Results 1 to 2 of 2

Thread: Questions about open/closed loop

  1. #1
    Advanced Tuner
    Join Date
    Dec 2014
    Posts
    592

    Questions about open/closed loop

    I'm trying to understand why my car goes into open loop and short-term fuel trims shoot up to 34% during certain scenerios. I mainly see this happen when coasting down a large hill - car will go into open loop and STFTs jump up to 34.4%.

    Is this normal? Is the car supposed to enter open loop when coasting down a large hill?

    Also, I have disabled DFCO - but I seem to remember this happening even before I disabled DFCO.

    Just trying to understand why it does this and what triggers it to enter open loop at times when coasting. I completely understand why a car enters open loop during heavy acceleration (PE mode), but not quite sure I understand why it enters open loop when coasting (sometimes).

    Thank you!

  2. #2
    Advanced Tuner
    Join Date
    Dec 2014
    Posts
    592
    Bump.... Just trying to understand the main reasons when/why a car goes into Open Loop to begin with and more importantly, if these +34.4% STFT "spikes" when coasting (usually down hills) are a major issue or not.

    Here is a log that shows the spike at frame 10014 (along with tune at the time the log was made and the scanner config file I'm currently using):

    082315-Spark_and_Shift_Changes-v1.27-ToGasStation.hpl
    2012Impala.cfg
    20150823_Spark_and_Shift_Changes-v1.27.hpt

    Feel free to make recommendations on tune changes as well!!! :-)

    Thank you!

    Edit - here is my stock tune too, just in case:

    2012Impala-Stock.hpt
    Last edited by jtrosky; 08-28-2015 at 06:41 AM.