NismoPick

I really didn't do too much research on the VCM... the Z31T ecu swap calls for removing it, so I did, and haven't had any probs. I did read somewhere on the interweb about a guy making some contraption to make the Z31T ecu control the AAC. It was far too much work for my time tho.

duowing

Alright maybe you can help me on this Nismo.
I started a thread over on Zcar.com, and I got a response about my ECU/MAF swap. Now the guy mentions that you need to have the ECU tuned, that you shouldn't just drop in a normal Z31 ECU being untuned for your car. He says that although the swap doesn't call for it, not running a fuel temp sensor could cause issues with the ECU. He was also mentioning like I've heard a few times that you need to swap injector wires 2 and 5 to get correct injection? This is something I can't figure out. I believe he also said to run the ECU swap with a 6A ignition.

If you can explain to me at all why I keep hearing about switching the injector wires that'd be cool. As for running the other sensors, I don't remember hearing about needing to run those, and as far as I'm aware we did the swap in the same method, just added the pins, swapped the few wires, and spliced in the MAF, and added the Z31 rotor plate and left it at that if I'm not mistaken. I also heard you need to run the Z31 FPR? Are you running a stock 280ZX FPR or an aftermarket FPR? I also don't know how you'd run the Fuel Temp Sensor.

Also came across this reading through the HybridZ original swap thread:

Afshin: A few more notes, for 280zxt with fuel pump modulators, it is now being bypassed, I forgot in the first post to remind you to ground your fuel pump to the chasis. (the relay will control the + line going to the pump).

Is this saying, that I should disconnect the wire going to pin 108 and just straight ground it?

NismoPick

Post a link of that thread... I'd like to read it.

duowing

http://www.zcar.com/forums/read/1/1883174

I went ahead and threw my original problem on there, hoping to see if I could find any new answers primarily about the AAC and such, but that was no luck.

I just realized that I never did ground the fuel pump the body. Will this affect anything? Or might that be the reason why my fuel pump stays running rather than doing the 2-3 second prime?

Alright I was talking to a friend about the swapping injectors and it wasn't until I typed it out that the injector swap made sense. I was originally thinking that why would it matter if it's firing injectors 1-3 then 4-6, but when I typed out how it would look. 1-5-3 then 4-2-6 then I realized that it would match up more with the firing order. It would batch fire 1-5-3 for the first half, then the 6-2-4 injectors for the second half. Probably not enough to make a drastic difference, but possible a little difference. I may try it out for the heck of it.

lifegrddude

From reading your post on zcar, it sounds to me like you have a vacuum leak somewhere in your system. Run some Seafoam through your vacuum lines, and see if any smoke comes out. Also check your connection to the turbo from the intake pipe. If your Z is running fine with cold start enrichment but not when warm, it points to a vacuum leak as the biggest culprit. Double check your seals on the fuel injectors too btw.

NismoPick

^^^ Indeed, gotta check for vac leaks... especially if you are still using those home made EGR / AAC block off plates. Make sure they seal very tight. Now for the rest:

Since you didn't say what year Z31 ecu you were using at first, JeffP (one hella smart guy & has an incredible 280zxt) was under the impression you were using the tunable 87-89 ecu. The 84-86 is not tunable. Fuel temp sensor not needed. Injector wire swap not needed (everyone who has done the Z31 ecu swap is proof... that swap mis-information came from a webpage explaining the wrong way to do the swap). And stock ignition can be used, or the Z31 ignition, or the 6A/L

You don't need the Z31 Fuel Pressure Regulator... the 280zx one works the same. You don't need Fuel Temp Sensor.

No... pin 108 needs to connect to the Fuel Pump Relay ground. The Z31 ecu grounds the relay, activating the fuel pump.

Yes, the fuel pump must now be grounded directly to the body.

No injector wiring swap needed.

duowing

Alright thanks for the info. Makes a little more sense. My problem is really weird the car starts up fine and when cold runs decent at first, but then before the air regulator closes it will start giving me a real lean hesitation with lean popping and all. Once the air regulator closes the car seems to run pretty decent except for idle. I switched back to the actual valves and made some cork gaskets, which seem to work, I'm going to have a person help me make a good block off plate so it will seal.

DriftZ83

i was told the 88" ECU was the most sought after one for this swap? duowing/nismo... is there a post on this forum for a step by step tech write up for this project? i didn't see one. one of you guys should post one cause i have been looking into this for my 83" ZXT but i feel like i'm missing pieces of information... a step by step would help SOOO much! thanks guys

duowing

http://forums.hybridz.org/showthread.php?t=91250

That's the best step by step, you pretty much just need to follow that exactly as it says and you shouldn't have any problems. The most I can add to tell you right off the bat is items to get are:

Z31 ECU - The 84-5 might include the 86 & 87s? ECUs are the best to get primarily because they swap over with just a few wire splices. Work with the existing 280ZX O2 sensor, etc.

The 88-89 later ECUs are better because they can be tuned and include 16-bit processors making them more advanced and what not, but these will require you to have a bung welded on to your downpipe or at least have the downpipe modified to fit the later model 3-4 wire O2 sensors. Not to mention the wiring is just a little bit different.

It's good to get the wiring connectors with a few inches of wire so you can cut open the Z31 connectors and grab the ECU pins from them.

Z31 MAF - This can be obtained from any year 84-89 Z31. You also need the MAF wiring connector and probably a few inches of wires so you can splice it into the harness. Also one thing to note that I encountered in my swap, for some reason the wiring connector to my Z31 MAF had only 5 wires when it was supposed to have 6, it was missing a pin, I'm not sure if this is a difference with the Turbo and Non-Turbo or what, so I had to cut up the connector from the 280ZX AFM and grab a pin from that and plug it into the MAF connector.


