I may end up being corrected here by a pico master user or tech, but I believe that you may be working with a piezo type injector. If I am correct you should be using a 3rd channel to monitor the injector ground, and from what I have read and understand is that piezo or pizzio injectors work with ceramic discs that warp with voltage being applied in one direction and then when polarity is reversed the discs warp the other way. Thus creating the movement to work a pintle off a seat by means of some mechanical linkage. A pintle hump in a waveform is created when a iron core rod moves through the magnetic field of a coil of wire that has voltage applied to it. A piezo injector does not operate in this manner and will never show you a pintle hump in the waveform. Just my opinion from what I have read.