I installed an analog tach in my 2005 prius and it is reading 500 rpm under compared to the obd2 rpm i'm getting off of the torque app. I followed http://techno-fandom.org/~hobbit/cars/tachack/ this guide for the tach installation. Does anybody know why it would be reading pretty much exactly 500 rpm under?
It's a ebay tach, 2" 52MM RPM TACHOMETER BLUE DIGITAL LED AUTO TACH GAUGE METER W/ HOLDER CUP US. It has a setting for 4, 6, and 8 cylinders. I'm 99% sure it's set on the 4 cyl setting as that was the first thing i've suspected.
cheap no name gauges tend to be very inaccurate until they fail completely in a short time. autometer or vdo would be good choices, but you should go with digital.
