I just got a civic si and i noticed that the factory tach would jump around when givin the little d1616 some gas. The motor is running great so what I am wondering is how do i fix the problem? Do I need a new gauge cluster, sender or what? I have the honda manual but what i can't find out is where or how the tach is wired. if any body has had this same problem please help!
Thanks

 

For me, when I had a 90 CRX, it was the distributor, the ignitor was going bad, and caused the tach needle to jump like crazy every once in a while. After I replaced the ignitor, the problem never came back.

 

yeah replace the ignitor, or at least tighten it's connections within the distributor.