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Hall-powered M50... success!

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    Hall-powered M50... success!

    Those of you following along on my M54 OBD1 conversion probably know that I ran into a speed bump in that I can't mount a VR sensor in the front like everyone else can. I am forced to use the rear sensor wheel and stock Hall sender. I don't even have a front tooth wheel!

    All you M52/S52 OBD1 conversion guys haven't had it so bad, you have the wheel in the front and the VR mounting bung.

    Anyway, I developed the electronics to convert the digital Hall signal to something that the 413 computer can understand. It should have worked in theory and after driving it this afternoon I can say that it works in practice.

    That's right, I have replaced the crank position VR sensor on my M50 with a Hall sensor and it works. Drives awesome, actually. All the way to redline. Woot!

    Why should you care?

    If you have a working car without problems you probably shouldn't care much. However, if you have an M52/S52 conversion on the horizon this will let you retain the stock Hall sensor in the rear and not worry about getting the VR sensor for the front and the little plastic pieces.

    If you have a running M52/S52 you could ditch the front toothed wheel for the svelte M54 pulley.

    Ok, here's the cool part...

    I was able to "run" my motor without actually starting it.

    The Hall signal is easy to duplicate and by feeding a crank position signal and disconnecting my fuel pump relay, I was able to fire all the injectors and coils. The ECU thought the motor was running.

    Now, back to my M54...

    #2
    Cool stuff. Are you doing this with a PIC or some passive electronics? I'm curious :D
    cars beep boop

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      #3
      Originally posted by kronus View Post
      Cool stuff. Are you doing this with a PIC or some passive electronics? I'm curious :D
      Can't do this passively, no need for a PIC. I'm using a charge pump to generate negative voltages and an OpAmp as a comparator. Signal swings from -12v to +12v. Looks just like an A/C signal to the ECU.

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        #4
        Your my hero. Awesome thing you did, and I'm seriously blown away by your knowledge of the electronics. I barely can grasp my head around the idea let alone how the hell to implement it.

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          #5
          I'm impressed! Where there's a will, there's a way.

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            #6
            any technical benifits to a Hall-effect senser over a VR senser, other than location and ease of swapage?
            1989 cirrisblau-metallic 325i

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              #7
              Originally posted by SpecM View Post
              any technical benifits to a Hall-effect senser over a VR senser, other than location and ease of swapage?
              Hall sensors are generally regarded as superior somewhat because they are more immune to noise, but mostly because they are a true zero-speed sensor and will send a clean signal at very low rpm's. ie cranking.

              My thinking is that there will be slightly less jitter tooth to tooth because it's a digital signal. I have never felt that my VR sensor wasn't good enough so I'm interested to see what my day-to-day driving impressions will be now.

              I have mine wired with about 6 feet of Cat-5 computer cable, no shielding, no problem.

              Plus, I've already noticed that chics dig my car more.

              Comment


                #8
                Originally posted by hoveringuy View Post
                Plus, I've already noticed that chics dig my car more.
                :nice:

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                  #9
                  impressive!
                  I got a fender roller now! LMK if you need me to roll your fenders or want to rent the tool from me locally.

                  Paypal: vdang5@gmail.com

                  Delta Auto Care
                  2875-C Towerview Road
                  Herndon, VA
                  703.435.1375

                  My Feedback Thread: Evil_Twin

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                    #10
                    Originally posted by hoveringuy View Post
                    Plus, I've already noticed that chics dig my car more.
                    Sold!
                    1989 cirrisblau-metallic 325i

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