355: can LTFT be reset? | FerrariChat
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355: can LTFT be reset?

Discussion in '348/355' started by Carmellini, Mar 1, 2021.

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  1. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    953
    #1 Carmellini, Mar 1, 2021
    I just fixed a number of intake leaks and wonder if it is possible to reset my stored LTFT data? Would like to start from scratch to determine new readings? I know disconnecting battery will not do it, and not able thru scanner tool.
     
  2. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    6,016
    Indio Ca/ Alberta
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    Grant
    #2 taz355, Mar 1, 2021
    Yes but I don’t know how long it takes
    Years ago when I used to shut the power off via the disconnect switch, my ltft would reset.
    I believe this is why you need to let the car idle for a while when starting it again.

    you could try over night as that should work. Don’t think anyone has asked this in years so post how it goes.
     
    emac likes this.
  3. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    Ian Riddell
    #3 Qavion, Mar 2, 2021
    Carmellini has a 5.2 car. There is still some debate over what happens to faults and fuel trims with a battery reset.
     
  4. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    953
    #4 Carmellini, Mar 2, 2021
    Does not appear that you can reset fuel trim; maybe with SD@? info is stored in KAM, but don't understand how that works...there must be an internal battery in the Motronics ECU? Here is a link for fuel trim reset on a 360:

    https://aldousvoice.com/2013/01/16/ferrari-360-ecu-reset/

    Guess I will just need to drive a bit for parameters to change; was a bit unsettling to see the same numbers after hours of work....lol
     
  5. m.stojanovic

    m.stojanovic F1 Rookie
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    Dec 22, 2011
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    Miroljub Stojanovic
    #5 m.stojanovic, Mar 2, 2021
    There is no need for a battery, the info could be stored in an EEPROM chip.
     
  6. Qavion

    Qavion F1 World Champ
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    #6 Qavion, Mar 2, 2021
    Last edited: Mar 2, 2021
    No internal batteries. EEPROMs

    https://en.wikipedia.org/wiki/EEPROM

    Electrical charges are stored on chips. A bit like capacitors, but keep their charge indefinitely (or at least for a long time).

    (EDIT: Miro beat me by 10 milliseconds)
     
  7. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    953
    #7 Carmellini, Mar 2, 2021
    LOL

    would the trim be reset by number of drive cycles, or length of time?
     
  8. johnk...

    johnk... F1 World Champ
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    Jun 11, 2004
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    John Kreskovsky
    #8 johnk..., Mar 2, 2021
    LTFT is constantly being adjusted. So if you did something that would effect fuel trim you should see LTFT change pretty quickly. LT doesn't really mean Looooog term between adjustments. It means that the adjustment should be stable over a longer term. STFT change with throttle and load application. But if you make a repair to a component like a O2 sensor or MAF that was not operating correctly, or a misfire, thus pushing LTFT high or low, LTFT should response to the repair over a short drive.
     
    Qavion likes this.
  9. Beetle

    Beetle Formula Junior

    Apr 10, 2013
    776
    #9 Beetle, Mar 3, 2021
    No this cannot be reset from my investigation that I have undertaken. It changes pending the parameters sent to the ecu from the sensors. If there is a fault it will CEL. If you clear the fault it will come back until you fix the problem then read within +/-10% or you will get another CEL. A bottle of injector cleaner cleaned my trims up a little. Well and truely within spec now
     

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