Originally Posted by Al Hounos (Post 83700)

I understand wasted spark, but doesn't the MS tach output read the same as waht you see in megatune? In other words, the same as it is reading from the CAS input, and NOT the spark output, which would read 1/2 speed as a 2cylinder?

Originally Posted by Al Hounos (Post 83700)

I understand wasted spark, but doesn't the MS tach output read the same as waht you see in megatune? In other words, the same as it is reading from the CAS input, and NOT the spark output, which would read 1/2 speed as a 2cylinder?

Originally Posted by mazdasly75 (Post 83700)

I don't think you can use this signal since it's a square signal, you would read 0.1V by a multimeter.

Originally Posted by mschlang (Post 83736)

As long as your MT tach is reading correctly, the tach output pin will read the same rpm.



I think there is confusion between the terms "spark output" and "tach output". In post 18, you said that you built two tach output circuits usings VB921s to fire the coils. What you actually built were spark outputs. The tach output circuit (in my first post) creates a circuit to provide a signal to the tachometer. It has nothing to do with the circuits that fire the coils.