I have a 94 eg and I did not have a tach from the factory. I pulled a cluster out of a 92-95 4dr auto (had a tach) and plugged it all up. Everything worked but the tach seems to be very unresponsive and the tach sort of bounces around. It is semi accurate but nothing like it should be. Any ideas on what the problem is? Cluster or otherwise?

 

look for a ground problem.

it sounds like it might be a problem with the cluster though.

see if you can find the wiring diagrams in a helms manual or better yet a civic factory service manual and find out for sure what's wrong with it

 

I had the same problem on mine. And mine was a stock tach! It was a loose ground, but was odd, because the ground was on the alternator itself. Check to make sure that the plug is pushed all the way in. Also if you know how, I would suggest taking the cluster back out, take off the plastic bezel, and make sure the needle can move freely. If you don't know how, either search a DIY, or get a mechanic to look at it.