ISX Injector Leak test

[JB Farm]

I didn't have any luck getting bubbles to show up. I think I'm going to replace them all. If one is bad, the others maybe aren't far behind. Am I correct to say an injector can be bad but not produce bubbles? If the injector has the bottom seat sealed good, I'm assuming there's still other failures that happen. Leakage between metering or timing portion of the injector to where you don't get the hydraulic action that's needed? Just curious is all, I'm assuming Insite would detect that type of failure also? Throw a code?