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AFM Sensor Question

Discussion in '3sge' started by CO86GTS, Oct 8, 2012.

  1. CO86GTS

    CO86GTS Member

    Hi All,

    I just picked up an 86 GTS not too long ago and am in the process of rebuilding the engine and am planning on tuning for E85 when everythings done. A quick question I have is on the stock AFM sensor. I see conflicting information around the internet. Some say its a voltage metering flap and others say its signal output is a resistance value. Can any of the experts tell me which one it is? I'm trying to decide on which piggyback ECU to go with as some can tune both voltage and resistance flaps and others can only do voltage.

    Thanks for your help!
  2. ST165-2765

    ST165-2765 Well-Known Member Donated!


  3. Klue

    Klue Well-Known Member Donated!

    it produces a resistance as the potentiometer implies. The problem is not how it works, but how the ecu uses it. The AFM is used to determine engine airflow and thus load. Changing the signal from this to adjust fueling is not a good idea, as it does more than just adjust fueling. The ECU uses the AFM to determine how much timing the engine requires for its given airflow. If you are planing to run E85 its a far better idea to get a stand alone system with the proper sensors to accomidate your fuel choice. As well as prepping your fuel system for the fuel change. E85 requires almost twice the fuel for a stoich ratio, it also requires your fuel system to be purged of any varnish or build up from using regular gasoline. Or it will just end up clogging your filter, and possibly injectors

    Sounds like a cool project

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