I previously owned an autometer tach. That worked fine until it slowly started crapping out. The revs would rise WAY too fast and it wouldn't go below 2500 rpms...then 5000 rpms...back down to 1200 rpms...then finally it just got stuck at 8500 rpms and wouldn't budge any lower. So I removed the autometer tach and just ran tachless for awhile. Figured I'll just buy an EX gauge cluster and stay OEM, maybe its just my tach thats F*ed up.
Fast forware a few months after I finally stop being lazy and buy the cluster.

Just installed it and WHADDYA ******* KNOW??!? The tachometer doesn't budge AT ALL. Its as if there isnt even any power to it.

Any ideas?

Oh yeah, its a 92 CX

...could it be possible that 92 CXs didnt come with the wire in the harness for tachometers?

 

see if theres a blue wire running out of behind the guages under the hood. and then to the distributer. it should be wired fine. maybe you need a new ignitor.