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Z31 swap onto '81-83 turbo motor (write-up please, someone?)

Guest bastaad525

By Guest bastaad525
in Turbo / Supercharger

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Guest bastaad525

Guest bastaad525

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Okay I think someone HAS posted this info before... search function is busted so I haven't been able to find it.

 

 

Can someone please do a detailed writeup on exactly how to swap over to a Z31 ECCS on a first gen turbo motor? Or link to a writeup if you've already done one?

 

Details I'm looking for are:

 

Exactly what parts are needed, i.e.: ECU, MAF, and which parts can be kept, i.e.: can it work with the AFM? What about the distributor? Which sensors are compatible? Which wiring harness to use?

 

What options are there? i.e.: again, can you use either the MAF or the AFM? any other things that will work fine two or more different ways?

 

and lastly, wiring, what wires need to be changed, spliced, reordered, any new wires need to be hooked up? Can either harness be used?

 

This swap sounds like a great swap that will result in a great running turbo, much more flexible than the stock ECU, and w/o all the hassles (like tuning and programming) associated with standalone programmable units. I think it'd be great if someone could really get all the details down on this swap and then the mods could make it sticky so that people can always be able to reference that and know that there is a good alternative, in the same way Moby's MS'n'S writeup was stickied.

 

 

Can one of you guys please take the time and do a really detailed writeup on this for us? okay okay well for me? :wink: after looking at all the options and seeing how my car behaves on the dyno I think this would be the most reasonably priced easiest swap to do for me and would work perfectly for my setup and would really like to know exactly what it will take to get it in my car and running.

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Tony D Rookie

Tony D

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Ain't gonna be Moby! He already has programmable spark and fuel in the car using Megasquirt-n-Spark for a reasonable cost.

 

Hell, for the two or three hours spent tuning the car to run right, you may not even FIND all the Z31 conversion parts in the JY! Tuning is not that big a deal, especially if you have a dyno access with an AFR readout.

 

Most with MS are running in a few minutes, and driveable soon thereafter. Usually within 2 hours of seat time tuning you have a vehicle that runs at least as well as stock, but with better fuel economy!

 

And when you add boost, or injectors, or intercooler, you simply retune by tweaking the effected bins. Not so easy on a Z31 ecu...

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Guest bastaad525

Guest bastaad525

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so you think getting and assembling an MS, including all the wiring and such, getting it installed and tuning it would be easier than doing an Z31 ECU swap? How does it compare to doing an MS install WITH the spark control too? I had considering doing MS just for fuel but didn't like the idea of two ECU's running. Also considered doing MS for fuel and switching to an N/A ZX dizzy with the external module to control spark though that seems kinda limiting and potentially dangerous.

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mobythevan Newbie

mobythevan

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but didn't like the idea of two ECU's running

 

Only takes one MS ECU to do fuel and spark. Sleeper and others know the Z31, so you'll have to get with them. It probably takes more time up front to get the MS installed, but you have more control with it when it is in. Sometimes having more knobs to turn only leads to confusion. :D

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SleeperZ Newbie

SleeperZ

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At this point, I do not have the time to do a formal write-up on what is needed for the conversion.

 

I used a '86 turbo ECU; others have used later models, some non-turbo. I wanted to use the turbo ECU because I didn't know the difference between the fuel and spark curves, and I didn't feel like experimenting. The later model turbo ECUs use an expensive O2 sensor, '86 and earlier can use the old unheated type.

 

The MAF can come from any Z31, turbo or non. I believe they are all the same. The one I used I made sure had the idle mixture adjustment screw; some don't.

 

I was never sucessful connecting the knock sensor - I looked on Z31.com, and most people just connect one wire of the two to avoid getting a code. I wired in the fuel temperature sensor, mostly to avoid getting a code, don't know if it's needed - I suspect not.

 

The fuel pump is controlled differently on the Z31. I rewired my pump and relay as documented in the Chilton's manual ('70-'89 Z and ZX). I highly recommend this book for the wiring diagrams.

 

The CHT, TPS and CAS can all be used by the Z31. The slotted wheel from a Z31 distributor will bolt into the 280ZXT distributor ('82-'83) - it has a wider slot for #1 spark plug, presumably to mark a TDC reference to the Z31 ECU not used by the 280ZXT ECCS.

 

As far as wiring, you have a few options. Some have used the existing harness from the 280ZXT, even using the AFM connector to wire the MAF. This requires the defeat of the keying to make it fit, and if you wire it wrong, the ECU is toast. I used the connectors cut from the Z31 ECU and MAF, and spliced them into my '82 harness. Lots of soldering. Another option is to use the Z31 harness, which may require relocating the ECU to the passenger side of the car, I'm not sure.

