Tach reading high

Last week I had my super mag III upgraded to a IV and now my tach reads higher than it should. At idle it is off 1000 rpm and goes off even more the higher I rev it(@4,000 it reads 5500). Before I put the IV in it worked fine. This is an autometer tach with the inductive pickup. I moved the coil wire and no difference. I do run MSD super conductor wires b/c without them my tach doesn't even come close to registering right. My rev limiter works fine. I have changed nothing since last time I ran it, just the mag.
Thanks,
Adam

 

check the archives. lots of info on this well known problem. opinion seems to be they never really work right and the more juice the more interferance there is . the only way for sure is to go with a mechanical tach. best of luck

 

Call Mallory and ask them. I'm sure you aren't the first to have a problem like that, and they may have a simple fix.

 

Found my problem. I had a ground in a connector that had partially pulled out.