUE NOW IS THAT AT TIMES IT FEELS LIKE IT LOOSES POWER. WHEN I RUN IT TO ABOUT 4K RPM AT EVERY GEAR IT WILL FEEL KINDA ROUGH, AND THATS WHEN ITS WARMED UP BUT THEN ALL OF A SUDDEN IT WILL GO AWAY AND WILL RUN GOOD AGAIN. I HAD THIS PROBLEM BEFORE BUT IT WAS WORSE, WHEN THE ENGINE WAS COLD IT RAN HOW IT SHOULD NICE AND STRONG BUT WHEN WARMED UP THE CAR RAN LIKE CRAP LIKE SUFFICATED AND AGAIN AT 4K RPM IT FELT ROUGH LIKE IF IT WAS ON THE REDLINE?

 

ANY IDEA ON WHAT IT COULD BE? I HAVE THE RIGHT O2 SENSOR WITH THE 3 WIRES BUT ITS NOT COPPER WELDED IN, ITS KINDA LOOSE ON THE FLANGE. DON'T KNOW IF I NEED THE CHTS FROM A Z31

 

HELP IS GREATLY APPRECIATED!

 

P.S. MY ECU IS A 87 Z31 TURBO ECU & MAF.

Edited July 2, 2010 by 280zx@541

[PapaSmurf]

HEY GUYS I UNPLUGGED MY CHTS AND ALL OF A SUDDEN MY CAR RAN WAY BETTER, THE ONLY ISSUE NOW IS THAT AT TIMES IT FEELS LIKE IT LOOSES POWER. WHEN I RUN IT TO ABOUT 4K RPM AT EVERY GEAR IT WILL FEEL KINDA ROUGH, AND THATS WHEN ITS WARMED UP BUT THEN ALL OF A SUDDEN IT WILL GO AWAY AND WILL RUN GOOD AGAIN. I HAD THIS PROBLEM BEFORE BUT IT WAS WORSE, WHEN THE ENGINE WAS COLD IT RAN HOW IT SHOULD NICE AND STRONG BUT WHEN WARMED UP THE CAR RAN LIKE CRAP LIKE SUFFICATED AND AGAIN AT 4K RPM IT FELT ROUGH LIKE IF IT WAS ON THE REDLINE?

 

ANY IDEA ON WHAT IT COULD BE? I HAVE THE RIGHT O2 SENSOR WITH THE 3 WIRES BUT ITS NOT COPPER WELDED IN, ITS KINDA LOOSE ON THE FLANGE. DON'T KNOW IF I NEED THE CHTS FROM A Z31

 

HELP IS GREATLY APPRECIATED!

 

P.S. MY ECU IS A 87 Z31 TURBO ECU & MAF.

 

You need the cas sensor from the z31. Make sure it is not upside down. I've been trying to get a hold of parts for this swap for months now. I have everything but the oil pump to dizzy shaft (I bought one but it turned out to be from an 81 turbo eg not star pattern) and the wiring harness. If anyone has the wiring harness or shaft let me know.

 

I'm starting to rethink this as an intermediate step before megasquirt. I may just sell the parts I've collected and jump to megasquirt. Since I have to figure out everything from scratch anyways

Edited July 25, 2010 by PapaSmurf

[Daphur280]

So I have an 83 L28et in my 240z, I've bypassed the Fuel Pump Relay Harness connection on the EFI harness and made an independant relay harness that is switched from the ignition switch. With that would I have to worry about making changes to the ECU harness if I'm staying with the 280zx Harness instead of going to the 300zx harness? Also I have an 89 300zx Turbo Auto Trans ECU. I've read through the thread however not sure if there will be any differences in wiring up the MAF. So far I THINK the only difference in wiring I saw at all is the O2 Sensor, which I'm not sure how I will wire up if it is a 3-4pin connector.

 

Anyway if someone can provide some insight or deirection it would be greatly appreciated. My car simply will not run well with the AFM, regardless of what adjustment I make, so I'm "forced" to do this modification. It takes me 5 min to get up to freeway speeds in my Z and it sucks...

[Scott_M67]

Has anyone figured out the proper way to wire in the later model 02 sensor for use with the 87-89 boards. Do you just use pin 24 for the 02 signal and then ground one wire and provide power to the other wire?

