Sensors

The air mass meter (1), measures intake air mass. The ignition coil (5), supplies the control unit with information on engine speed through terminal 1. The ignition pulses provide information on both engine speed and when injection should begin.
The temperature sensor (3), senses coolant temperature. Sensor resistance decreases as temperature increases.
The oxygen sensor (6), senses oxygen content in the exhaust gas. Oxygen content is a measure of combustion effectiveness. The throttle valve switch (2), senses throttle valve position. The throttle valve switch has two functions, a microswitch which closes at engine idle and a switch that closes at full throttle.
The starter motor (7), signals the control unit when starting the engine.