My 91 civic lx 5spd 1.5 liter completely stock started every once and awhile having the rpm needle bounce all over the place motor runs fine but the gauge is telling me I'm going from 2k to 5k to 4k etc. It does it when cold but once warmed up the rpm gauge works as normal... I was told it could be a bad coil if so should I replace it or do the swap for an external coil I believe its just a cap off a prelude and some wiring? Thanks for any help btw reply to my email at tyrone.jason@gmail.com thanks

 

Could be a bad coil or just get another dizzy. My homie had this happen in his DA & replaced the dizzy & its koo now.

 

check your engine computer ground on the motor. It might be loose