I've been having problems with my idle to high. It doesn't sound like it but the tach says 1400rpm at idle. At 60-75mph, my tach reads about 3600rpm. If i floor it, it redlines. The engine sounds fine though. Could my tach be bad? It is the factory tach in the instrument panel. It is a 90 RS with a 305 tbi. Thanks for any advice.

 

I too have a 90 RS V-8 and I have the exact same problem. The engine sounds normal, but if I'm doing 75 or 80 mph my rpms are over 4000. Hopefully someone can help us trying to figure out what this problem is.

 

Well, it could be several things. First, can you get someone with a good master tach to check the RPMs at idle and tell you if it is idling at 1400.

If not, I would suspect the speedomoter is worn out (I doin't know whether the 89 has a mechanical or electrical speedo, but it could be a tired return spring, or a ground wire lose, etc.).