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slow down lights/5-8 bank

Discussion in '348/355' started by veryfast355, Sep 14, 2011.

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  1. veryfast355

    veryfast355 Karting

    Sep 24, 2007
    120
    gt neck long island
    Full Name:
    michael c
    #1 veryfast355, Sep 14, 2011
    I have had a very irritating problem with my low mileage 95 ,355. I have under 10,000 miles and upto now have had no problems of any type. Recently the slow down light/ has been erratically coming on and then shutting down the the left bank.I took it to my mechanic and he said there were hair-line cracks in ECU's so he replaced both of them.Then i took the car back and it was fine for a couple of miles until the same problem again! He came to my house and we went for a drive and eventually after 3 or 4 miles it did it again.As he was in the car he opened up the fusebox/relay in the passenger footwell and jiggled the box and the lights went off. So he took the car back to his shop and went through every solder joint to check for any breaks or loose connections-- to no avail.He has had the car for several days ,taken it out for runs and the problem has not returned.He is still concerned that he has not really solved the problem but as he cannot get the problem to occur again he is now returning the car back to me.Is he missing anything?
     
  2. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
    Full Name:
    Tim Keseluk
    #2 2NA, Sep 14, 2011
    Sounds like an intermittent problem. If he was successful at restoring the connections it might not be back (soon).

    You'll know soon enough.
     
  3. plugzit

    plugzit F1 Veteran
    Silver Subscribed

    Dec 1, 2004
    7,773
    Redondo Beach, CA
    Full Name:
    Bruce Bogart
    #3 plugzit, Sep 14, 2011
    I hate intermittent problems since they are the hardest to diagnose. Sometimes I just wait til they become constant, as long as oil pressure, temperature, and perfromance are ok, then they are easier to diagnose.
     
  4. 355rockit

    355rockit Formula Junior

    Dec 1, 2010
    892
    San Marcos, CA
    Full Name:
    Vas
    #4 355rockit, Sep 14, 2011
    I was getting the 5-8 CEL on every drive when I first got my '95 F355. After changing out the O2 sensor, it was much less ferquent. Cleaning the MAF connectors reduced this even more. Recently I cleaned all (easily accessible) engine sensor electrical connections and she seems much happier.
     
  5. DaveK

    DaveK Rookie

    Jul 6, 2006
    18
    #5 DaveK, Sep 14, 2011
    At least on 348s, I've seen plenty of threads saying that the cause of the slowdown lights is often a faulty cat thermocouple rather than the ECUs (although they fail plenty too). Is it possible that's the problem? Maybe swap them over and see if it switches to banks 1-4.
     
  6. veryfast355

    veryfast355 Karting

    Sep 24, 2007
    120
    gt neck long island
    Full Name:
    michael c
    #6 veryfast355, Sep 14, 2011
    davek.... sorry that was my error... i meant to say the cat thermos.... so he changed those for new ones.
     
  7. DaveK

    DaveK Rookie

    Jul 6, 2006
    18
    #7 DaveK, Sep 14, 2011
    OK - in that case, what about the ECUs? If you swap them, does the light switch banks? Or has he replaced the thermo's and the ECUs?
     
  8. veryfast355

    veryfast355 Karting

    Sep 24, 2007
    120
    gt neck long island
    Full Name:
    michael c
    #8 veryfast355, Sep 14, 2011
    he swapped the ECU's over and he was never able to get the lights to appear;thats why he is so frustrated because the only time it happened when he was in the car was when he came to my house and we drove it for several miles.It only happened at the end of that drive and it was the only time he actually saw it with his own eyes. it was then that he jiggled with the fuse box etc and as he jiggled the lights went off and on, which made him believe that the problem was there and not at the engine end of the car.
     
  9. FBI

    FBI Formula Junior

    May 27, 2008
    446
    Calgary,Ab
    #9 FBI, Sep 15, 2011
    Did you check your coil packs? I just had this problem on my 348 and it solved it along with an alternator rebuild. Hope this helps.

    Cheer's
     

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