360 Bypass slow down light/cat temp ECU'S | FerrariChat

360 Bypass slow down light/cat temp ECU'S

Discussion in 'Technical Q&A' started by Motob, Apr 19, 2019.

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  1. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,238
    Frederick, Maryland
    Full Name:
    Brian Brown
    I recently installed an aftermarket twin turbo system on a a 360 Modena. The turbo system has no catalytic converters in the exhaust and no provisions for installing the thermocouples for the slow-down light system in the exhaust.
    The seller of the kit said to leave the thermocouples and slow down light ECU'S connected with the thermocouples just zip-tied in the engine compartment.

    The turbo kit seller reflashed the motronic ECUs with new software for the turbo system and elimination of the emissions control software to keep the check engine light from coming on. But they left the software for the slow-down light system intact.

    After a test drive the slow down light came on the dash display and both right and left motronic control units stored fault codes for catalytic converter temperature out of range. I know that the thermocouples are not getting too hot as they are reading the temperature in the engine compartment. I must surmise that the motronic control units are seeing the engine coolant reaching operating temperature, but the exhaust thermocouples are cold, so it sets faults because it thinks that the thermocouples are malfunctioning.

    Has anyone experienced this situation before?

    The only thing that I can do is to alter the signal from the slow-down light ECU's to one that the motronic control units will accept as a normal parameter for a warm engine.
    I have found these two threads regarding the fabrication of an emulator for the slow-down light system ecu:
    https://www.ferrarichat.com/forum/threads/thermocouples-slow-down-lights-related-cels-and-how-to-conquer-them.378429/
    https://www.ferrarichat.com/forum/threads/simple-2-7-slow-down-ecu-replacement-only-for-no-cats.538719/

    Has anyone done either of these modifications with success?

    I have also seen an Italian website with the same turbo system where they just installed a resistor in place of the thermocouple at the connector on the ECU: http://www.carserviceracing.it/le-nostre-auto/ferrari/ferrari-360-modena-f1-bi-turbo-606-cv.html Does anyone know if this is a viable option?

    Thanks!
    Brian
     
  2. Cribbj

    Cribbj Formula 3

    Brian I did some work with the Slow Down ECU's for the 550's and generated the plot of their output vs thermocouple temperature here: https://www.ferrarichat.com/forum/attachments/sdecu-20-custom-jpg.1566660/

    It's odd that in your situation, even with the thermocouples still connected to their ECU's, that the Motronics aren't happy. But perhaps the 360's Motronics are more sophisticated than the 550's. and as you surmised, maybe when the coolant temp is normal, the Motronics also want to see a "normal" temperature signal from the SD ECU's

    If you want to try and bypass the SD ECU's, for a test you could simply connect a 1.5v battery to that signal lead that goes from the SD ECU to the Motronic, and see if that cures the alarm. 1.5v simulates a thermocouple temp of between 750 & 850 degrees F. I believe FBB did this as a test a few years ago on his 550.
     
  3. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,238
    Frederick, Maryland
    Full Name:
    Brian Brown
    Thanks John, that's a great idea. I will do a simple test with a 1.5v battery before making any type of circuit that generates a comparable voltage.
     
  4. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    I know for sure that the 355 and the 360 use the same green TCU controller. I also know for sure that the 355 Motronic 5.2 sees the too cold thermal couple signal to be out of range which explains why tying off the thermal couple somewhere in the engine compartment will generate an error code. There are several persons that have invented a fake signal that fools the 355 ECU into thinking that the cat temperature is OK. I do not know if the 360 OBD2 system is more sophisticated than the 355 system when it comes to the TCU temperature probes. I do know that the 360 OBD2 system is more smart than the 355 OBD2 system when it comes to emission signals such as O2 sensors and the likes. It is not easy to fake out the O2 sensors on the 360, for example.

    Brian, I think you are in uncharted waters here.
     
  5. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    Ian Riddell
    #5 Qavion, Apr 20, 2019
    Last edited: Apr 20, 2019
  6. Franklin s cohen

    Feb 12, 2020
    5
    Atlanta
    Full Name:
    Franklin s cohen
    My Slow Down light is flashing in my 2004 360 Spyder. I'm assuming it's the sensors. Any ideas...parts look like about $370-$425...about labor costs to install?
     
  7. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    Might be a thermocouple or an ECU. If you're not fussy about fitting non-OEM parts, Technistrada offer cheaper units.

    https://technistrada.com/

    If it's the ECU, and you have some basic tools... metric socket set, screwdrivers, etc) it's an easy do-it-yourself fix. The ECU is found on a number of different Ferraris. Check out Ratarossa's YouTube videos on faultfinding.



    ECU location varies.

    If there is only one slow down light on your Ferrari type, an OBD 2 reader will pinpoint the faulty side.
     
  8. voicey

    voicey Formula 3

    Jul 29, 2009
    1,190
    London, UK
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    Aldous Voice
    Why don't you get the turbo vendor to program out the cat temp monitoring out of the motronics? We do it all the time.
     
  9. RacerWannabe

    RacerWannabe Rookie

    Jun 8, 2021
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    Jerry l Railsback
    You cannot use a simple resistor in place of a thermocouple to create a dummy signal. A thermocouple generates a mV potential based on a difference in temperature between the measured point and a reference point. A resistor simply resists current flow in a constant way. Additional theory for temperature measurement is beyond the scope of this thread. If you just want to kill the light you can buy a thermocouple simulator that plugs directly in at technstrada.com
     
  10. Qavion

    Qavion F1 World Champ
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    ... which is a resistor and diode in series. Now that I remember, Technistrada said that the dummy bypass was not suitable for the F360. The F360 engine ECU's do an additional check on the thermocouple ECU during startup. I can't remember if the dummy bypass in this case generates a light or just a hidden fault message on the F360.
     
  11. RacerWannabe

    RacerWannabe Rookie

    Jun 8, 2021
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    Jerry l Railsback
    I have no idea what is inside the technistrada simulator. If you want to avoid the CEL and the slow down light, you will need to dummy in a mV potential that represents a normal temperature. You will need a decent DMM, a resistor, a pot, and some electronics experience.
     
  12. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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