Ok i have an autometer tach and i have it all wired up properly...but for some reason when i rev it will rev to 3k fine...but not go any higher...it will just drop to 1k...then when i come below 3k again it will start working...

this was org. on a civic, and it worked...but its now on my 300zx...i reattached the orange wire and everything else is properly wired...any suggestions..btw im tapped into the signal wire on the ecu..