 

Thanks

Edited October 19, 2010 by Scott_M67

[Kali]

Adapting a 1984 300zx turbo/Z31 MAF and ECU to a 1983 280ZXT harness:

 

Disclaimer: First, electrical shorts can burn out your EFI and/or cause a car fire. I have no interest in anyone doing this and don’t know if it will work for you or not. I have no formal training and am only sharing what I did for myself. There is no guarantee nor should any inference whatsoever be made that anything posted below is correct or safe.

 

Purchased parts: 1984 Z31 turbo ECU, MAF, any 84-89 300zx crank angle sensor/chopper wheel (the wheel has a top and bottom, do not reverse or car won’t idle properly) and MAF and ECU connectors with several inches of wire attached.

Also need wiring diagrams of both cars.

 

Nomenclature:

Mass air flow sensor = MAF

Air flow meter = AFM

Fuel pump relay = FPR

z = from 280ZXT

zx = from Z31 / 300 ZX

Example: zx 30 y/b = # 30 wire/pin which is colored y/b (yellow with black line) on the 300 ZX system

Also, I crimped every cut wire to connectors so I could plug and unplug all the changes.

 

CONNECTING THE MAF:

Cut the wires to the AFM a few inches back from the clip

Take clip and wire from MAF then:

1) Connect MAF Position A/wire 30 y/g to 30 y/b wire from z harness

2) Connect MAF Position B/wire 31 b to 31 y/r wire from z harness

3) Connect MAF Position C/wire black to body ground

4) Connect MAF Position D/wire 26 b to 26 b wire from z harness

5) Connect MAF Position E/wire 27/35 b/w to any ignition activated + powered wire (pin 27 and 35 are + ignition wires on the same circuit, they are b/w (black with white strip) and can be tapped into from either b/w wire going to the 2 V.C.M solenoids that are located under the AFM bracket

6) Connect MAF Position F/wire 12 r/w (for cleaning cycle) to 33 y/l wire from z harness

 

CONNECTING THE Z31 ECU to the Z HARNESS:

There are a few of the ECU connector pins that are different. I got an ECU connector clip from the junkyard and then cut it open and took out three metal pins with several inches of wire to it so I could plug them into the empty connector slots of the z harness.

 

1) Insert new pin into slot 12 of ECU connector then cut wire 33 y/l before it goes into ECU connector and attach to new pin #12. So 12 pin from the Z31 ECU thru wire 33 y/l will be connected to the 12 r/w wire on the MAF (marked as F). Now the ECU will be able to go into auto clean mode and keep the NAF filament clean.

2) Insert new pin into slot 34 of ECU connector then connect it to a new wire going to the + coil terminal

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

 

 

CONNECTING THE FPR TO THE Z31 ECU:

This way if the car stalls out, the fuel pump should shut off as it’s supposed to.

Now on the 280zx the FPR is always grounded and does not get turned on until the ECU thru pin 16 l/r (blue wire with red line) sends a + signal. On the 300zx it is reversed, the + is on whenever the ignition is on, and the ECU thru the fuel pump modulator sends the – signal to activate the FPR. Hence, I needed to rewire the + and – signal used to turn the FPR on.

1) Black wire (- source used to turn on relay) wire cut right before FPR, connect to new wire and take to pin 108 on the ECU connector

2) 16 l/r ( + source for turning on relay), wire cut right before the ECU connector end and connected to + ignition source (I tapped into the b/w wire going to my 280zxt fuel pump modulator which sits above the ECU).

 

Now the ECU controls the – power that switches the FPR on thru the ECU pin 108, and the 16 l/r wire is ignition + to the FPR. Now I have no explanation for this part, but according to the book, pin 20 from the Z31 ecu should activate the FPR, which then loops back thru the FPR to pin 108. This did not work for me. However, it worked perfect when I connected the new wire going to pin 108. Again I don’t know why pin 108 is working for this and pin 20 did not, but it sure is working well on my car.

 

Also I disconnected the knock sensor and did not switch any of the injector wire.

 

Lastly, to run the air regulator, it was controlled thru pin 108 on the z set up (which control the FPR in the z31 set up) as opposed to pin 16 on the Z31 set up. So I connected the 16 pin/wire coming out of the ECU connector to the 108 z harness wire (black which goes to the air regulator) and now the Z31 ECU will control the air regulator from ECU pin 16 thru the 108 wire. (While ECU pin 108 now controls the FPR)

 

I hope this helps others map out there own swaps (there are many ways to do this). It would be most useful if others who did this could add in their tips, cautions and related experience reguarding this swap such as Z31 maps/ chip burning, adaptations for 370cc injectors, data on actual HP/torque gain and timing/tuning for the set up…..

