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PID 04 LOAD value

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  • PID 04 LOAD value

    Hi all,

    I'm trying to understand what means this PID... Standard said that is a calculation of pourcentage of torque used currently by the engine

    I saw this PID equal to 15% for my gasoline car at idle which can be possible
    but I saw a 40% value for a diesel car at idle too

    If someone can help me to clarify this it would be great

  • #2
    The original equation works for gasoline motors: current airflow / peak airflow, at this rpm, adjusted for barometric pressure, expressed as 0-100%. The latest publication adds that second equation for diesel motors that aren't really based on airflow. In either case the value represents the engine's loading; the delivered torque versus the maximum available torque for the current conditions.

    I'm not sure if I can explain the 40% that you're seeing.


    • #3
      I think of it like this:

      Petrol load = [Airflow / Airflow [email protected] eng speed]
      Diesel load = [Torque / Torque [email protected] eng speed]

      The difference in notation is because diesels generally run unthrottled.
      40% at idle is normal for most passenger vehicle diesels in Europe (1.6 - 3litre say). At idle ~ 750 rpm you are required to make 40% of your available torque just to run ancilliaries etc... check your torque map and you will realise at this engine speed torque is low so 40% is still actually a low torque value.


      • #4

        Thanks for the answer... I guess i've understood, but yes it's wierd, actually PID 11 is more interresting to known the driver demand (what I looking for...)



        • #5
          Hi guys,

          I recently got a Citroen Saxo 1.1 for testing and it reads 5% calculated load value on idle when most vehicles do 12-20%.. Is sth wrong with that? THe car is running great.. And at WOT it reads 100%..

          The protocol is EOBD, how can I find out which specifically is, ie ISO, KWP etc?

          Is there any possibility that its load value is calculated differently than we know therefore it reads that low value?