Dake

The digital tachometer on my 1986 Corvette is acting funny. It will report the correct revs up to about 4,000, but at that point it falls down again while the engine revs continue to climb. It will resume reporting the correct numbers when revs fall back to about 3,500. The car drives fine (well it did until it developed a miss yesterday, but I think that's a separate issue). I just replaced the tachometer signal filter and relocated it to the front crossmember near the power steering reservoir. Maybe something about extending the wires that far resulted in an amperage drop that is messing with the readout. That's the best guess I've got because I know the wiring is solid. Anyone else have a guess or ever had this problem?