Car dies when MAF is unplugged | FerrariChat

Car dies when MAF is unplugged

Discussion in '348/355' started by ThomasK, Apr 17, 2018.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    I thought the ECU was supposed to assume values using the TPS to keep the car running in case the MAF were to be unplugged or fail completely? my car just sputters and dies almost instantly when the MAF is unplugged.

    After my major i accidentily swapped the TPS with the knock sensor plug. i wonder if this is related. i am also having a crazy long term fuel trim issue in this thread, which may be related:
    https://www.ferrarichat.com/forum/threads/long-term-fuel-trim-whacked-out-with-graph.573850/

    ideas?
     
  2. salbrech

    salbrech Karting

    Dec 20, 2013
    103
    Hello ThomasK,

    I also found to have the TPS and the RHS knock sensor swapped when I bought the car. The engine was running perfectly, although it did throw CELs occasionally.
    Before and after I fixed that problem, I also disconnected the MAF with the engine on Idle, and as far I can remember, it never installed.
     
  3. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    thanks. im assuming the reason the engine is stalling is due to the problem im having with the long term fuel trims in bank 1. i was curious if these issues were related in any way.
    my car was surging at idle with those two swapped. afterwards it idled perfect. dont know if i had the LTFT issue while they were swapped though.
     
  4. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
    I wonder if one of the oxygen sensors in the exhaust is lying, to cause the fuel trim issue
     
  5. INTMD8

    INTMD8 F1 Veteran
    Owner

    Jun 10, 2007
    6,503
    Lake Villa IL
    I've seen o2's completely stuck at low mv or high mv skewing/driving trims but if it's actually functioning and switching (even if slow), not likely the issue.
     
  6. Davsk1

    Davsk1 Karting

    May 10, 2016
    155
    Lincolnshire UK
    Full Name:
    Dave
    Have they been checked? They are quite easy to check, and it's possible to bring them back to life by heating to cherry red with a blow torch
     
  7. ThomasK

    ThomasK Karting

    Dec 8, 2009
    132
    Houston, TX
    i did get it to run last night with the MAF unplugged. i was also monitoring my STFT's while it was unplugged. both o2's were reading positive STFT's (in the 20's at times) most of the time, indicating the ecu is compensating for a lean condition with the MAF unplugged.
    I should have logged the data, but i didnt.
    im surprised i was see such high STFT's so i ended up cleaning the MAF really well and ill try it all again tonight to see what happens. My o2 sensors are functioning properly, one of them is new, the other im just going to replace for the heck of it. and they are plugged into the correct upstream/downstream positions.
     
  8. INTMD8

    INTMD8 F1 Veteran
    Owner

    Jun 10, 2007
    6,503
    Lake Villa IL
    Not sure. I never mess around with old o2's, I just replace them.
     

Share This Page