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Mixture Control Unit

The air flow sensor contains a plate mounted on a hinged lever which moves in a cone shaped venturi. All engine air is drawn through this sensor. The plate moves as air passes through, pulling the hinged lever up or down. This raises or lowers a fuel control plunger in the fuel distributor, determining the amount of fuel to be injected into each cylinder. The movement of the plate is controlled by air flow, cone shape of venturi, a balance weight, and fuel pressure.

Fig 1: Bosch CIS Lambda Fuel Injection System Diagram (Typical of All Models - Details May Vary)
G09310431Courtesy of NOT AVAILABLE
NOTE: Air flows UP through the sensor on most inline engines, and DOWN through the sensor on V6, V8, and turbocharged engines. The direction of air flow does not affect system operation, it is changed for convenience of routing air flow.

Fuel distribution can be equal only if the pressure to each injector is equal. Pressure regulating valves in the fuel distributor equalize system pressure. These valves are adjusted during assembly of distributor and cannot be adjusted in service.