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Home >> Subaru >> 1989 >> RX Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Theory/Operation - EFI >> Computerized Engine Controls >> Fuel Injection
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Fuel Injection

The electronic fuel injection systems, Multi-Point Fuel Injection (MPFI) and Single Point Fuel Injection (SPFI), supply optimum air/fuel mixture to engine under various operating conditions. This is determined through use of various sensors and a control unit. Amount of fuel injected is determined by duration of an electric pulse applied to fuel injector(s).

SPFI systems are a throttle body type, using a single fuel injector mounted in a throttle body atop an intake manifold. MPFI systems use a separate injector for each cylinder, mounted in intake manifold, next to intake valve.