On my 1999 civic, the tach reads way too high all the time until drove for a little bit. After you drive for 5-10 mins, the idle is right but the rest is still off. Any help or suggestions?

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I will add, this started this morning and I first noticed it when the tach spiked to 7k when idling and went back to normal.

 

It's broken... either replace it with another used one, a new one from Omni Power, or search for the thread on how to re-solder the various components inside the tachometer if you have the ability... or send it to someone who does.