mgs
[Top] [All Lists]

RE: Strange Tach

To: "'Jay Tilton'" <jtilton@vt.edu>
Subject: RE: Strange Tach
From: "David M. Hall" <dhall@hp-vcd.vcd.hp.com>
Date: Wed, 29 May 1996 14:02:43 +0100
Hmm.. Just had my alternator replaced, and PTS is still around on
warm days (80+ F).

Dave Hall
72 MGB/GT

Jay Tilton wrote:
> Bert.Otten@nni.nl wrote:
> 
> >But apart from this slight nuisance ;-) , I encountered some other
> >thing. When the engine revs above, say 4000 rpm, the tach starts to
> >swing wildly up and down sometimes reaching 0 and then again to 6000
> >rpm.
> 
> Unfortunate past experiences in my 77B have led me to hypothesize that
> the Psychotic Tachometer Syndrome (PTS) is a sign that the alternator is
> just about fried; probably something to do with intermittent currents or
> big changes in voltage.  Every time I've observed PTS in my car, the
> alternator stops functioning within a few days, and PTS doesn't return
> after installation of a freshly rebuilt unit.  Your car with a known
> shot generator lends some support to this theory.  See if it doesn't go
> away with a new generator.
> 
> My tach also does some a similar number when I shut the car off while
> the cooling fans are going.  It kicks from idle up to about 3000 RPM
> while the fans are spinning down.  I think in that case, after cutting
> power to the fans they actually start working as DC generators, feeding
> current back into the system.  There's a less pronounced effect with the
> heater fan.  Fortunately that doesn't seem to be doing any damage to
> anything.
> --
> Jay Tilton  |  jtilton@vt.edu
> 
> 


dhall@vcd.hp.com

<Prev in Thread] Current Thread [Next in Thread>