Well, Hobbit's information is really great. I was kind of hoping that I could measure RPM from the crankshaft position sensor but his information states: The 1NZ-FXE mill in the Prius uses a "36 minus 2" crank wheel, i.e. 34 teeth with a gap where two more teeth are missing. This conveniently maps to 10 degrees per tooth slot. The ECM syncs up with the base timing rate of passing teeth and then looks for the missing pulses as an absolute reference as to where the crank is. The cam "wheel" only has three teeth on it [at 90 degrees, thus a "4 minus 1" configuration] and works similarly. Here are some pictures of the real things, courtesy of Galaxee from Priuschat and her husband who spends his days armpits-deep in this stuff and brings home all the coolest discoveries. So, this is a problem but could also help me in another way. If this has power whenever the "ready" light is lit, then for sure I'd be able to get the "engine spinning" mod done. However, if I wanted to use this to calculate engine RPM, those two missing teeth would be an issue. If I took the measured frequency/36, there would be two pulses missing. If I took the measured frequency/34, it wouldn't be entirely accurate. Maybe if I take a snapshot every 200mS I can calibrate it. I need to think about this for a while.....
