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motronic basic 1.0 ETA to megasquirt

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    motronic basic 1.0 ETA to megasquirt

    so im wondering what would it take to keep my same 35 pin harness and run megasquirt

    im thinking i would fabricate a 35 pin adapter harness to plug ms in as well as run new wires for sensors ect

    my reason for all this is because i would like to be able to swich back and forth between motronic and ms with a minimal amount of work should the situation arise as my excisting wire harness is in good shape and my motronic ecm is new

    so what would it take ? what sensors would i need to install to become ms operational? as well as keeping motronic operational as well ?

    #2
    I want to do the same thing for a M20b27.
    I just started reading related topics and guides.
    From what i understand you can use every sensor except the crank position sensor and AFM. Also the cilinder id sensor is missing on this harnass but it's optional.
    It is recommended to replace the O2 sensor with a wideband O2 sensor. For example the LC-1 (this sensor is also compatible with motronic 1.0).

    The AFM can be replaced with a MAP sensor which is build in MS. All you need to do is run a vacuum line to MS.
    If you remove the AFM completely (like me) you need an extra IAT sensor. You can take the one from inside the AFM but it is easier to replace it with a GM open element IAT.

    The CPS can be replaced by the cps from a m20b25. You need the sensor and the toothed wheel. Both bolt straight on the M20b27.

    I'm trying to figure out the wiring. Any help is welcome.

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      #3
      that deff sounds viable -
      im going to have to research the function of cyclinder ID sensor , if it can be added, or if its much of a detriment to leave it off - will get back with that info
      from what i understand, the way the fuel injectors fire off is different on motronic basic in that they all fire off at once vrs batch fire this may in some way relate to cyclinder id sensor idk tbd (?)
      as far as ms to basic motronic wiring - um yea that could be an issue where ive compared the pin outs and not much similarities found so fabricating a 35 pin to 55 pin ms plug n play adapter is a sticking point for me the other option as i understand it would be to cut the plug off and simply wire in ms that option isnt really the way i want to go as i would prefer to switch back to my (new) motronic basic should the need arise

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        #4
        bump, possibly looking into making one of these adapter. The only thing that wasnt addressed above was the toothed wheel for the CPS and the vTPS.
        318iS Track Rat :nice: www.drive4corners.com
        '86 325iX 3.1 Stroker Turbo '86 S38B36 325

        No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

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          #5
          Bump for progress?
          [/url]

          Team USA Wrestling 67KG
          Team USA Wrestling Strength And Conditioning Coach

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            #6
            Another bump, wondering the same. I'm doing the 885 head swap on my eta and would like to keep the stock wiring harness if possible and just wire in the sensors separate if need be.. I have all the sensors I need (vTPS, toothed crank and sensor, IAT incoming..) so I'm assuming at minimum I'd just need to get creative with wiring up the sensors to MS.

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              #7
              yeah you need to wire in the toothed wheel and cps and of course TPS but I think it could be done after studying the pinout diagrams.

              etadriven the stock 35 pin ecu will not work because the injectors on the m20b27 are low impedence vs high impedence on the m20b25 173 ecu
              318iS Track Rat :nice: www.drive4corners.com
              '86 325iX 3.1 Stroker Turbo '86 S38B36 325

              No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

              Comment


                #8
                It depends how hard core you want to go. I am converting my m20b23 L-jtetronic to Megasquirt. The L-Jetronic is the simpliest M20 fuel injection, very old school. not many wires at all.

                I tried to incorporate the oem harness, but eventually i just decided to bite the bullet and make a whole new harness, custom made. OEM was just missing too many wires.

                New bosch plugs, lume tube, db37 plug, a whole lot of soldering, self amalgamating tape etc.

                This allowed me to use any sensor i want anywhere, wire it in semesequential (2 groups of 3), proper TPS plugs, put all of the outputs into the loom. It should make for a neat install.

                These photos show it probably 75% done, I'm almost there.

                Oh and i used a 60-2 wheel and sennsor from an m20b25, bolt right on:)
                Attached Files

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                  #9
                  Originally posted by downforce22 View Post
                  yeah you need to wire in the toothed wheel and cps and of course TPS but I think it could be done after studying the pinout diagrams.

                  etadriven the stock 35 pin ecu will not work because the injectors on the m20b27 are low impedence vs high impedence on the m20b25 173 ecu
                  Megasquirt can drive either type of injectors, although high impedance are far more common. You just need to set it up differently. Or swap them out - don't know if the connectors are different.
                  Build thread

                  Bimmerlabs

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