Erratic idle on 348 | FerrariChat

Erratic idle on 348

Discussion in '348/355' started by Dave Monk, Aug 7, 2011.

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  1. Dave Monk

    Dave Monk Karting

    Apr 23, 2010
    213
    SW Virginia
    Full Name:
    David Monk
    #1 Dave Monk, Aug 7, 2011
    I have a question for the group: My 348 did some weird idle speeds last winter from time to time and the situation disappeared this spring and summer until this past week. Sometimes (but not always) the car will idle erratically when started. It will idle fast, then nearly choke out and then back up fast again. Sometimes when you pull out the car will barely move for a second or so. It seems when the car gets warmed up it runs fine and idles properly. Not sure if these cars have an idle control valve? I suspect it may be one of the throttle position sensors. There are no CELs.

    Any ideas?

    Thanks,

    Dave
     
  2. Miltonian

    Miltonian F1 Veteran

    Dec 11, 2002
    5,966
    Milton, Wash.
    Full Name:
    Jeff B.
    #2 Miltonian, Aug 8, 2011
    With symptoms as you describe, I would always first recommend doing a simple "re-initialization" of the Motronic ECU units, following the steps that have been posted here many times, particularly if the battery has been disconnected or discharged. It only takes a few minutes, it doesn't cost anything, and anyone can do it at home.
     
  3. Dave Monk

    Dave Monk Karting

    Apr 23, 2010
    213
    SW Virginia
    Full Name:
    David Monk
    #3 Dave Monk, Aug 8, 2011
    I assume that is the "disconnect the battery for 20 seconds, reconnect and idle the car for 15 minutes" reset procedure?
     
  4. 348steve

    348steve Karting

    Jul 18, 2018
    149
    Full Name:
    Stephen G
    #4 348steve, Sep 21, 2019
    I had the same erratic idle and stall issue. I had just completed a major major where i had the entire upper engine apart and literally took painstaking effort to put together the cleanest 348 you'll ever see. Every component was either new or diagnosed as perfect. No vacuum leaks as well.

    I had noticed once that by simply touching the secondary air intake tube assembly that the engine idle would change suddenly. But hell, that of course could not make sense since that system has nothing to do with idle vacuums in any way, its simply not in the loop.

    But today, after the problem became so bad that the car would stall at every corner I had to stare at it for a while and think. While staring at that stupid secondary tube I noticed a interesting thing .... the MAV cable is literally resting on the secondary tube. In other words when I was moving about the secondary tube I was also jiggling the MAV cable.

    So ... even though the MAV connector pins looked clean, I used some contact cleaner on them and re-connected diligently.

    The world change.
     
  5. Louis Brown

    Louis Brown Karting

    Dec 24, 2019
    83
    Richardson Texas
    Full Name:
    Louis Brown
    #5 Louis Brown, Sep 25, 2020
    What’s component is the MAV?
     

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