Electronic Fuel Injection System: Notes
NOTE:
Only those components directly used in the Constant Idle Speed system will be covered in this section. For information on fuel injection system, refer to appropriate FUEL INJECTION article.
The LH-Jetronic fuel injection system consists of 3 functional sections: ECU, fuel system and sensors. ECU receives and evaluates readings from various sensors around engine. Microprocessor evaluates variations in engine running conditions, calculates correct amount of fuel to be injected, and produces corresponding signals to injectors. It also operates air control valve for constant idle speed by regulating airflow opening. See Fig 1 .
Air mass meter measures air drawn into engine by means of a wire filament located in intake air stream. A temperature of 212°F (100°C) is maintained at filament. Current needed to maintain temperature at filament is measured, providing precise information on air mass entering engine.