signal wire

[gman_128]

hey i have a 94 cavy with a 2.2l and i recently bought a tach and i hooked it up to the signal wire or a wire that came off the distributer and everything, when i start my car the tach reads 500rpm and thats normal idling rpm but when i rev the engine up to about what sounds like redline the tach reads 3000rpm and i know thats not right. so i figured that some how that signal wire can't read the rpm fast enough or something like that, could anyone help me fix it.

thanks

[jakegday]

sounds to me like its only reading half the rpms, i dont know about cavaliers made before 95 but on the ones made after 95 i know you need a tach adaptor for it to work right, UNLESS you can set your tach to 2 cylinders, then that would work also