Electronic fuel injection system The 16 valve engine is equipped with the Bosch LHJetronic electronic fuel injection system. An electronic control unit monitors the fuel/air ratio. The system includes an air flow meter which measures the mass flow instead of the volume flow, so that the fuel can be metered more accurately in relation to the oxygen content of the air. The engine is thus less sensitive to variations in the ambient temperature and atmospheric pressure. The engine power is unaffected when the car is travelling at high altitudes, such as in mountainous terrain. This fuel injection system makes the engine easier to start- whether hot or cold. The operation of the air mass meter is as follows: The air flows across an electrically heated platinum wire in a tubular air meter. A microprocessor measures the electrical energy necessary to maintain the wire at a constant temperature, which is a measure of the mass of air flowing across the wire. | | The intake manifold is equipped with one injection valve for every cylinder. The injection valve is fitted upstream of the corresponding intake valve an is controlled electro-magnetically by signals from the electonic control unit. The electronic control unit calculates the opening time for the injection valve to suit the engine running conditions, so that the quantity of fuel injected will be correct in relation to the quantity of air flowing to the engine. | 1. Fuel tank
2. Electronic control unit
3. Air mass meter
4. Throttle valve
5. Automatic idling control
6. Injection valve
7. Temperature sensor |
At the same time, the microprocessor senses the engine speed and temperature, which enables it to meter out the correct quantity of fuel to suit the requirements of the engine at all times. Moreover, the microprocessor incorporates a speed limiter which ensures that no opening signals will be transmitted to the fuel injection valves at engine speeds above 6000 rpm. The LH system is self-cleaning, since the platinum wire is quickly heated to about 1000°C every time the ignition is switched off. This burns off any deposits on the wire. Automatic idling control The Saab 16 valve engine is also equipped with a system which maintains the idling speed constant, regardless of the engine load. The automatic idling control system employs an electronically controlled valve, which ensures that the en- gine speed will remain constant, regardless of any additional load applied by the air conditioning, power steering etc. This system contributes to the high standard of comfort and is of particular benefit to the driver. | 
