PhillipM
03-17-2011, 07:21 PM
I have a weird one for you guys. My stock tach was getting up to 4k RPM and then would fall down and bounce around until the engine came back down below 4k. So, I was thinking that it finally kicked the bucket. I puchased an Autometer tach to replace it but am now getting the same results. The wierdest part of the whole thing is that when I put a scope on the engine and pull the tach signal directly off the coil tach output wire it gives me a clean reading all the way up the RPM band. Could this be a weak ground? Could the signal wire be falty? I'm just not sure. It did used to work at one time so I'm just chasing down the problem. I orginally thought that the coil may be bad but know i'm not sure.