Jim Miller MAF issues?

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  • skat 325is
    Wrencher
    • Oct 2003
    • 296

    #1

    Jim Miller MAF issues?

    after being gone from the E30 world for about 15yrs i recently acquired a 89' 325ix with a Miller MAF III conversion installed along with a MSD 6AL and MSD coil. Car running pig rich, idles ok but when you drive you can feel the car has no power and sounds like its misfiring. Checked compression and all cylinders are within spec... 140 - 150psi across the board...so engine seems to be quite healthy. No vacuum leaks that i'm aware of (replaced intake elbow), disconnecting the MAF makes the rpms pick up a bit, like maybe from 750 to 850 - 900rpms. Anyways... question is, if i get an used AFM, can i run it with the Jim Miller chip installed on the ECU or i need to also get a stock chip / whole stock ECU as well ? I still need to double check a couple of things yet like if the wiring was actually done correctly or its faulty, if the actual Jim Miller chip is in the ECU, i peeked at the injectors and as far i remember...they don't look like the stock ones, so i need to investigate that too. Also exploring just ditching the whole motronic and go with the Classic Daily PnP ECU and lay down the pavement to the boosted plan in the future.

    Thanks in advance.​
  • 82eye
    E30 Mastermind
    • Jan 2009
    • 1850

    #2
    pretty sure the miller conversion requires the chip and the two work together. if the maf has gone both will need replaced. a few guys have tried to source the maf but it's really hit and miss. there's a common vw maf that corresponds to the part number but they don't seem to match when you have it in hand.

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    • AWDBOB
      R3V Elite
      • Aug 2013
      • 4370

      #3
      So on Jake's car, we searched for what seemed like forever trying to figure out why his m20 ran pig rich, before he did his stock to standalone video series. Come to find out, the car had a miller MAF on it in the past, and we found that the miller MAF setup requires 12v to be sent over the 5v AFM reference, so it was overdriving the crap out of the AFM.

      So you not only will need to switch to a stock ship, but also need to fix the wiring (typically done via their instructions a few inches up from the 51 pin DME connector).

      Miller MAF stuff is awful, and there is no support whatsoever. I would run stock stuff and upgrade to standalone when the time comes, but fully diagnose the car with stock ECU before converting to standalone.
      1989 Hooptie 325iS Build Thread
      1989 Zinnoberrot M3 Build Thread

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      • 82eye
        E30 Mastermind
        • Jan 2009
        • 1850

        #4
        Originally posted by AWDBOB
        Miller MAF stuff is awful, and there is no support whatsoever. I would run stock stuff and upgrade to standalone when the time comes, but fully diagnose the car with stock ECU before converting to standalone.
        to the best of my knowledge they closed up shop a while ago

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        • skat 325is
          Wrencher
          • Oct 2003
          • 296

          #5
          Thanks for the reply guys, i saw a picture online of the Miller MAF as a kit with injectors ?? I'm trying to look for it but cant find it again... did this also included injectors as part of a kit as well ?? As i mentioned when i looked under the intake manifold i saw injectors that didn't look stock, they look all black with no colored top portion. If so i'm guessing they're gonna be at least 19lb injectors which might also makes sense as of why its running rich.. I really didnt want to go the AFM + ECU just to get rid of this crap lol. I have an used AFM from ebay on the way, now need to score a cheap ECU *sigh*. As far as reverting the wiring back to stock it looks pretty straight forward and assuming they followed the instructions to the T.... its a matter of desoldering Pin12 joint with Pin37 and reconnecting it to ECU plug.

          I'll keep you updated on my findings.
          Thanks again.

          Comment

          • 82eye
            E30 Mastermind
            • Jan 2009
            • 1850

            #6
            Originally posted by skat 325is
            I have an used AFM from ebay on the way
            rock auto has refurbs that have worked for others if the used afm doesn't work out. i think they are sourced through blue streak electronics.


            Originally posted by skat 325is
            now need to score a cheap ECU
            just need to swap the chip in your existing ECU. they are available a few places.



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            • Andre3127
              Wrencher
              • Dec 2017
              • 291

              #7
              Send me message if you cannot find a stock chip. I can reflash a chip and mail it to you if you need.
              Budget E30 Parts - Used and Reconditioned parts for your BMW

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              • skat 325is
                Wrencher
                • Oct 2003
                • 296

                #8
                Originally posted by Andre3127
                Send me message if you cannot find a stock chip. I can reflash a chip and mail it to you if you need.
                PM sent

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                • skat 325is
                  Wrencher
                  • Oct 2003
                  • 296

                  #9
                  Im in talks with a guy that has a 173 ECU, so waiting on him for shipping price. AFM arrived today, thinking if i should source some injectors in case those are 19lb. I havent been able to do anything on the car, its too friggin hot outside and i'm a graveyard shifter so by the time i wake up its time to get ready to go back to work :(

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