It's been years since I installed my AVC-R, but I remember something in the install manual that explains this issue. I think is has to do with whether you connected the RPM wire or the Injector duty cycle wire to your AVC-R. Since your AVC-R is showing you your injector duty cycle.....you have obviously connected the inj. wire. The RPM is then somehow calculated and is not accurate in the higher RPMs (see manual for details.)