wumpus wrote:I strongly suspect the computer counts the number of times it sends pulses to the sparkplugs and and moves a motor to indicate RPM. I'm pretty sure I've seen dashboard mountable tachs that simply read the ODB(II) data and displayed it in LED format. I also recall somebody claiming that during a sportbike scandal where a certain engine was supposed to rev to umpty-up warp rpm, the engineers who calibrated it knew they where lying since they were moving a stepper motor from data in the computer. YMMV.
I'm pretty sure whatever method is used is exactly the same as the speedometer. One reads before the transmission, one reads after.
Users browsing this forum: Bing [Bot] and 6 guests