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MAF System

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  • #31
    Originally posted by LeeVuong View Post
    As there been any new developments with Miller's kit for S14? Has anyone seen yet a graph with AFR or something of similar info? Who has one in their car, apart for Eric Gilles? BTW What octane were you running when you got pinging at mid RPM? 91 or 94?
    I was always running 93 octane-usually BP/Amoco, but I tried Shell and Chevron for good measure but with no difference.
    Eric Giles
    '07 X5 4.8i
    '01 325i


    • #32
      It's been a while since I had anything to report, so here goes. A few months ago I was e-mailing the guys at Miller again about what to do next to try to resolve my pinging under load. They were very helpful with suggestions, but in the end it was going to require me purchasing more equipment for testing and tuning. In my area any type of dyno or tuning shops are non-existent, so it is left up to me to figure things out.

      In the end, since the Miller system was advertised to be plug and play with no tuning required, the fact I was going to have to invest more time and money to fix the issue just wasn't what I wanted to get into. So this evening, I removed the Miller MAF kit and went back to the trusty AFM.

      Before I reinstalled the AFM, I removed the top cover and inspected the carbon tracks where the wiper arms touch. They were a bit grooved, so I carefully bent the arms down so that they would contact a new area of the carbon tracks. It really seems that made a noticeable difference! Off idle throttle response is better than I remember it being previously with the AFM.

      I now have no more pinging, and no more black smoke under full throttle that I had with the Miller MAF. I will have to monitor to see if my MPG improves, as it seemed to suffer after having the Miller for a while. I know I lost a bit of torque and the driveability benefits of the Miller system, but overall I am happier with the tried and true AFM with my iigomotiv chip-the car is running very nicely again with no issues.

      Brody and the guys at Miller were very nice and responsive to my requests for help, and I wish them the best-but my car just did not respond well to the Miller kit as delivered.
      Eric Giles
      '07 X5 4.8i
      '01 325i


      • #33
        Originally posted by marques View Post
        When I looked into this (chip-only MAF solution) back in the days before it was banned in Prepared class in Club Racing, what I found was that the transfer functions of the MAF and the AFM were so different (one is more logarithmic, the other is more square-root), that there simply isn't enough adjustment range in the factory correction tables to fix it properly.

        IMHO, you need either some signal conditioning between the MAF and the ECU (piggyback system like the Split Second), or you need to re-write the code and change the routines so you can use the different shape transfer function of the MAF.

        I went as far as re-doing the code to work with any arbritrary transfer function, but just when we were about to start testing, MAF conversions were banned in Club Racing and that's as far as I got. The project has been mothballed ever since, but could be resurected if there is enough interest.


        Without any negative criticism towards the Miller system.
        I take your observation to possibly mean that this could possibly account for the inconsistency in fuel mixtures as reported by the users of this product?

        I appreciate that Miller would take the time and expense to produce an economical system for a very small customer base, but our engines are expensive to replace.

        Last edited by Mmark; 09-10-2007, 03:27 AM.


        • #34
          With the disclaimer that I don't have any experience with the Miller system, never seen one, nor do I have any idea what was done in the code, all I can say is that it would be difficult to tune the system properly over all load conditions just by playing with the stock fuel curves (which only have a 0-200% adjustment range). And the logarithmic nature of the AFM is embedded so deeply in the code that it's not exactly a trivial effort to get it to work with a MAF.



          • #35
            And the thread lives on...just posted on the SIG that I'm in the process of installing my Miller MAF kit with the piggyback unit. I will be spending a bit of time on the dyno for tuning and then will respond with initial feedback on setup and driveability. I never considered using a 'plug and play' version of this without the piggyback unit. My engine is a 2.5 with EVOIII cam specs. Stay tuned (pun intended)...

            - Jeff


            • #36
              Just to clarify a few things... Split Second is still actively selling the MAF conversion for the E30 M3. People have been getting great results with the Split Second system for 10 years. Over the last several years, most people have chosen the laptop programmable kit.

              MAF conversion is allowed in BMWCCA club Racing in the D mod class. The Bullet Performance/Split Second car won the DM class national championship in 2007. That win was against all cars in the DM class including newer E36 and E46 cars some with stand-alone ECUs.

              If you would like to see dyno results you can go to and click on Project Cars. The E30 M3 entry is for a street car and shows dyno results. The E30 M3 DM Race car shows the 2007 DM winner and dyno results with both the MAF 4.0 and MAF 4.75 sensors. There are also more photos in the Racing section.

              The transfer function change going from an AFM to MAF sensor is important, but not the only thing you have to worry about. The Split Second conversion also addresses the transient response issue as well as elevation compensation. These things are very important in real-world situations.
              Mark Amarandos
              89 M3 w/MAF 4.0
              90 M3 DM w/MAF 4.50
              07 335i w/Turbo Tuner


              • #37
                Bringing back an old thread...

                Mark, et al..

                I am very interested in the Split Second MAF conversion but wanted to understand more about the system. Specifically once the system is properly tuned are any further adjustemnts required for different altitudes or different seasons of the year? Also did you install the Intake Air Temperature sensor? My car is daily driven.

                Thanks in advance,