I have a 1990 crx dx. the tachometer is haywire, but there are no changes in the speed of the engine. also i have observed it while doing a variety of things, turning, turn signal, etc and those things make no difference. i have read elsewhere that this could be indicative of fault in the ignition system. i replaced the plugs, wires, distributor cap, and ignition rotor. this "cured" the problem for about 100 miles. Need help. Thanks

 

I've read on here that it could be your ignitor.