Long term Fuel Trim whacked out, with GRAPH | Page 3 | FerrariChat

Long term Fuel Trim whacked out, with GRAPH

Discussion in '348/355' started by ThomasK, Apr 15, 2018.

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  1. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    Here is the video showing how bank 1 moves with small throttle movements while bank 2 seems to have play. The joints are ok though it's a different part of the throttle body that is causing the excessive movement.
     
  2. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    And I would assume this would cause bank 1 to suck up most of the air...because it's opening more at all throttle positions.
     
  3. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    Here is another video using my boroscope to see the play on bank2 throttle linkage. Bank1 doesn't have this play
     
  4. INRange

    INRange F1 World Champ
    Silver Subscribed

    Jan 27, 2014
    10,009
    Virginia/Florida/Caymans
    Full Name:
    JD
    I believe you found the most likely cause of the fuel trim issue. It also fits because it was disassembled as part of your major.
     
  5. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    i logged more data at idle and low, no load rpm. I also adjusted the sync screw on bank 2, #4 in the pic until i could visually see the linkage open along with bank1 instead of behind it. if you remember my other graphs in the thread, the STFT would go lean in bank 1 and rich in bank 2. Now it seems a little more balanced with bank 1 going rich while bank2 goes a little leaner. I think im moving in the right direction and knowing that this is affecting my data, i should just get them balanced with the SD1 at the dealer.
    It still isnt fixing my LTFFT though. bank 1 is still stuck at 22.66%. maybe it just needs driven
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  6. INTMD8

    INTMD8 F1 Veteran
    Owner

    Jun 10, 2007
    6,487
    Lake Villa IL
    If your short terms are now inverse of the long terms they should all zero out given enough time to re-learn.
     
  7. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    thats what im hoping! i need to take it for a spin and see if they ever correct. wish i could just reset them manually but probably need SD1 for that.
     
  8. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
  9. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    did a compression test last night. 197 and 214 were the outliers, but all others were 203. So it isnt a compression issue.
    im getting the fuel parts to test fuel pressure tonight.
    i dont think the throttle body alignment is the whole issue, i think its part of it, but not all.
     
  10. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,292
    socal
    I did not read the whole thread. If this was an OBD2 car I would use a phone based obd reader.
    All other OBD readings should make sense
    I would prove my way to resetting and manipulating LTFT
    Throttle linkage was mentioned...no leaks from there confirmed? starter spray trick
    My 1st guess, based on glancing through this thread, would be Injectors and or cats since leaks seem to be ruled out.
     
  11. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    thanks. i do want to get a 2nd opinion on whether or not the values im seeing in my LTFT are bogus. whether it be a phone reader or just getting it hooked up to an SD1. i injected compressed air at about 10psi into my plenums last night and couldnt feel anything leaking from anywhere around the plenums or TB's. Im going to be checking fuel pressure within the next few days to see if it is low.
    i did notice that my STFT on the downstream o2's were pegged at 99%. the o2's are all new bosch units 13819 F and 13820 rear and are hooked up correctly. I did find that there was a 13820 in the upstream location on bank 2. i bought the car that way i guess, i changed it to a 13819. im trying to drive it around to see how the LTFT values change and adapt, it went down 1% to 21.3% last night.
    next check is fuel pressure.
    downstream o2 shouldnt affect fuel trims, at least they dont on all other cars ive dealt with.
     
  12. johnk...

    johnk... F1 World Champ
    Owner

    Jun 11, 2004
    10,628
    CT
    Full Name:
    John Kreskovsky

    Why does this myth go on and on and on.... From the WSM

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  13. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    i saw that in the WSM also, but it says in case of front oxygen sensor aging. that means to me if the voltage waveform is slower than normal switching frequency or flatlines on the upstream o2 then maybe the downstream does something. i have new o2 sensors all around, so those downstream o2's shouldnt be contributing anything to fuel trim. but its hard to tell what ferrari meant by "oxygen sensor aging".
     
  14. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    does anyone monitor their fuel trims that could see if their downstream o2 fuel trims are 99%?
     
