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m20 mid-range hesitation

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    m20 mid-range hesitation

    ok guys so here are the symptoms:

    car revs freely to redline when in neutral
    car revs freely to redline with %0-%75 throttle
    car revs terribly from 2900-4200ish rpms at >75% throttle.

    so basically under heavy load, hesitation at mid-range rpms.
    i did as much research as a i could and found some information, but nothing that perfectly fits my situation. i can start replacing everything under the sun, but am looking for suggestions on what to check/replace first.


    AIR:
    already checked for vacuum leaks, nothing seems to be amiss. checked afm for free movement, checked out fine. going to also try one that is a known working one.

    SPARK:
    can this possibly be something with spark? cap and rotor aren't very new. wires are relatively new in their lifetime. going to try a different known working ECU, but the ECU is not that old (was replaced once already)

    FUEL:
    i really can test the flow of the injectors with the tools i own. could a dying pump cause this? or perhaps a clogged fuel filter?

    any input is greatly appreciated.

    #2
    I've heard of DMEs doing this

    does it happen intermittently, or every time?
    1989 cirrisblau-metallic 325i

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      #3
      Originally posted by SpecM View Post
      I've heard of DMEs doing this

      does it happen intermittently, or every time?
      everytime since it started happening, and started means one day it wasnt, the next there was hesitation. it wasnt like i was getting a little hesitation at first and it got worse. off/on.

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        #4
        This could be caused by a bad AFM.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

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          #5
          i didn't think that the afm was used for measure at WOT? i think that the fuel filter is a fair guess for the first check. WOT is the highest fuel output time and when a clogged filter is mostly to show up
          bring it http://athomasmr23.mybrute.com

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