how to fix a jumping tach needle
Amsnow
Jumping tach needle
Q I have a VDO Xtreme tach with a MSD dip switch ignition on a Cat triple. I noticed the needle is fluctuating terribly, even on replay from runs last year. I also noticed that when I power up the sled the needle is real jerky compared to my other sled, which is very smooth.
A Re-verify all ground connections and that your voltage is above 11.5 volts DC. On my MSD the multi-spark under 3,000 rpm has an adverse effect on my tach reading. It will make the needle bounce around until I get over that RPM where the multi-spark is inactive. Also check the calibration switches on the back of the gauge by switching them and switching them back to their original setting. Rule of thumb on all electrical problems – always check the ground or run more grounds to the source and chassis when dealing with electronics.