  15. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    my guess is that 99.2% is a default value when the ecu doesnt communicate that value to the software. i am ignoring it since it is on both banks and not just 1, i am thinking it is bogus.
    i am using OBDwiz, fyi.
     
  16. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    I drove it to work today after making a small adjustment to the sync screw again last night.
    Now my ltft is closing the gap a bit which is nice. Bank 1 down to 15 and bank 2 is up to 9. Now I know i still have the ecu adding fuel so I'm going to check fuel pressure this weekend and maybe just get a new maf because it's cheap.
    Progress!
     

    Attached Files:

  17. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    ok, so did more testing. hooked up a fuel pressure gauge to the schrader valve on the outlet of the fuel filter. i read a steady 56psi at idle. However, when i shut the car off i noticed the gauge pressure dropped rather quickly and was zero within 5 minutes. ok, so now i know there is a pressure loss somwhere, but where. Well i ended up plugging off the return lines from each bank so i can see if its the regulator(s) dropping off the pressure. I primed the pump and the gauge went to 60psi and held there.
    So...i assume that either bank 1, 2 or both fuel regulators are leaking internally to the return line. So im going to try new regulators and see what my new trims will be afterwards.
    i would love to convert to aeromotive units just need the right fittings off the fuel rails. anyone done this?
     
  18. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    5,942
    Indio Ca/ Alberta
    Full Name:
    Grant
    I think he is going from closed loop to open like you said james.
     
  19. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    5,942
    Indio Ca/ Alberta
    Full Name:
    Grant
    I thinka helicopter guy did but cannit remember his name.
     
  20. SoCal1

    SoCal1 F1 Veteran
    Owner

    Jun 14, 2011
    8,562
    SoCal LA/OC/New Mexico
    Full Name:
    Tim Dee
    Just to throw a wrench into your thoughts
    The 2.7 motronic has 3-4 maps the 5.2 has around 15 or so that are divided up which way to tuesday as to what one takes over under what conditions. With the bypass closed it runs a bunch of economy low emission maps that cause havoc if everything is not perfect, open bypass is way more forgiving unless the 02's are not seeing what they want or the ecu just dont feel like getting out of bed that day.
    I been over these ecu's like a fat kid at a buffet. Total junk 1st gen electronics.

    :)
     
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  21. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    id be interested in more details about the ecu, i could PM you sometime. i thought i would post an update. I did end up replacing my MAF because i got a new bosch "open box" one off amazon for $50.
    after a few more hundred miles these are my new LTFTs. i did notice this MAF reads about 10% more airflow than the old one did...at idle at least. i think replacing the MAF along with finishing up syncing the left to right banks will get me there. I am waiting to use my custom made 8 port manometer for getting the TB's perfect.
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  22. SoCal1

    SoCal1 F1 Veteran
    Owner

    Jun 14, 2011
    8,562
    SoCal LA/OC/New Mexico
    Full Name:
    Tim Dee
    I posted some of the internals, I'll add more as time permits
    I'm taping out on Ferrari ecu's for now, need to get back to other projects :)

    https://www.ferrarichat.com/forum/threads/355-5-2-ecu-map-table-locations.580498/

    https://www.ferrarichat.com/forum/threads/348-2-7-ecu-maps-tables.580497/

    xo
     
  23. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    thanks. have you explored implementing a motec M800? ive queried a company in AUS that have used them before with success. My plan would be to use a completely new harness and be able to delete some factory systems, be able to have full accessibility to tune, etc. I come from the tuner world so trying to apply to this 355 would be nice.
     
  24. SoCal1

    SoCal1 F1 Veteran
    Owner

    Jun 14, 2011
    8,562
    SoCal LA/OC/New Mexico
    Full Name:
    Tim Dee
    All the aftermarket are very close, I'll use whatever they give me to try out. I usually make all my own parts.
    I have other non ferrari projects, life evolves and you move on. I find ferrari obnoxious and boring, no offense to anyone it just bores me to do the same thing more then once :)
     

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