 

 

Thanks a lot for this, its really going to help with my swap, after i finish the exhaust and intercool piping, i have to start on this. I remember seeing it before, didnt think it would be necessary. Happy Tuning!!!

[phil280zxt]

I'm finally getting a chance to embark on this swap this weekend. But before I do, I have a question for those you have already completed it in past. Over the years, whenever my 280zxt is not running correctly, the problem is very quickly corrected by reseating the ECU plugs. I've been tempted to replace my 280zxt ECU connectors with 300zx ECU connectors because they supposedly grip better, but I was hesitant to start hacking up my wiring harness. While reading this and other posts regarding the ECU swap and the need to "cut open a donor connector" to get a few additional pins to complete the swap, I was wondering if the pins can be removed from the existing harness connector and transferred (inserted) into the new 300zx connector in the proper locations. This would accomplish two things, 1) not require cutting existing ECU wires because the pins from the harness can just be inserted into the correct position on the 300zx connector and 2)replacing the 280zxt connector with a better fitting 300zx connector.

 

So my question is, does anyone know if the pins can be removed from a 300zx ECU connector without destroying the connector?

Edited February 20, 2012 by phil280zxt

[Daphur280]

I'm finally getting a chance to embark on this swap this weekend. But before I do, I have a question for those you have already completed it in past. Over the years, whenever my 280zxt is not running correctly, the problem is very quickly corrected by reseating the ECU plugs. I've been tempted to replace my 280zxt ECU connectors with 300zx ECU connectors because they supposedly grip better, but I was hesitant to start hacking up my wiring harness. While reading this and other posts regarding the ECU swap and the need to "cut open a donor connector" to get a few additional pins to complete the swap, I was wondering if the pins can be removed from the existing harness connector and inserted into the new 300zx connector in the proper locations. This would accomplish two things, 1) not require cutting existing ECU wires because the pins from the harness can just be inserted into the correct position on the 300zx connector and 2)replacing the 280zxt connector with a better fitting 300zx connector.

 

So my question is, does anyone know if the pins can be removed from a 300zx ECU connector without destroying the connector?

 

I'm using a 300zx harness for mine, however I'm removing every connector and re-looming the wires to best fit the 240z chasis/engine bay. I too am embarking on this--this weekend, if I get to it before you receive an answer, I will let you know if they appear to be able to connect to the 280zxt harness.

 

What year ECU/Harness are you using?

Edited February 17, 2012 by Daphur280

[phil280zxt]

I'm swapping an 84 ECU into my 81 280zxt. I would love to be able to swap in the 300zx connector while doing the ECU swap by transferring the pins from the 280zxt harness connector to the new 300zx connector, rearranging the pins that need to be moved for the ECU swap. This way, I don't have to splice as many wires, just move the pins around. Cant' wait to look into this tonight when I get home!

 

BTW, I found a blog which partially confirms the ability to transfer the pins. Looks like the 280zxt connector will be damaged in the process of removing them, but the 300zx connector has a couple of tabs that will allow the connector pins to be removed or inserted.

 

http://carlosransom.blogspot.com/2011/01/z31-300zx-ecu-connector-swap.html#comment-form

 

Good luck and let me know what you find.

[phil280zxt]

Followup on my prior post/question regarding the harness connectors. I've been able to remove the pins from the 280zxt and 300zxt harness connectors without causing any damage to the connectors. The pins look identical. This means that you can remove the pins from the 300zx connector that will connect to existing leads in the 280zxt harness and swap in the pins from the 280zxt harness without having to splice the wires. I kept the new 3 pins needed for the upgrade in the 300zx connector. This way I will get the benefit of using the better 300zxt connector without having to splice the original wires.

 

I had to destroy a connector to figure out how they are held in. It is really quite simple. There is a third row of openings that run down the middle of the bottom of the connector. By inserting a proper sized (very small eyeglass) screwdriver into the slot it will release the metal clip holding the pin in the connector.

 

I can see why the 300zxt connectors maintain better contact then the 280zxt connectors. The holes the pins pass through are smaller in diameter to better center the ECU pin and there is also a plastic insert which keeps the pins/wires in place. I will post pictures later.

