Check Engine/Slow Down lights on a 512 (M) | FerrariChat

Check Engine/Slow Down lights on a 512 (M)

Discussion in 'Boxers/TR/M' started by ag512bbi, Oct 25, 2018.

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  1. ag512bbi

    ag512bbi F1 Veteran
    Owner Silver Subscribed

    Nov 8, 2003
    7,540
    So. Cal
    Full Name:
    Armen
    To start, My M has Tubi exhaust with no Cats.
    The Check engine & Slow down lights flicker OFTEN. At first i figured it may be a reaction due to the O2 sensors getting read improperly, But every once in a while I feel a lack of power.
    Please understand, I don't know too much mechanical. Anyone else have these issues? What should I be looking for?
    Some helpful advice will be appreciated.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Can you be more specific? Do you have:

    1. precats present, no regular cats, and Tubi muffler

    or

    2. no precats, no regular cats, and Tubi muffler

    I'm guessing that you have #1, as it's physically impossible to overheat the exhaust thermocouple(s) with #2, but it also sounds like (if you have #1) that you are loosing a bank of ignition occasionally. When you have the loss of power, does one of the slow down lights stay "on"?
     
  3. ag512bbi

    ag512bbi F1 Veteran
    Owner Silver Subscribed

    Nov 8, 2003
    7,540
    So. Cal
    Full Name:
    Armen
    Ill have to go to my warehouse and see. The light never stay on for more than a few seconds straight.
    Is it possible one side briefly shuts down due to the computer being confused, not knowing there are no cats and thinking its overheating?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,035
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    Because no one ever actually stopped when the slow down light came "on", the Motronic system shuts down fuel to the bank if the slow down ECU reports that the thermocouple is detecting overheating -- so if the slowdown light comes "on", losing power is sort of an intended result. However, the order of events in real overheat situation would be more like: 1. losing power (because a bank of ignition failed), then 2. the slowdown light comes "on" -- so the order of events is important. The slowdown warning light ECUs are notoriously flaky, and, if it wrongly turns on the light when the thermocouple isn't actually overheating, you still lose power. If the slowdown light just comes "on" instantly that could be a sign that the slowdown light ECU is flaky as it should first flash for a while and the go "on" solid -- see Section C in your OM. Additionally, if the "self-test" doesn't always work correctly (the slowdown light should come "on" for ~ 2 seconds when you first turn the key to Pos II and then go out) = a sign that the slowdown ECU is bad. If the slowdown light just stays "on" during the self-test, it's an obvious failure, but if the slowdown light doesn't come "on" during the self-test, it doesn't look bad, but is still strong evidence that the slowdown ECU for that bank is flaky. You can always swap slowdown warning light ECUs if it always the same bank that misbehaves to determine if the slowdown ECU is flaky or if that bank is maybe really overheating.
     
    AClark likes this.
  5. ag512bbi

    ag512bbi F1 Veteran
    Owner Silver Subscribed

    Nov 8, 2003
    7,540
    So. Cal
    Full Name:
    Armen
    I appreciate your input and give it a shot.
    Thank you.
     

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