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Wiring almost done for Z31 MAF!

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  • Wiring almost done for Z31 MAF!

    I'm finishing up on swapping from my restrictive flappy door AFM to the modern 1984 MAF EFI. This is on my 1976 280Z 2+2 with an '81 L28et. I used the 1981 Jecs ECCS for a while, but I found it to be too unreliable and tended to lean out at crucial times for no aparent reason. One day it ran good, the next day it leaned out and misfired. It usually ran overly rich to the point where I went through spark plugs every month or so. I tried to fix this with new parts and AFM adjustments, but nothing helped!

    Jason, who is in my local Z car club (mechanically seperated chicken????) convinced me to do this swap. This should remedy my problems.

    I used crimp-on connectors in case I had to remove any connections (which I did!). I'll tape them up later.

    Believe it or not, the connectors for the 81 and 84 ECUs are the same! They just have different pins and the 84 ECU was mounted on the wrong side for my car so it faces the kickpanel.


    I had to modify a 1982-83 280ZXT splined shaft dizzy to work with my '81 slotted oil pump shaft. For those of you who don't know, 1981 ZXTs used a magnetic CAS that reads from magnets on the crankshaft damper. The 1981 distributor was just a "blank" that only contained a rotor. That was a one year thing as the 82-83 models switched to the photoelectric eye you see before you.

    Next, I have to install a Z31 chopper wheel to work with the '84 ECCS.


    The MAF wiring was pretty straight forward, except for the cleaning wire. I need to rig up some switch for that later.


    I couldn't have done it without my beloved big ball 'o wire from a 1981 280ZXT in the junkyard. I got her over a year ago because I wasn't sure of which wires I needed for the '81 turbo swap. My dad and I ripped out most of the wires in the dash. Smartest mistake I've ever made, although she isn't as fat as she used to be. :lol:


    Really it was quite simple once I got into it. I just added a few pins and ignored most of them. I have a lot of pins for idle control devices that I don't need or understand.

    How do I keep this out of limp mode? I'm mostly going to run the bare essentials (ECU, MAF, FPR, etc.) and maybe an air regulator. Do I need a fuel temp sensor to keep it out of limp mode? Are there any other precautions/things to consider?

    I'll be sure to post up my results later, but everyone who has done this swap has reported awesome results, even on properly running systems.

    Feel free to ask/answer questions!
    1976 280Z 2+2 Turbo
    '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
    "I drive an S30...your stock equipment is my future upgrade!"

  • #2
    as far as limp mode goes i think all you'll really need is the maf, cas. you will need some of the other sensors for everything to work properly . since it's an 84 computer and your not able to program it i would at least get the o2 and the tps working properly as well. it's definitly a cool project keep us updated.


    boost. does a body good!

    Comment


    • #3
      Very cool! Looks like it's coming along nicely, I bet you can't wait to fire it up.

      jjewell wrote: since it's an 84 computer and your not able to program it i would at least get the o2 and the tps working properly as well.
      O2 should be the same as his car, and the 84-85 ECU's are now programmable via NisTune and a special modification/installation. Yes, this means you can now reprogram any Z31 ECU. The 88-89 are just far easier to install and have a better code to begin with.

      Comment


      • #4
        OH shizit i didn't know the earlier ecu where now programable. what's the process for setting them up ? romulator or something simular?


        boost. does a body good!

        Comment


        • #5
          you have to bypass the 24 pin rom.... so it reads only the 28pin one, which is what rommy and nistune interface with, plus nistune taps into a few leads on the processor and such

          due to the chts fix in the 87+ ecus it's probably still best to stick to at least 87 if you can't get 88+

          Comment


          • #6
            I need to bypassing the dropping resistors

            Can someone tell me exactly how to bypass the dropping resistors on the 1981 ECCS harness? I asked on Zcar.com, but by the time people stopped arguing about the fact that 81s had resistors and 84s did not, it was already at the bottom of the page. The only semi-helpful comment I got was "just run jumper wires" and that was it. :roll:

            Anyway...

            1981 wiring diagram:

            http://www.autozone.com/images/cds/gif/ ... 1d1d9d.gif

            This is the plug for the resistors. Notice there are only 7 connectors.

            1976 280Z 2+2 Turbo
            '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
            "I drive an S30...your stock equipment is my future upgrade!"

            Comment


            • #7
              Going out on a limb here..

              any way you can fluke them out?

