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E30 with S50 and E30 M3 cluster - tach coding plug

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    E30 with S50 and E30 M3 cluster - tach coding plug

    Have an E30 M3 cluster I'm going to install in my S50 powered '88. I seem to recall the S38B35 coding plug being the correct unit to use, to keep the tachometer accurate, but cannot remember for certain. Is this correct? Been a long time since I was considering doing this and I finally bit the bullet and bought a cluster...

    I know the 325i coding plug will get me 87.5% there, but I don't want to do that....
    Autobahn Motorsport - Portland, Oregon
    @autobahnmotorsport
    '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

    #2
    I believe you are correct, the E28 M5 coding plug is needed to take advantage of the higher range tachometer. I also remember that the circuit board needs removed from the plastic housing so that it will plug in to the E30 cluster.

    I have not yet done this modification so take my comments with a grain of salt.....hopefully someone who has actually done this will respond. My E30 M3 cluster has not yet been installed but maybe this thread will motivate me to grab a M5 coding plug and give it a try.


    MJ

    Comment


      #3
      I found the thread where I originally got my info:

      https://www.r3vlimited.com/board/for...for-tachometer


      You can see it has a different shape in the pictures at the link below:

      https://www.ecstuning.com/b-genuine-...g/62111377664/



      Hope this helps.


      MJ

      Comment


        #4
        I did this earlier this summer with good result. Same motor/cluster. The e28 m5 coding plug works but you have to take the pcb out of each plastic housing and swap the chips. There may be an aftermarket solution for less money, I dont recall.

        Comment


          #5
          Ya I recall seeing a seller on eBay selling aftermarket coding chips (if you can’t find a OE one I suppose, just figured I’d mention). Sent from my iPhone using Tapatalk


          1992 M tech 2 Convertible - S50 Swap
          1992 e34 Touring- S50 Swap
          1992 325i-S50 Swap

          1995 e36 M3 Mugello Red - S50
          1991 325i Convertible Laguna Green (SOLD)
          1987 325i (SOLD);1992 M tech 2 Convertible (SOLD)
          1988 325i Convertible Alpine White (SOLD)
          1991
          Brilliantrot Convertible 80k Miles (SOLD)
          1992 325i Convertible Schwarz (SOLD)
          1992 318i Convertible Project-Finished (SOLD)

          Comment


            #6
            Awesome, I guess my memory didn't fail me for once. Thank you, all!
            Autobahn Motorsport - Portland, Oregon
            @autobahnmotorsport
            '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

            Comment


              #7
              FWIW, I ordered an e28 M5 coding plug from the dealer this morning. They had a few of them in the warehouse, in Stockton, CA, and they were $50/each. Kinda surprised they are still available.
              Autobahn Motorsport - Portland, Oregon
              @autobahnmotorsport
              '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

              Comment


                #8
                Originally posted by e30austin View Post
                FWIW, I ordered an e28 M5 coding plug from the dealer this morning. They had a few of them in the warehouse, in Stockton, CA, and they were $50/each. Kinda surprised they are still available.
                It is strange considering what they make NLA and is in demand. I'm sure BMW is wondering why they are selling so many coding plugs for a car they only imported 1200 of for one model year....who am I kidding I don't think they pay attention.


                I did find this ebay seller that has "plug and play" boards. Not much cheaper than the OE part and possibly more risk:

                https://www.ebay.com/itm/NEW-BMW-E30...-/253954109934


                Make sure to post back once you get the part and go the install. It would be great to get more details on what is involved using the factory part.


                MJ

                Comment


                  #9
                  Originally posted by mjweimer View Post

                  It is strange considering what they make NLA and is in demand. I'm sure BMW is wondering why they are selling so many coding plugs for a car they only imported 1200 of for one model year....who am I kidding I don't think they pay attention.


                  I did find this ebay seller that has "plug and play" boards. Not much cheaper than the OE part and possibly more risk:

                  https://www.ebay.com/itm/NEW-BMW-E30...-/253954109934


                  Make sure to post back once you get the part and go the install. It would be great to get more details on what is involved using the factory part.


                  MJ


                  A soldering gun is what is involved. You remove the pcbs from the plastic housings and swap the chips.

                  Comment


                    #10
                    Originally posted by gazellebeigem3 View Post



                    A soldering gun is what is involved. You remove the pcbs from the plastic housings and swap the chips.

