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Hesitation at 3600 RPM what happens here? MS

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    #1

    Hesitation at 3600 RPM what happens here? MS

    I finally got the megasquirt up and running on my 88 turbo m20.. and going through the normal tuning process I have this hesitation at exactly 3600 RPM and 9psi every time I go through an acceleration run.. I have tried every mixture possible to no avail. it allways looses about 50 HP at that point for a second or so and then continues on its normal way at full power.
    Is there something else that is happening at this RPM that I am not accounting for? before the MS it did it occasionally, even naturally aspirated but only ever happend when it was raining(I think).
    Once I did the tuirbo and engine rebuild and tuning with a MAF, it went away. It is now back with the MS install. every other pressure and load at that rpm it doesn't hesitate but at that node on my Volumetric efficiency map it appears..
    Could this be a timing issue? it is not detonating.. and I know that TCD is running systems on stock timing.
    Any help would... matt are you having these porbs?
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    #2
    what you mean with hesistation? (sorry I don't get the phrase at all) measn like the engine has a kind of fall in the curve? I f so, I have something like that but not to pronunced, but is more like at 4800-5000RPM, I can feel it, but for sure my engine is not losing 50HP in that moment.

    Appart from feeling it, looks like the tach go a bit slow in that range, it doesn't go stright like when it was N.A..

    PS: What MAF are you using , I want to swapp for my 1993 E36 M50 MAF that has four pins, but I don't know what voltage value should I put there (i have the SMT6)
    Euro M3'87 NogaroSilver/Euro E34 M5 '93/Porsche 993 TT 97' Euro/Porsche 993 Carrera 95' Euro/Skyline R33 GT-R

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      #3
      Quite interesting,

      I have not had that problem while running MS but when It was no turbo 2.8l low compression (with stock engine management) It dipped down from 4500 to 5500. Is your VE table smooth around there? You might want to try riching or leaning it out to see if it makes a difference, to all of hte points around the node. Have you tried using a wideband o2 sensor? That could possibly tell you a lot. Thats interesting, you also might want to check the MS yahoo group, see if you can get any feedback there.
      Hope it works out for you!

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        #4
        Diego, hesitating = loss in power for a short term.. did you ever fix your problem? I am not using a MAF. MS uses a MAP sensor.

        Matt, are you using the afm still for timing? Todd at TCD suggested that it might control some of the timing. my dip in the power was a bit shorter and steeper than yours. what did you do to fix this problem?
        I am gonna switch to some cooler plugs and get rid of those crummy platinums. I tried to richen the mixture around that node to no avail..
        this is starting to get frustrating.
        -Pete

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          #5
          thanks for the explanation, well that's what happens with mine but just abit in that RPM range, I didn't fix it yet. :?
          Euro M3'87 NogaroSilver/Euro E34 M5 '93/Porsche 993 TT 97' Euro/Porsche 993 Carrera 95' Euro/Skyline R33 GT-R

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            #6
            Since that was my low hp reading, i added all of the turbo stuff, 32lb injectors, MS, no AFM and it was gone.

            What are you using for your stock throttle position switch? And you have the TPS for megasquirt as well correct? If you look at the gauges on MS, does it do anything when you hit that spot?

            matt

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