Playback tach ??
 

Any ideas on what may be happing?
I don't have a race pack.:(

On the Playback tach
1st gear is real smooth to 6000

2nd gear it falls back an sits for a bout 1 second (in slow play back mode)
then climbs slowly and "hops" a bit. to 6000

3rd it falls back to the same spot climbs slowly
from 6300 on it starts" jumping & hopping" real bad.

I don't know what this is the tach looks smooth when making the run
the car doesn't miss or pop and runs a decent MPH 122 IN D/SA
.

Any help or ideas on what is causing this would help, thanks.

Re: Playback tach ??
 

All our playback tachs are jerky when played back
in slow motion ...particularly in high gear as they are
moving up more slowly.
On the shifts they drop back momentarily to the converter
stall speed as well have large ratio changes in our transmissions.
Despite this they provide a lot of information to us.

Re: Playback tach ??
 

x2

Re: Playback tach ??
 

Glen:Mines an older Autometer I bought used but it has always worked real well ! I would say check your ground---

Re: Playback tach ??
 

You may want to look at getting a noise filter to cleanup the power and ground.

That and check the grounds. The majority of issues we find at work are ground related.