F355 instrument change | FerrariChat
Buy

F355 instrument change

Discussion in '348/355' started by F355Bob, Nov 13, 2007.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. F355Bob

    F355Bob Formula 3

    Nov 4, 2003
    2,001
    Madison, Wisconsin
    #1 F355Bob, Nov 13, 2007
    Last edited by a moderator: Sep 7, 2017
    I did this last winter. They are Stewart Warner gauges and the speedo is one that you can calibrate,. We could not get the speedo to work. Someone told me that the ECU changes the signal from the original speedo or the speedo has something in it to change the signal wave so aftermarket speedos will not work. The tach read 1/2 of what it should even when we tried all the different toggle switchs. Any suggestions?
    Image Unavailable, Please Login
     
  2. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
    72,740
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    #2 No Doubt, Nov 13, 2007
    Use a Stewart Warner or compatible speedo sensor instead of Ferraris OEM Veglia square wave sensor in the tranny.
     
  3. eric355

    eric355 Formula 3
    Silver Subscribed

    Nov 30, 2005
    1,230
    Toulouse (France)
    Full Name:
    Eric DECOUX
    #3 eric355, Nov 13, 2007
    The ECU does not change the speedo signal. On a F355, the speedo is direcly fed by the speedo sensor with a clean square wave signal (on a km/h speedo, it is about 227 Hz @ 120 km/h). Then the speedo divides by 2 the frequency of this signal in order to fed the engine ECU (Motronic) AND the suspension (ECU).
    So I can not see any reason why your speedo is not working. Measure the voltage of the sensor signal. It should flip between 0V and 12V when you move the car.
    IF you do not install a circuit which simulates the frequency division, you will have some issues with the Motronic and the suspension ECU. The Motronic, at least, will not (probably ! ) open the exhaust by-pass valve because it will not be able to know in which gear you are (gear estimation based on car speed and engine RPM). And the suspension ECU, thinking the car is not moving, will never stiffen the dampers and will set the warning light after some engine starts.

    For the tach, the engine ECU generates a square wave signal but I have not yet measured the relationship between its frequency and the RPM. The WSM is not very clear on this subject. If you are out by a factor 2 it should not be a big issue to solve that.
     
  4. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
    10,244
    U.S.A.
    Full Name:
    goth
    #4 gothspeed, Nov 13, 2007
    Looks good :)! Is that tach available in nero???...........;)
     
  5. CRAIGF355

    CRAIGF355 Formula 3

    Nov 13, 2005
    1,019
    NJ
    Full Name:
    CRAIG ANDERSON
    #5 CRAIGF355, Nov 13, 2007
    Yup! The 550's have black tachs. I was also thing about doing this glad to see some has done it. looks good
     

Share This Page