[FricFrac]

That would be great. If you can get some detailed pictures as well I'll see if I can source replacement pins for the connector itself.

[phil280zxt]

Just completed the 300zx ECU/MAF swap tonight. Z started right up and settled down to the best idle I've ever heard! FYI, I was able to transfer all the pins from the 280zxt harness to the 300zxt connectors, so I get the benefit of better connections as part of the swap too!!

[DuoWing]

It's been a little while, but I was wondering how do you remove the pins from the third connector. It's the one with the slightly larger pins and the 300ZX version has that purple plastic piece around it. I can't figure out how you dislodge the pins from them. I got one out after bending the crap out of the pin, but I can't figure out how it releases.

 

Edit: Nevermind, I figured it out. It was actually easier than the other two. Do you happen to know what size screwdriver you used? I was trying and trying and could not get the small pins out with any screwdriver. I finally kinda figured the trick out using a safety pin. I had to push the pin inwards, then use the safety pin's point and then work it and finally could then slide the harness pin back and out. The bigger ones I was able to just use a large paperclip that I straightened, push the harness pin forward, put the paperclip through that top opening push it in as much as I could then slide the harness pin out.

Edited June 2, 2012 by DuoWing

[DuoWing]

I just did this same thing. I finished swapping the pins from my 280ZXT harness over to the Z31 connectors that I removed the pins from. Haven't tried the car out yet as I have some other wiring I'm messing with, but the connections to the ECU seem to click in better and the pins do sit much tighter. I tried to grab some pictures to help people out. I grabbed these with my phone so not the greatest/highest of quality.

 

 

Here's a back shot of the connector with no pins in it. This is the 280ZXT Connector, but very similar to the Z31 Connector. The upper row is what I'm trying to show. You can see the tiny holes at the end of each tunnel is where the ECU pin will connect into the harness side pin. The longer rectangular hole on the bottom of each tunnel is where the pins latching tab goes through to hold it in place. That's also leading into the little access holes for removing the pin.

 

Here's a front shot of the connector with a pin I popped back in. The middle larger holes are where you can place your screwdriver to push the latch in to release the pin.

 

Here's kind of an idea as to what you'll be doing. I found a 1/32 flat head screwdriver I picked up at Sears worked the best for popping the pins out. About the biggest size you can use is the 3/64 which I ended up using for the slightly larger pinned 3rd connector which I'll grab some pics of later.

 

Here's a shot of one of the pins itself. The tab sticking up is what locks it into place.

 

 

Finally here's an idea of what you have to do. You place your screwdriver down the access hole in the middle of the connector, the pin would be in this position on the bottom half of the connector. This pin would basically just be flipped so that the locking tab would be facing down when it's on the top half of the connector.

 

 

Essentially you push the screwdriver down the access hole in the front to try and depress that locking tab. Once you've got it pushed in enough you can then grab the wire from the back of the connector and it will pull out. It doesn't just fall out and takes a little bit of a pull, but if you're yanking and it's not coming out it's not loosened. The best way is to push the pin as far forward into the connector as you can while pushing the screwdriver towards the locking tab. The hardest part is just figuring it out, once you kind of get the hang of it it's pretty easy.

[phil280zxt]

That's the same process I used Duo. It's fairly easy once you get the hang of it. I straightened out one leg of a paperclip and flattened it with a hammer until it fit into the connector opening.

 

FYI, I've put about 800 miles on my swap and my Z has never run better. Better idle, smoother acceleration and quicker accelleration. I won't comment on any perceived HP increase, but it does seem to move along quite nicely now....

Edited June 4, 2012 by phil280zxt

[DuoWing]

I'm really hoping changing the connectors helps for me. My car has been acting up lately, and it seems that I can shake the ECU/wiring harness and it will stumble. So I need to mount the ECU better, and the much tighter, better connections should help. I'm trying to find some better lighting to take a picture of the third connector and pins

[cgsheen]

That's the same process I used Duo. It's fairly easy once you get the hang of it. I straightened out one leg of a paperclip and flattened out out with a hammer until it fit into the connector opening.

 

That's exactly what I did! Paperclip flattened to make a custom pin release... I'm using an Infiniti M30 ECU - isn't it amazing what a little better engine management can do!

[DuoWing]

I have an M30 ECU lying around that I picked up for cheap. I'm actually considering swapping over to that at some point.