2003 - tach swings wildly upon reaching VTEC/7000 rpm

[ZCD76]

2003 bike with 2,900 miles. Yes 2,900 miles.

 

When I purchased it last fall w/approximately 1,800 miles on it, I don't recall any tach issues. However, the bike did not run so well. Had the injectors cleaned and flowed, new spark plugs (brisk silver plugs), changed the oil, and have run some fuel system cleaner through a few tanks.

 

Beyond that, I have a sebspeed windowed the clutch cover and installed a VFRNess. The issue is the bike runs fine (to the best of my estimation) and the dash works as it should but as soon as the tach gets to 7k/VTEC kicks in, the tach will suddenly swing past 13k and bounce around from ~10k to well past 13k and the fuel injection light will illuminate - sometimes dimly and briefly and sometimes it will fully light and stay lit until I let off the throttle. 

 

The bike seems to run fine. I have a digital voltage display and I never see more than 14.3-14.5 volts while the bike is running. 

 

I have read about the grounding issues and attempted to chase down everything. It does have a vfrness installed and all of the connectors have been taken apart, cleaned, and reconnected using dielectric grease. Anybody have any ideas?

[Cogswell]

Since you have more than one symptom (FI light also), it sounds like a possible grounding issue in the cluster or related.  For a bike that's been sitting for the better part of 15 years, a sketchy ground is a distinct possibility.   When electricity can't find its way back to source it starts taking any path it can find causing seemingly inexplicable problems.   BTW - dielectric grease is an insulator, essentially silicone - the prefix "di" meaning  "two", or "apart".   It's often used on connectors to seal out moisture or on spark plug boots.  On metal contacts with low voltage / amperage it can be problematic.  Oxgard is a preferred choice to keep corrosion at bay and promote conductivity.