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cak cak is offline
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Join Date: Jan 2007
Location: Palo Alto, CA
Posts: 269
tachometer bounce when cold

My 73.5 T (still with CSI and CDI) has started displaying some tachometer needle bounce - especially when cold, especially at low RPMs. For example: when I start the car cold, the needle indicates more or less correctly (by ear) at 1500 rpm or above, but when I ease the hand throttle down to 1200 or so, it tends to drop to 0 then bounce back. As soon as I drive away, the indication is smooth and about what I'd expect.

As the car warms up, this gets better, so I'm suspicious of a loose connection, perhaps a faston connector that is not fully seated. Just not sure where to start looking!

There's no obvious miss, so I don't suspect the points, but I'm willing to look anywhere...

Thanks.

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Chris Kantarjiev
73.5 911T Targa
and the rest: 66 TR4A 69 FJ40 70 GT6+ 00 2.5RS
Old 10-30-2007, 10:46 AM
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Join Date: Oct 2003
Location: Scottsdale,Az
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Check connections and also check your battery...when my battery started to die my fuel and tach guage started bouncing around
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Frank
1980 SC Cab Conversion (sold)
1974 914 2.0 RIP rear ended

Looking for a 996 Silver Cab 2002-2004
Old 10-30-2007, 10:51 AM
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Peter V
 
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Join Date: Sep 2007
Location: San Pedro Ca.
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Porsche Crest Bouncey Tachy

Quote:
Originally Posted by FenderGuy View Post
Check connections and also check your battery...when my battery started to die my fuel and tach guage started bouncing around
Yep, mine too until I replaced my alternator and my battery was on full charge.
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Old 10-30-2007, 10:59 AM
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cak cak is offline
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Thanks, but my battery and alternator are fine, and all the rest of the gauges are solid. This is just an issue with the tach, and only at low rpm...

It's perhaps not so much that it bounces, as that it drops to zero and returns.
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Chris Kantarjiev
73.5 911T Targa
and the rest: 66 TR4A 69 FJ40 70 GT6+ 00 2.5RS
Old 10-30-2007, 11:02 AM
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Clean the ignition points and check the gap.

Old 10-30-2007, 11:30 AM
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