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quick MAF writeup (UPDATED, PICS - 1st POST)

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    quick MAF writeup (UPDATED, PICS - 1st POST)

    EDIT: Just in case anyone is wondering, I believe that the whole intake measures 3" in diameter. I put some random pics up of how the MAF connects to the intake boot in my project. Short explanations are in too.

    PICTURES: http://www.nauticaltech.com/~mike/in...?object_id=227

    the MAF conversion is pretty easy, so instead of trying to make some big writeup about it, i'll make it very clear and simple. This guide is meant for people who have a decent understanding of how the SMT6 works, and have attempted to tune their cars a little with it before using a MAF.

    - First, you need an SMT6. It needs to be wired into your ECU harness, and you must have control over the AFM signal. Also, use the AFM signal as your throttle signal. It also helps to have the O2 sensor hooked in for additional data.

    - Next, turn your car on and leave it idle. Turn on SMT6 logging and note what voltages your current AFM is putting out. Rev your engine up to 1K, allow a second for the SMT6 to log what your car is doing. Now, rev up to 2k for a second.

    - Now, drive your car around with logging still enabled. Attempt to subject your car to different loads/rpms. Make sure you do 1 WOT run to redline. Now, you should have a log of what your AFM is doing throughout the throttle/rpm map.

    - Next, get yourself a MAF and install it. I bought a 1998 328i Seimens MAF. As far as installation goes, all you really need to do is power the MAF, and get it's signal. You will most likely need a wiring diagram (http://www.autolib.diakom.ru:8001/CAR/BMW/). If you're using the '98 328i MAF, i believe pin2 is signal, pin3 is power, and pin1 is ground.

    - Crank your car up with the MAF installed. It will run and idle like absolute crap, so you must note right away what voltage the MAF is putting out. In my particular situation, my AFM put out about 1.33 volts at idle. The MAF put out about 0.9 volts at idle. All you need to do is create a MAP that will change the 0.9 volts to 1.33, and your car should idle fine (these are my numbers, your numbers may be different). In order to find the correct number to place into the map site, find the difference of the voltages (0.43 in my case), and then divide by 0.04. The result of that equation is about 11. Now, place the number 11 in the idle sites for your map. The reasoning for the .04 is because each point that you add onto a site will increase the line voltage by .04. So, if your MAF puts out .9 naturally, then you add 11points * .04, your MAF voltage will get bumped up to your car's "normal" operating voltage. In my case, due to slight idle fluctuations, there are 4 sites on the map that are used for idle, i placed a 11 in all 4 of them.

    - The hard part is done! Now that your engine should be idling normally, rev your car up to 1k, and note the voltage the MAF is putting out. Compare that with your log of the AFM, and compensate the voltage accordingly. In my case, i found that the MAF voltage increased somewhat linearly with the AFM voltage, so i ended up using numbers ranging from 11-15 throughout the entire map. Most will be using a wider range of numbers, or possibly even a lower range if you're lucky... if you're lucky to find a MAF that is closer to the stock AFM signal, let us all know!

    - Dont forget, now that you know how to create a map to work for your application, go and check your logs and find out what your car was doing @ WOT, then try to make the MAF do that as well. That's all there is to it... BUT, i suggest taking it slow (maybe 1k rpm) at a time. If you just try and do a WOT run with your SMT only calibrated to work up to 2k, then you might run too lean/rich.

    - You may want to install a temp sensor too, i'm not 100% sure what motronic does if it doesn't sense a temp signal, but i'm pretty sure it will lightup something on your dash. I cut the temp sensor out of an AFM and put it in the intake stream.

    I'm sure theres bound to be questions. I check this board a few times a day, and am usually on chat - so its easy to find me.

    aim - yoshi273
    yim - michael_spiegle
    msn - yoshi273@hotmail.com
    Michael Spiegle

    '01 Ford Escape / Daily Driver
    '99 M3 / Track Car
    '87 325is bronzit / wtf car
    '06 Daytona Triumph 675 / Daily Rider

    #2
    awesome write up!
    BEERTECH

    Comment


      #3
      :bow: is all I have to say.

      I have 98 328 Seimmens unit and 19lb injectors in my room.

