[DeTomaso] Tach Problem

[Joel Montero]

Recently I redid my entire interior.  Of course, I had to remove the
tach when I took the dash out.  Now that I have everything re-installed
the tach is not working properly.  I can't imagine that anything changed
during the process so I am stymied.  

Here is what it is doing.  When the car is idling, the tach registers
higher than the actual idle speed by about 700 RPM. The needle stays at
1500 RPM as long as the engine speed is below that.  As soon as the
engine RPM exceeds 1500 RPM the tach responds normally throughout the
range.  As soon as the engine returns to idle, the tach registers 1500
RPM.  I have an electronic ignition and a tach adaptor.  However, I have
had those pieces installed for some time and never have had this problem
before.  Above 1500 RPM the tach is accurate.  

Any ideas?  

 

Joel