points for load and 16 points for speed. These 256 primary values are then modified by coolant temperature, intake air temperature, oxygen content of the exhaust, car battery voltage and throttle position - to provide 65,000 possible injector duration points. Digifant is unlike the earlier CIS and CIS-E fuel injection systems that it replaced, in that fuel injectors are mounted on a common fuel rail. CIS fuel injection systems used mechanical fuel injectors. The fuel injectors are wired in parallel, and are supplied with Constant System Voltage. The ECM switches the earth/ground on and off to control duration. All injectors operate at the same time (simultaneously, rather than sequentially) each crankshaft revolution; two complete revolutions being needed for each cylinder to receive the correct amount of fuel for each combustion cycle. Ignition system control is also digital electronic. The sensors that supply the engine load and engine speed signals for injector duration provide information about the basic ignition timing point. The signal sent to the Hall control unit is derived from a programme in the ECM that is similar to the injector duration programme. Engine knock control is used to allow the ignition timing to continually approach the point of detonation. This is the point where the engine will produce the most motive power, as well as the highest efficiency. Additional functions of the ECM include operation of the fuel pump by closing the Ground for the fuel pump relay, and control of idle speed by a throttle plate bypass valve. The Idle Air Control Valve (IACV) (previously known as an Idle Air Stabiliser Valve - IASV), receives a changing milliamp signal that varies the strength of an electromagnet pulling open the bypass valve. Idle speed stabilisation is enhanced by a process known as Idle Speed Control (ISC). This function (previously known as Digital Idle Stabilization), allows the ECM to modify ignition timing at idle to further improve idle quality. Digifant II inputs/outputs The 25 pin electronic control unit used in the Golf and Jetta receives inputs from the following sources: Hall sender unit (provides engine speed signal) Air Flow Sensor (provides engine load information) Coolant temperature sensor Intake Air Temperature sensor Knock sensor Additional signals used as inputs are: Air conditioner (compressor on) Car battery voltage Starter motor signal The Anti-lock Braking System (ABS), three-speed automatic transmission, and vehicle speed sensor are not linked to this system. Outputs controlling