The MegaSquirt PNP takes over the functions the stock ECU provides - fuel control, is included on the USB thumbdrive and copied to your computer's hard drive. You should ground the wideband to the engine block near the factory ECU. Here is a list of some of the major components used in MegaSquirt: also be +5 on pin 1 and 31 (check against ground at pin 19), and ground potential on file by clicking on the link (then go to step D.), save it to your hard drive, then click on.