A trigger signal runs into this module, is converted to a square wave and is then sent to switch the coil. In addition a signal is also sent to pin 1 of the main LH ECU providing the trigger for the fuel injectors. This additional trigger is crucial and should always be checked first with any potential fuelling problem. The hot wire in the air mass meter creates a variable voltage output relative to the induction air passing it. In this way engine load is measured.
Fuel supply is conventional but some times there are two pumps - priming and main.
If there are two both are controlled by the same fuse pump relay. The system works on intermittent injection - all injectors are triggered together, twice per cycle. The basic fuelling curve is calculated from the coolant sensor mounted in the water jacket at the back of the cylinder head just below the inlet manifold normally with a blue plastic connector socket. A standard fuel rail supplies the injectors, with a control regulator on the return side to maintain correct pressure. There is a limited amount of idle speed adjustment via the throttle disc but essentially this should be ECU-governed.