As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKE OFF ROLL, V2 SPEED AUTOMATICALLY CHANGED FROM 167KTS TO 130KTS V REF +-15 WHITE BUG (SHARKSTOOTH) SHOWED SPEED OF 130KTS WHICH WAS BELOW THE RED LOW SPEED AWARENESS TAPE. FMC #2 WAS MASTER. THIS ANOMALY SHOWED ON BOTH PFD'S. GROUNDED - YES. PERFORMED B737-900 FIM 34-61 TASK 801, FMC BITE SHOWS NO INFLIGHT FAULTS NO OTHER DEFECT NOTED.