Tech Mark wrote:
Theoretically, as the stack acts like a capacitor, if the injector is disconnected while it is charged (during injector "open" phase) it will stay open as the stack cannot discharge via the ECU. Is this correct or will the charge decay fairly quickly, closing the injector?
Hello,
This simplified model not explain very well the crystal stack,the resistance(180-200 kOhm) was omitted...so you will have a self-discharge in a few minutes.But you can't be shure about the complete discharge of the crystal stack,in our captures you can't see this self-discharge current(only a few mA ,please look at the attached image for this magnified current ),this is the reason why ECU put to gnd ij+ to cut injection.
Again simplifying the entire process,you must move some electrons to excite the crystal structure and make it "fat" and after some hundreds of us you must remove the same number of electrons from the crystal structure and make it "slim".Moving and removing of electrons will give you the current,the presence of electrons on one side of crystal structure will give you the voltage... from this perspective I used the simplified model with capacitor
Anyway the big problems with this type of injectors was the shorting of the crystal stack(this can be detected by ECU or measured with a multimeter),excessive back leak,and hydraulic command of needle(back leak test with injectors unlugged or with engine running)...For me was enough to capture the current af all injectors to see if one of them work bad/not work.
If someone need more info then the solid-state physics have more answers
Regards