Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Chip tuning refers to changing or modifying an EPROM chip in a car''s or other vehicle''s electronic control unit to achieve better performance, whether it be more power, cleaner emissions, or better fuel economy. This was done with early engine computers in the 1980s and 1990s. Today, the term chip tuning can be misleading, as people will often use it to describe ECU tuning that does not involve swapping the chip. Modern ECUs can be tuned by simply updating their software through a standard interface, such as OBDII. This procedure is commonly referred to as engine or ECU tuning. ECUs are a relatively recent addition to the automobile, having first appeared in the late 1970s.