The Pico explanation under injector current trace says
It is not however possible to calculate the time taken for the injectors spring to fully close the injector and cut off the fuel flow.
The Pico explanation under the voltage trace is for a different system, in which the current is rapidly cycled. I'm wondering if the spring has become weak in 360K miles, but I hate to just throw parts at it. That's what I bought the scope to avoid.
The closing should be seen in the voltage trace (as arjen states), by observing a "pintle hump" on closing, according to http://www.volvotips.com/index.php/850- ... -tutorial/. They acknowledge that it's hard to see.
Does anyone know how late is too late for this closing? The volvotips website says it should happen during the voltage decrease and not on the flat part of the curve. I've attached a screenshot of mine.