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SLOW DOWN LIGHT FLASHING FOR A WHILE THEN NOT

Discussion in '348/355' started by curtis13, Oct 29, 2010.

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  1. curtis13

    curtis13 Rookie

    Sep 20, 2010
    35
    Destin fl
    Full Name:
    Curtis
    #1 curtis13, Oct 29, 2010
    ok guys. sorry for the stupid posts. i have read all the posts about this problem and cant get right.

    i replaced one of my cat ecu's to fix this and i cycled the battery and drove it through two heat cycles. the light went away and then about 10 minutes later it came back flashing in my face...... oooooo lovley.......

    it could be that i didnt reset the car correctly, i turned the battery off for about 30 minutes.

    my question is why in the world would it go away and then come back. i have tested both cats and they are not anywhere near overheating and this was city driving i was just cruising around town.

    i have my bypass valve wired open becuase it doesnt work for some reason.

    any help, again.......

    thanks guys
    curtis
    850-259-7223
     
  2. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,566
    San Carlos, CA
    Full Name:
    Mitchell Le
    #2 yelcab, Oct 29, 2010
    If you are absolutely sure that the cats are not overheating, and the ECU is fine, then the only thing left if the actual thermocouple needs to be replaced.
     
  3. GerryD

    GerryD Formula 3

    May 5, 2010
    2,442
    North of TO
    Full Name:
    Guido
    #3 GerryD, Oct 29, 2010
    make sure your engine oil is not overfilled/
     
  4. 285ferrari

    285ferrari Two Time F1 World Champ
    Sponsor

    Sep 11, 2004
    20,958
    MD and NE
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    Robbie
    #4 285ferrari, Oct 30, 2010
    There are 3 cat ecu's---you test all of them?
     
  5. 355 Shwing

    355 Shwing Karting

    Sep 9, 2009
    157
    Gulf Breeze, Fl
    Full Name:
    Craig Payette
    #5 355 Shwing, Oct 31, 2010
    I'm running test pipes, and I disconnected the damn things all together. If you're running test pipes, you don't need them. Even if you aren't running test pipes, you still "probably" don't need them. Ask Ernie about this. Those ECU's never worked the way they are supposed to.
     
  6. curtis13

    curtis13 Rookie

    Sep 20, 2010
    35
    Destin fl
    Full Name:
    Curtis
    #6 curtis13, Nov 12, 2010
    i still have the stock cats.... they dont rattle and i also have a temp gun and they are not overheating at all. i am thinking about pulling the bulb. love my car but damn the exhaust!!!!!!!!!
     
  7. WATSON

    WATSON Two Time F1 World Champ
    Owner Rossa Subscribed

    Sep 9, 2010
    23,686
    WI
    #7 WATSON, Nov 13, 2010
    Wish I could help, but I am too new to this and still learning.

    For my education, what temp is "overheating"?
     
  8. ronrob

    ronrob Formula Junior

    Jan 15, 2007
    395
    Var, S.E. France
    Full Name:
    Ronald Brown
    #8 ronrob, Nov 13, 2010
    I suggest that you address 285ferrari's question (fourth post). The fact that the light went out for a short time does not necessarily mean that all ecu's are in good shape. Have you tried the usual trick of fitting the good (new) ecu to each ecu site successively and firing up for a reset each time?
     
  9. windsock

    windsock Formula 3
    Rossa Subscribed

    Nov 29, 2006
    1,153
    #9 windsock, Nov 13, 2010
    2.7 or 5.2? Wiring open the bypass valve can create false warnings on a 5.2. Also ensure that the thermacouplers on the RH side go to the correct location on a 5.2. If they get crossed it will cause false warnings as well. There are alot of ECU failures and connector problems with the catalyst monitor system. If you have only one catalyst functioning on a 5.2 it will cause false warnings as it has a plausabilty program to compare temperatures from side to side.
    This should get you started, good luck.
     
  10. curtis13

    curtis13 Rookie

    Sep 20, 2010
    35
    Destin fl
    Full Name:
    Curtis
    #10 curtis13, Nov 13, 2010
    its a 99 5.2 i have ordered one new ecu for the exhaust and i tried swapping it to all the 3 positions with no avail. my bypass is wired open

    i have not tried switching the probes on the right side. thats a good idea.

    thanks for the info.... shes getting a good waxing tomorrow and i will do that change then

    i will post tomorrow in the pm

    thanks
    curtis 850-259-7223
     

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