Bouncing aftermarket tachometer

[amateur37]

Need help guys, Just installed an aftermarket tachometer(Auto Gauge Brand) on my carburated Nissan Sentra LEC and the needle's bouncing and not accurate, giving an idle speed of 1600rpm which is supposed to be only 850 to 900RPM in idle. It has a selector switch for the Number of engine cylinder(I turn the switch to 4 'cause the engine is only 4cylinder) In total the tach gauge has 5 wires, RED WIRE-directly connected to +12v battery, WHITE WIRE-connected to +12v ignition switch, BLACK WIRE-connected to negative ground, ORANGE WIRE- connected to parking light so tach display will dim when light's turn ON and finally a WIRE that's connected to the engine's coil negative wire. What do you think the things that I should look in the car to remedy this problem. Any suggestion will be greatly appreciated wag lang change car-wala budget eh, thanks

[jick.cejoco]

Need help guys, Just installed an aftermarket tachometer(Auto Gauge Brand) on my carburated Nissan Sentra LEC and the needle's bouncing and not accurate, giving an idle speed of 1600rpm which is supposed to be only 850 to 900RPM in idle. It has a selector switch for the Number of engine cylinder(I turn the switch to 4 'cause the engine is only 4cylinder) In total the tach gauge has 5 wires, RED WIRE-directly connected to +12v battery, WHITE WIRE-connected to +12v ignition switch, BLACK WIRE-connected to negative ground, ORANGE WIRE- connected to parking light so tach display will dim when light's turn ON and finally a WIRE that's connected to the engine's coil negative wire. What do you think the things that I should look in the car to remedy this problem. Any suggestion will be greatly appreciated wag lang change car-wala budget eh, thanks

check and make sure your grounding wire is clean and tight and free of paint on the connection, then install a 0.25 microfarad capacitor between the negative terminal of the ignition coil and the ground parallel to the tachometer trigger wire