Fuel Injection - BOSCH AFC - EUROPEAN Models: Description
The Bosch Air Flow Controlled (AFC) electronic fuel injection system uses sensors to detect engine conditions. System consists of airflow meter, sensors, switches, air cleaner assembly, Electronic Control Unit (ECU), throttle chamber, air/fuel pressure regulators, injectors, and connecting wiring and hoses. See Fig 1. The ECU receives sensor signals to determine amount of fuel and length of time that fuel is to be injected into engine.
An airflow meter, mounted between the throttle chamber and air cleaner, measures amount of intake air. Fuel injector on time is based on amount of intake air required for one rotation of engine. System maintains a constant fuel pressure and accurately balances air/fuel mixture under all operating conditions.
Beginning with 1977 model year, BMW models have a high altitude compensator. Altitude compensator should be hooked up if vehicle is to be operated above 4, 000 feet. The altitude compensator is automatic on all other models. The intake air sensor transmits air flow information to the ECU while the distributor supplies engine RPM data. See Figure.
The 1979 BMW 528i, Jaguar XJ6L, and Volkswagen Type 2 (California) models incorporate an oxygen sensor into the Bosch AFC fuel injection system. The system consists of an oxygen sensor mounted in the exhaust manifold, a modulating or frequency valve, a 3-way catalytic converter and a modified electronic control unit.