The 1975 and later models are equipped with electronic fuel injection built under Bosch patents. The Bosch L-Jetronic system precisely controls the fuel injection to match the engine requirements, reducing the emissions and increasing driveability.
The electric fuel pump, pumps fuel through a damper and a filter to the pressure regulator. The six fuel injectors are electric solenoid valves which open and close in respect to signals from the control unit.
The control unit receives input from various sensors to determine engine operating condition:
- Air flow meter: measures the amount of intake air.
- Ignition coil: engine rpm.
- Throttle valve switch: amount of throttle opening.
- Water temperature sensor or cylinder head temperature sensor: temperature of coolant or engine.
- Air temperature sensor: temperature of intake air (ambient temperature).
- Thermo-time switch: signal used to control cold start valve fuel enrichment when the engine is cold.
- Starting switch: signals that the starter is operating.
- Altitude switch: used on 1977-78 (California) models to signal changes in atmospheric pressure.
- Exhaust gas sensor: used in 1980 California models and all 1981 and later models to measure the oxygen content of the exhaust gas.
The sensors provide the input to the control unit, which determines the amount of fuel to be injected by its preset program. The L-Jetronic fuel injection system is a highly complex unit. All repair or adjustment should be left to a qualified Nissan technician.