just received my 4425 automotive pico this morning, the max input is 200V , my question is that do i need to use an attenuator per channel when using with spark and injectors? the the max input value for each channel or when all channels are live?. thanks
You will need to use an attenuator when you make a direct connection and suspect that you may exceed 200v. This both protects the scope and allows you to scale for the higher voltage (when you select the attenuator software probe). An example would be any primary ignition signal which will kick over 400v. No worries with using the secondary test leads as these do not make a direct connection and the input to the scope is low voltage.
You will need an attenuator for each channel or there are many tests you will not be able to do. For example, a basic V6 waste spark primary ignition analysis.
When in doubt, use an attenuator. You can always just remove it after you confirm the voltage levels do not require it. I don't think you would need it for any gasoline injection.