System operation (Discovery 1)

When the ignition is turned on, battery voltage is supplied to terminal 11 of the control unit. From the control unit, grounding of the main relay is supplied to terminal 4 (disconnectable grounding). After this, power is supplied through the relay from terminal 28 of the control unit to the four injectors and through terminal 25 to the ignition coils. From terminal 20 of the control unit, the grounding of the fuel pump relay is switched on and, through the inertia switch, the pump winding circuit is closed. The pump will operate for some time until the pressure in the system rises to the operating level.

The control unit determines the degree of throttle opening using the idle speed controller stepper motor based on the following signals:

• coolant temperature sensor (terminal 33)
• air temperature sensor (terminal 16) throttle position sensor (terminal 8) speed sensor (conclusions 31 and 32) absolute air pressure sensor battery voltage (terminal 28) ignition coil signal (terminal 11)

When starting the engine (up to a rotation speed of less than 400 rpm) the injectors deliver a larger amount of fuel than during normal operation. To prevent the mixture from becoming too rich, the fuel supply is stopped from time to time, for example, after 24 working cycles there are 8 cycles without fuel supply.

The material was taken from the specified website www.LRman.ru