Wrong RPM? | FerrariChat

Wrong RPM?

Discussion in '308/328' started by montreal328, Nov 3, 2009.

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  1. montreal328

    montreal328 Formula Junior

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    Hi! Just got myself a 1987 328 GTS, It's in great shape, but it's got a few snags...
    The RPM indicator seems to indicate about 1/2 of actual RPM: at 60 MPH it only reads 1500 RPM.... I never got them past about 3200 for fear of redlining the thing...
    Anybody ever heard of that?
     
    montreal328, Nov 3, 2009
    #1
  2. Doug

    Doug Formula 3

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    Tachs can go bad. No need to worry about redlining without a tach if your speedo is correct. The owners manual states maximum speed in each gear. Just stay below that speed for a max shift point until you resolve the tach issue.
     
    Doug, Nov 3, 2009
    #2
  3. f1lupo

    f1lupo Formula Junior

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    funny I have the exact same problem with my 87 328GTS except my tack won't go over 2,000rpm..I asked Framk over at FOO when the FCA had their tech session event last month and he said its 95% that the tach has got to be replaced and 5% that there could be a loose connection to the tach itself....I really can't be bothered looking into it myself as the car runs great and I was raised on driving stick cars and hardly ever look down to my tach will driving
     
    f1lupo, Nov 4, 2009
    #3
  4. BOKelley

    BOKelley Formula 3 Silver Subscribed

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    BOKelley, Nov 4, 2009
    #4
  5. gerritv

    gerritv Formula 3

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    If it is reading 50% (verify that with an external tach) check what they did to the ignition system. If it has electronic aftermarket, then that is the reason. some aftermarket ones need a pulse doubler or similar tach modification.

    Gerrit
     
    gerritv, Nov 5, 2009
    #5
  6. montreal328

    montreal328 Formula Junior

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    How can I tell if there is after-market ignition mods?


    Eric
     
    montreal328, Nov 5, 2009
    #6
  7. gerritv

    gerritv Formula 3

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    Hi Eric
    Post some good photos of the LH side of engine bay. that will spark a flurry of comments about whether it is original or not :)

    Gerrit
    http://dino308gt4.com
     
    gerritv, Nov 5, 2009
    #7
  8. hardtop

    hardtop F1 World Champ

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    Tachs with 3.2 motors go bad all the time. It is one of the very few items on 328's that are universally troublesome. They can be rebuilt. Do a search on the subject and find places to send it.

    Dave
     
    hardtop, Nov 5, 2009
    #8
  9. CliffBeer

    CliffBeer Formula 3

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    CliffBeer, Nov 5, 2009
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  10. montreal328

    montreal328 Formula Junior

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    Last edited by a moderator: Sep 7, 2017
    montreal328, Nov 9, 2009
    #10
  11. Gatorrari

    Gatorrari F1 World Champ Silver Subscribed

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    My tach did exactly the same thing when I bought the car. I could have had it rebuilt, but since the numbers on the dial had also faded, I elected to replace it entirely, and I got a real good deal on a new tach from Ricambi.
     
    Gatorrari, Nov 9, 2009
    #11
  12. montreal328

    montreal328 Formula Junior

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    The Gremlins are gone... With no warning at all the thing started to work right (almost, maybe 10% off), a case of humidity?!? Hum...
     
    montreal328, May 13, 2010
    #12
  13. red3555gtb

    red3555gtb Formula 3 BANNED

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    FoO had a tech session last month?
     
    red3555gtb, May 13, 2010
    #13
  14. JV's89

    JV's89 F1 Veteran Owner Rossa Subscribed

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    Be prepared for a relapse. Mine did the same thing. I've had two 328's and both eventually needed tach rebuilds. I sent them to Palo Alto speedometer for repairs and am very pleased with their work. http://paspeedo.com/
     
    JV's89, May 13, 2010
    #14
  15. montreal328

    montreal328 Formula Junior

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    Well... Seems gremlins are not totally gone, When I started the car yesterday, RPM was off again. After driving 10 mins. It was back to normal!?!
     
    montreal328, May 19, 2010
    #15
  16. sammyb

    sammyb Formula 3

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    Needs a rebuild. Of course it might work off and on for years. (My Dodge 600ES convertible with a dreaded digital dash started off-and-on reading 0 on the speedo in 1992 and it worked that way until 2008 when I finally elected to replace the $50 speed sensor. Works flawlessly now.)
     
    sammyb, May 19, 2010
    #16

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