                    Thanks for the clarification - I have ordered a stock E28 M5 coding plug and will get to work once it arrives.


                    MJ

                    Comment


                      #11
                      My coding plug (and cluster, coincidentally) arrived yesterday. I disassembled a 325i coding plug, right next to the E28 M5 unit - there is one glaring difference in coding plugs, and that is the length of the pins, on the E28 unit. The pins are not long enough to be installed into the E30 325i housing - they don't even protrude through the housing.

                      Unless there is something I am missing, the only way that I can see the unit functioning, is running the chip only, without the housing - which is not ideal.

                      Another question - since this is going into a late model car (two fuel sending units), will the fuel gauge read accurately? If not, what should I do about this? I don't want to swap in another fuel gauge, because they will either be unpainted, or the paint color will be different.
                      Autobahn Motorsport - Portland, Oregon
                      @autobahnmotorsport
                      '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

                      Comment


                        #12
                        So here what this looks like:
                        Click image for larger version

Name:	vo8wQnj.jpg
Views:	65
Size:	44.3 KB
ID:	9907291



                        I desoldered the chips, moved the M5 dude over, resoldered, reassembled and bob's your uncle. I did my SI batteries at the same time, which may be worth considering.

                        I have my head buried in the sand regarding the fuel tank capacity difference. The gauge will read an approximation of the fuel level. I'm sure there is a way to correct it but I haven't gotten there yet.

                        Comment


                          #13
                          Originally posted by gazellebeigem3 View Post
                          So here what this looks like:
                          Click image for larger version

Name:	vo8wQnj.jpg
Views:	65
Size:	44.3 KB
ID:	9907291



                          I desoldered the chips, moved the M5 dude over, resoldered, reassembled and bob's your uncle. I did my SI batteries at the same time, which may be worth considering.

                          I have my head buried in the sand regarding the fuel tank capacity difference. The gauge will read an approximation of the fuel level. I'm sure there is a way to correct it but I haven't gotten there yet.
                          Ah, that makes more sense. I appreciate the explanation. When my cluster arrived, I could tell it has been overhauled (face has been removed and polished, screw heads have minor marks, like it's been disassembled), so I will probably leave it alone.

                          For the fuel gauge, I was thinking about it in my sleep. Early model and M3 had only the passenger side sending unit - I wonder what would happen if one were to disconnect the driver side sending unit and jump the connector, so the only reading the gauge would be seeing, would be coming from the passenger side unit? Not quite ideal, but I don't know what else to do about it.
                          Autobahn Motorsport - Portland, Oregon
                          @autobahnmotorsport
                          '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

                          Comment


                            #14
                            Originally posted by e30austin View Post

                            Ah, that makes more sense. I appreciate the explanation. When my cluster arrived, I could tell it has been overhauled (face has been removed and polished, screw heads have minor marks, like it's been disassembled), so I will probably leave it alone.

                            For the fuel gauge, I was thinking about it in my sleep. Early model and M3 had only the passenger side sending unit - I wonder what would happen if one were to disconnect the driver side sending unit and jump the connector, so the only reading the gauge would be seeing, would be coming from the passenger side unit? Not quite ideal, but I don't know what else to do about it.
                            Bump for fuel level sensor issues. Going to try to tackle this job this weekend and would love to have a for sure plan.
                            Autobahn Motorsport - Portland, Oregon
                            @autobahnmotorsport
                            '88 M5 | '88 325is | '88 330is | '91 M-Technic 325ic | '00 M5 | '03 325it

                            Comment


                              #15
                              Disconnecting driver side doesn't work, it's a long loop and the dual sender systems have half the ohms. I went through this on the race car when eliminating fuel starvation in long sweepers. I added a 318 passenger side carrier to have an additional return in the carrier. When I hooked up the gauge it would read full at full and half at empty (makes sense). Ended up going back to a single internal pump, swirl pot and external pump to feed the engine.

                              So, since you are stuck with the early style single sender system due to the coding plug situation, you will need to do a little wiring. Since the system loops through both senders in a late model, you should be able to disconnect the driver side sender and ground it and/or loop it back to itself. AFAIK all the senders have the same ohms, and the reason they read half when swapping parts around is because the ohms are halved when wired in series. I am saying this without looking at the ETM's, but it's a simple solution.

                              john@m20guru.com
                              Links:
                              Transaction feedback: Here, here and here. Thanks :D

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