How do u know it's not working on the car? The easiest way to check this is when it's cold, disconnect the IDSV and it should run like shit, then plug it back in and see if there's a difference, it could be something else i.e a temp sensor????? I don't know if you have done this already but i had a similar problem that turned out to be somrthing else. I don't know what the correct input voltage is, but if 6.5V is not correct then the ecu or whatever is obvioulsy sending some different signals for a reason. i.e a sensor from elsewhere.