Q What does DBW, DBC, 16-bit, 32-bit and floating point mean?
DBW stands for drive-by-wire. Newer Subaru models are known as DBW because they use an electronic throttle control rather than a physical connection between the throttle and the throttle body. DBW ecus that are frequently tuned include these USDM models – 04+ STi, 06+ WRX, 04+ Forester XT, 05+ Legacy GT, 05+ Baja Turbo, and the 05+ Outback XT. The reason this distinction is important is that DBW data is arranged and stored in a different manner than the non-DBW ECUs. You will also see DBW ecus mentioned with the terms “32-bit” and “floating point”. This refers to the largest size data element in the rom (32-bit) and also how the data can be stored on the ecu (float). Non-DBW ECUs, sometimes known as drive-by-cable (DBC), are 16-bit and do NOT use floating point values. These include models such as the 01–05 WRX (all markets).
There are a few minor exceptions, such as a 32-bit/floating point rom that is DBC, but these are not very common.