Z31 Crank Angle Sensor Rotor Plate - it's really similar to the chopper wheel/rotor plate in the 280ZX CAS, but it has an extra hole in it to help mark the timing position.


I'm at some point down the line planning to upgrade to a later Z31 ECU, but that will be later on and once I have my car running a bit more to my liking. The swap does seem to overall make the car run better, smoother, and give you better throttle response, as just all around power seems to be improved as well.


A few other notes to go with the swap:
- Z31 ECU controls 280ZXT VCM incorrectly so you should unplug it, then you can remove the VCM if you want. VCM controls EGR and AAC.
- Fuel pump should now be grounded to the body

NismoPick

EDIT... DuoWing got to it first.

Welcome to ZDriver! The 87-89 ecu is usually the one people want as it is tunable. The swap is a bit diff than the 84-86 ecu tho.

Here's a bunch of links for you from this recent thread: https://www.zdriver.com/forums/280zx-s130-forums-77/why-did-they-use-afm-24645/

duowing

Come join the ECU swap club!

DriftZ83

so u take the pins out of the z31 pins and put them into the zx connector but then your still using zx and z31 connectors... don't u just splice in the z31 pigtails? i don't even know what the aac is or stands for... i'm not behind the times on the lingo, i'm up on the latest tho, lol. thanks guys

NismoPick

It's all been laid out. Click on those links. If you feel like doing a lot of unnecessary work, you can cut all the wires and re attach the z31 ecu plugs. You don't need to do that on the 280zx turbo (just the 280zx n/a... or use a Z31 harness).

AAC = Auxiliary Air Control (actuator on the intake by the emergency release (pop off) valve.

DriftZ83

so as i'm reading i wouldn't even need to connect the terminal at the ecu that controls the aac if it doesn't even work.

NismoPick

Download this: ( from our documents thread https://www.zdriver.com/forums/site-brainstorming-259/documents-thread-21185/ )

Zip password is turbo. The Excel spreadsheet should help you put it together. Wiring is VERY easy... only 2 pins need to be added to the ecu plugs (#12 & #34).

DriftZ83

wohie woh woh... thats perfect! i just need to see things neatly put together and in order. what about ignition coil pin #3?

NismoPick

I found out after I put that spreadsheet together that you only need pin# 3 IF you are using the Z31 ignition coil. If you are going to keep the 280zxt coil you don't need to add that pin or run that wire.

DriftZ83

cool then... just to clearify this... do i need a turbo Z31 ecu or will an n/a Z31 ecu work? what about manual for auto? i have a manual ZXT so i would assume i need a manual turbo Z31 ecu? also can i replace just the cas or do i have to replace the entire dizzy? i have had Z31 guys tell me that i have to replace the entire dizzy... ture? u guys are a ton of help thanks!!

lifegrddude

In the links provided you'll find everything, but yes a turbo ecu is a must, unless you are planning to get it reprogrammed. If that's the case, then a late model n/a ecu is probably the way to go since you don't have to worry about wiring in a 3 wire o2 sensor. Just don't use the n/a ecu untuned. It will run rich, and also won't pull any timing as you enter boost. Anyway, you only need the chopper wheel in the dizzy from the z31. You'll see the metal plate after taking off the top cover. Good luck with the swap man, you'll definitely like the increase in driveability, not to mention less electrical gremlins as well.

duowing

You don't need to replace the dizzy or the Crank Angle Sensor. You just need to swap over the rotor plate. Not the best picture, but this is what it looks like:



The 280ZXT rotor plate looks almost the same except it has one less hole in it. As for the Wiring Harness you just cut up a Z31 ECU connector and pop the 2-3 pins right into the existing 280ZXT connector. They just push and click in and then all you do is run the wiring from that pin to where you need to go. It's actually really easy.

As for the VCM, AAC, EGR stuff, you would still have everything connected at the ECU like normal, you would just go into the engine bay, right by the radiator, near the AFM there's a little control unit with 4 vacuum lines on it and two electrical connectors and you can unplug the two electrical connectors from that. Otherwise the ECU will kind of randomly open and close the AAC.


As far as I know the manual and auto shouldn't matter that much. There's as far as I'm aware very little difference between the two if any. Just worry about getting a Z31T ECU, I've never heard anyone make note of whether it was auto or manual.

DriftZ83

ok thanks... what ecu did u get... auto/manual?

snwbrderphat540

hey guys, does it matter what year turbo Z31 you use? cause i JUST remember i have an i think 87 right in the local J yard with motor and everything still in it. and a huge wasp nest and i might just gank the stuff cause it was sitting at the entrance last time i saw. id get the rear diff to but thats a bit of work....

DriftZ83

84'-85' is the easiest and the 88' is the best cause it's tunable but harder to find and is worth more money cause they didn't make very many turbos. what about the knock sensor... does anyone diconnect those?

duowing

I have the knock sensor disconnected on my ZXT, it's still there, just not hooked up. I disconnected it at one point to see if it would make any difference and I found no difference. As for what ECU I have I'm not sure. All I know is that the Z31 ECU I bought was from an 84 Turbo, I got it off Heat Rave R

lifegrddude

Snw, you can use the 87T ecu, but I believe that was the year they also switched over to the 3 wire o2 sensor. Best bet is the 84-86T, or if you plan to reprogram, grab an 88-89 n/a ecu. Just get the chopper wheel and MAF for now, and pick up an ecu down the road. Oh and the knock sensor isn't used with the Z31 swap. Just disconnect it as it won't function correctly anyway. Not that it was much help on the stock efi either though.