Mondial 3.2 tachometer problems....help! | FerrariChat

Mondial 3.2 tachometer problems....help!

Discussion in 'Mondial' started by CliffBeer, Jun 13, 2006.

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

  1. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #1 CliffBeer, Jun 13, 2006
    The tachometer on my '88 3.2 Mondial has a problem - it reads about 1/3 the actual rpm. In other words, idle reads about 300rpm and 70mph reads about 1,100 rpm. Anybody have any idea why the tach started reading this way all of a sudden? Worked just fine/accurately the prior time I ran the car about a month ago. Battery is fully charged. Thanks in advance for any help!
     
  2. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #2 CliffBeer, Jun 13, 2006
    Brief addition to the above... I measured the resistence at the pin connector to the magnetti/marelli control box for the engine speed sensor at it's right around 500 ohms which I believe is in the right range. So, this makes me think it's not a fault of the sensor but rather something more towards the tach itself. Anyone else ever have this problem??? Thanks.
     
  3. snj5

    snj5 F1 World Champ

    Feb 22, 2003
    10,213
    San Antonio
    Full Name:
    Russ Turner
    #3 snj5, Jun 13, 2006
    I would agree that it is probably the indicator, as the indicator takes the signal directly off the 3.2's single Microplex ignition ECU (located left rear lower firewall). If the engine is running well, then perhaps the problem is more toward the indicator.
    Prior to removing the indicator, I would try removing the connector from the Marelli ECU at the firewall, cleaning the contacts, firmly re-seating the connector and re-checking.
    Good luck!
     
  4. ProCoach

    ProCoach F1 Veteran
    Owner

    Sep 15, 2004
    5,465
    VIR Raceway
    Full Name:
    Peter Krause
    #4 ProCoach, Jun 13, 2006
    It's the tach. There is a trimmer potentiometer for calibration on the pc board in the tach and the wiper carbon gets dirty. Stabilant to the rescue! If that doesn't fix it, replace the pot. N. Hollywood or Palo Alto Speedo can do it.
     
  5. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #5 CliffBeer, Jun 14, 2006
    Hi - thanks! I'll check it out and apply some stabilant where appropriate. Noticed you're a Lola fella - I'm buying a GT40, also designed by Eric Broadlee, should be a great car with all the US hp in such a small and lightweight chassis.
     
  6. CliffBeer

    CliffBeer Formula 3

    Apr 3, 2005
    2,198
    Seattle, Washington
    Full Name:
    Cliff
    #6 CliffBeer, Jun 14, 2006
    Thanks, good advice. Just did that exact drill tonight and unfortunately it's still reading funky. It wasn't a waste of time however as the contacts at the connector did look a little corroded....and, I got to tighten up the emergency brake adjuster while I was in the neighborhood of the Marelli unit! Thanks again!
     
  7. Lenvo65

    Lenvo65 Formula Junior

    Apr 3, 2005
    293
    Bergen Cty NJ
    #7 Lenvo65, Jun 15, 2006
    The seller suppossedly sent the Tach out to Palo Alto speedo to be rebuilt and on the drive home it seemed to work fine, but now the it jumps are over the place especially when I get above 4,000 RPM - I will have to try the above recommended contact cleaning as well.

    Two follow-up questions:

    Where is a good place to by Stabilant? and How do you get the tach out of the dash?
     

Share This Page