I use to start my car and about a 5 mins after while driving along the tach jus jumps from 0 to what ever speed im doing... but it stays on 0 for a while... Now i find out the other 240 im looking at does the same.. and i kno a frined with the same prob...

 

my gfs 240 has the same problem. if i remember the name correctly, its just called a speed sensor thats gone bad. i hear quite a few older civics have this problem as well

 

you are referring to the spedometer not tachometer i assume. pull out the speed sensor and clean it off, check all associate connections.