mh (nice little rotary btw
) ,
1. Make sure you measure/tap by the injector for starters, I frequently have problems at the ECU for unknown reasons.
2. Some older cars (and who knows what else) have a positively switched circuit. So that you can locate one (of two) injector leads that will give you an "inverted" gph reading. I added a "inj trig" setting to the setup recently that you can set to 1 to see if that fixes things. If that is what is going on then the first picture looks right.
the atmega has a large resistor in series with the signals and a zener to clamp it at or below 5 volts, it is meant for a 14+ volt injector system. The atmega needs at least 2.5 volts to register an "on" signal, so 0 to 0.5 won't even register.