During the early 1980s, vehicle technology changed significantly with the implementation of computer technology. Electronic Control Units (ECUs) were introduced to improve performance and efficiency. In the early days ECUs controlled just a handful of processes. Following advances in both electronic and computer technology, ECUs now control a vast number of electronic and mechanical processes. Signals transmitted from sensors located on the engine and chassis provide vital information to the ECU so that real time adjustments can be made. Engine speed, boost pressure, fuel pressure, cam timing, lambda and pedal position are just a few examples of the parameters measured by an ECU and the parameters it can control.