I have an Autometer 5" monster tach, it reads fine below like 4k, but after that it jumps like crazy! It is really pissing me off. I have tried running the tach wire directly off the coil, and also near the fire wall, where the stock tach wire ends and is capped from the factory. I have a D16z6 it is vtec, and vtec engages about where the tach starts going crazy. Is my tach messed up, do I need to use thicker wires maybe? The power is run off the ignition wire in the dash behind the cluster, and it is grounded on the metal kick panel above the pedals. Is my coil bad? I have no idea what to do, please help, or I am just going to sell the POS.

 

Recheck your wiring, especially the ground. If it doesn't fix it, then throw your tach away. You dont need thicker wires. Also, make sure the cut looped wires in the back are not reconnecting.

 

like he said check the ground

 

Check all the connections. It sounds like your tack is either bad or it is getting a mixed up signal.