 

Hope that helps.

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Sean73 Newbie

Sean73

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I used the Z31 harness, and mounted the ECU on the driver's side kick panel. This created an excess length of wiring, so I had to trim to fit, and install new connectors everywhere.

 

A formal write-up is just too long of a project. Basically, I got the 73 240Z wiring diagram, and the 84 ECCS wiring diagram, and taped them together. Then, it became intuitive how the two setups would be merged, with only a few wires connecting the two. I replaced the 84 ECCS fusible link box with a maxi-fuse block.

 

After pulling the 84 harness, I spread it out over the living room floor, unwrapped it, and checked, and labeled every connection according to the wiring diagram. This was a good exercise, and learning experience.

 

The wiring harness is installed, and trimmed to fit. It's so nice not to have to install that flapper AFM, which is a tank, and takes up too much space in the engine compartment. I am just waiting for my downpipe to be coated, and I can fire it up. I'll let everyone know the results.

Sorry not to be more of a help, but this is really a mod that requires a full understanding of the wiring, not a step-by-step recipe.

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Tony D Rookie

Tony D

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I was in the same situation as you Baastaad! I didn't want two ECU's running. Then an 81 turbo engine landed in my lap, and I had a 260 with no motor... So I was going to just slap in one of my MS units, and go with a conventional BTM on an MSD6A.

 

Then the MS-nS was revealed to me, and my mind was made up.

I recall it was only the second week of December when I said Id' try it and let Moby know if the wiring did work on the 81CAS the same way it does on an 82/83. Now, being anal about wiring and shrink wrap elongates the project, and replacing bolts cause their dirty, etc etc etc has made the job go long, but the wiring of the boxes would have taken maybe two days in the driveway if I'd had an already running 81 setup in the car.

 

Were I to do it again, I would parse the OEM harness, as it has a lot of good parts and is already wired nicely.

 

The MS took me 5 hours start to finish to solder together. The relay box about 45 minutes. Case mods for everything took another hour, and a lot of that was figuring out how I wanted to do what I needed to do.

 

But in the end, you have totally tuneable EFI and Spark. With the ability to incorporate WBO2 control! For that I figure it's worth it.

 

When I do the TBI 260Z, I will be buying a new 82/83ZXT CAS, and replacing the distributor currently in the car. I will then have MS-n-S running fuel and spark in the 260 which from external cursory glances will look stock... Muahahahaaaa how big of a cam can I run again and have a smooth idle with EFI..... "Yeah, it's stock. Yep, those are the factory Flat Tops. Yes, the AIR pump and AC work, don't you see the belts on them?"

 

Muahahahahaaaaaa... :D

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Afshin Newbie

Afshin

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Hi

well I'm in the process of putting in the Z31 ecu/ams in my car. If I finish it and it runs in the next couple of weeks (I'm busy with work as usual), then I will do a full write up including photos of which wires to cut and splice, including rewiring so the fuel pump relay works as intended. I'm using a 84 set up with the stock 280ZXT harness.

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Guest bastaad525

Guest bastaad525

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LOL sometimes... the more I read... it occurs to me that doing EITHER one is probably over my head. This whole damn turbo swap project has been over my head... I miss my SU's.... 'slow' as they were.

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Guest bastaad525

Guest bastaad525

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Just put a damn bowtie in it and be done!!! :twisted:

 

 

ya know if I could I would. I'm SO out of money as far as this car goes, and I'm stuck with what I've got, though every day I'm more and more tempted to sell it and see if I can't hussle up enough cash from the sale to buy an already-done V8 swap. I wouldn't dream of doing another Z from 'scratch' though. I've got to get my life back on track, move out of this apartment and buy a house, etc, and those things will never happen if I keep dumping money into this car. If I were going to spend the kind of money and time you've spent on yours I'd just build one of the factory five racing AC Cobra replicas... I've met three guys so far who've built those using one late 80's mustang as a donor car and when all was said and done were less than $20,000 in for a finished, driveable car.

 

Anyways... spent the better part of the last two days chasing down this fuel smell to no avail... I figure it HAS to be one of the couple hoses left that I haven't changed going to the vent tank... gotta drop the fuel tank to get to those. When we buy my wife another car hopefully in the next week or two I'll just 'inherit' her Honda and the Z just gonna keep sitting.

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