              7 pins, 6 injectors.. unless the resistor pack fed the injectors rather than going back into the harness... I've seen the pack before, just don't recall caring too much.

              ahh, just caught the diagram.

              ok, solid red is common +12v bus in
              the red/STRIPES are each individual injector power after the resistor.
              The ecu is providing ground (to fire the injectors) via the GREEN/STRIPES to each injector.

              to bypass, you have to basically take the solid red wire, and feed that 12v to the six others.
              vg33et -blew some chunks outta it, then gave it all away.
              2009 370z touring/nav/sports

              Comment


              • #8
                actually, looking at it a bit more, you can do a 'fuel injector campaign' style wiring here.

                take injectors 1,2,and 3, solder all of their red power wires together, and connect that to the single +12v, and solder all of their green/black grounds together.

                3,4,6, do the same.

                it'll be running banked out of the z31 ecu anyways.
                vg33et -blew some chunks outta it, then gave it all away.
                2009 370z touring/nav/sports

                Comment


                • #9
                  Alright, I cut open that section of the harness.

                  The computer tells the injectors to ground out, so I might as twist together that entire pack of wires and have it send + to all injectors all the time.

                  Does that sound right?

                  1976 280Z 2+2 Turbo
                  '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
                  "I drive an S30...your stock equipment is my future upgrade!"

                  Comment


                  • #10
                    sounds right, but don't just 'twist' them... solder and heatshrink them if you don't like the tow trucks..

                    your diagram is kinda...odd.. but it does look like you got it. I would have avoided the resistor pack on the bottom side, totally avoiding crossing the ecu GND line.
                    vg33et -blew some chunks outta it, then gave it all away.
                    2009 370z touring/nav/sports

                    Comment


                    • #11
                      Well, since it's a bunch of wires merging together, I can't really heatshrink these particular ones, but I'll be sure to solder then and coat them with that brush-on wire insulation.

                      I tried to avoid the use of electrical tape wherever possible.
                      1976 280Z 2+2 Turbo
                      '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
                      "I drive an S30...your stock equipment is my future upgrade!"

                      Comment


                      • #12
                        lol, yeah..
                        my friends used to ridicule me for spending ~3$ a roll for the good stuff too...

                        I didn't even bother trying to explain it to them.
                        vg33et -blew some chunks outta it, then gave it all away.
                        2009 370z touring/nav/sports

                        Comment


                        • #13
                          No fuel

                          I keep messing with the fuel pump relay, but I can't seem to get the fuel pump to run in "on".

                          The + signal wire is in pin 20 of the ECU and runs to a terminal marked "COIL" on the relay. The - signal wire also runs to a "COIL" termial and is connected to pin 108.

                          The fuel pump power wire is connected to "NO" and the power wire to the battery is connected to "COMM".

                          I get a small amount of voltage (.62 volts) through the + signal wire and the - signal wire seems to be grounded somehow.

                          I hotwired the pump by touching the battery and fuel pump power wires together and the pump ran fine.

                          How do I get the pump to run in "ON"?
                          1976 280Z 2+2 Turbo
                          '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
                          "I drive an S30...your stock equipment is my future upgrade!"

                          Comment


                          • #14
                            I just tried pin 16 for a + signal, but still no response.

                            I'm tempted just to hotwire the pump.

                            BTW, I'm almost done with the distributor. I decided to use the bearing, CAS, chopper wheel and some other hardware from the 300ZX distributor. It all swapped over nicely!
                            1976 280Z 2+2 Turbo
                            '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
                            "I drive an S30...your stock equipment is my future upgrade!"

                            Comment


                            • #15
                              I got all the wiring correct, aparently, because it just started up.

                              It only spun over twice before running. It normally takes a lot more coaxing, spitting, and sputtering! It seemed to rev a lot smoother.

                              EDIT: I just took it out for a testdrive. It runs gooooood! No bucking or missing in boost and it seemed to have more power! 40...70...80...it just kept going. :lol:

                              I also didn't smell a lot of fumes. FYI, S30s have terrible aerodynamics and tend to suck in exhaust fumes. Must be cleaner emmissions!
                              1976 280Z 2+2 Turbo
                              '81 L28ET, '84 Turbo ECCS, '84-'85 rotors + Toyota 4x4 front calipers + 240SX rears, Z31 DXD Stage I clutch kit, Evo intercooler, Tokico lowering springs and HP blues
                              "I drive an S30...your stock equipment is my future upgrade!"

                              Comment

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