      SMT6 this summer hopefully.This is so so so helpful.

      Comment


        #4
        where to buy the smt-6 from? did you guys buy it directly from perfect power?
        Thanks in advance
        '86 325

        Comment


          #5
          Originally posted by JPbmw
          where to buy the smt-6 from? did you guys buy it directly from perfect power?
          Thanks in advance
          Gunni, our friend from Iceland. He's the contact. (SN: Gstuning)

          and to answer your question from the other thread, last I heard it was like $340 shipped.

          Comment


            #6
            where are details about the SMT6?

            and what about Megasquirt? that looks better to me... but then again I don't know what features the smt6 has...

            i really like the megasquirt though... I think I'll wire the LEDs to a display and the MegaView to my dash somewhere... heh..

            Comment


              #7
              Originally posted by darien28
              where are details about the SMT6?

              and what about Megasquirt? that looks better to me... but then again I don't know what features the smt6 has...

              i really like the megasquirt though... I think I'll wire the LEDs to a display and the MegaView to my dash somewhere... heh..
              http://www.r3vlimited.com/phpBB2/viewtopic.php?t=1591 here's some more info about the MAF conversion, from mspiegle's early post. It includes a lot of discussion about the SMT6.

              Comment


                #8
                there's supposed to be a group buy on them at $250 each + shipping if we get 7 people or more. There's already 5 or 6 for sure, so email Trent (Apex engineering) if you're interested.

                Barry
                "I'd probably take the E30 M3 in this case just because I love that little car, and how tanky that inline 6 is." - thecj

                85 323i M TECH 1 S52 - ALPINEWEISS/SCHWARZE
                88 M3 - LACHSSILBER/SCHWARZE
                89 M3 - ALPINEWEISS II/M TECH CLOTH-ALCANTARA
                91 M TECHNIC CABRIO TURBO - MACAOBLAU/M TECH CLOTH-LEATHER

                Comment


                  #9
                  How big is the 328 MAF tat you used?
                  -Ted

                  Comment


                    #10
                    Did you power the MAF using 5v from the AFM wiring or did you use a 12v switched from the ignition? Just got a used m20 TB and it looks like it wont be too hard to put on a variable TPS. Ill inform the group when Im done.
                    I have an extra MAF from a 97 328i . Dont want to sel it yet since I want to test it. Got it from a member on BImmerforums from a 97 328iS, upgraded to a larger MAF. Should be in good condition otherwise.

                    Comment


                      #11
                      I want to say my MAF was 3"... but i didn't have a measuring tool availible. I believe I used the +12 volts from switched ignition.

                      $250/each is a killer deal, i suggest you guys get your SMT6 units while you still can.
                      Michael Spiegle

                      '01 Ford Escape / Daily Driver
                      '99 M3 / Track Car
                      '87 325is bronzit / wtf car
                      '06 Daytona Triumph 675 / Daily Rider

                      Comment


                        #12
                        Yes , and those in the group buy now, have more features then the original SMT6,

                        A possibility for a wideband sensor,
                        and also it has a 4th MAP wich can give out false O2 signals, saying goodbuy to check engine lights, and will allow tuning beyond what the motronic wants the O2 signal to be,,
                        Gunni
                        @ Prodrive / Aston Martin Racing

                        Comment


                          #13
                          Originally posted by reelizmpro
                          there's supposed to be a group buy on them at $250 each + shipping if we get 7 people or more. There's already 5 or 6 for sure, so email Trent (Apex engineering) if you're interested.

                          Barry
                          holy crap! 250? If only I had $$$ right now for that.

                          Comment


                            #14
                            it is a really good deal!! im in, does any one have the link to the thread for the group buy?

                            ps:gstunning you can count me in!
                            '86 325

                            Comment


                              #15
                              holy shit, i didn't know they were actually updated ones!!

                              contact TRENT (ApexEngineering) to get into the group buy
                              Michael Spiegle

                              '01 Ford Escape / Daily Driver
                              '99 M3 / Track Car
                              '87 325is bronzit / wtf car
                              '06 Daytona Triumph 675 / Daily Rider

                              Comment

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