Subaru Coupes/Sedans/Wagons 1985-1996 Repair Guide

SINGLE POINT FUEL INJECTION (SPFI) SYSTEM

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See Figures 1 and 2

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Fig. Fig. 1: Schematic of single point fuel injection system-1.8L engine



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Fig. Fig. 2: SPFI component locations

The Single Point Fuel Injection (SPFI) system is used on the 1.8L engine only. The system electronically controls the amount of injection from the fuel injector, and supplies the optimum air/fuel mixture under all operating conditions of the engine. Features of the SPFI system are as follows:



Precise control of the air/fuel mixture is accomplished by an increased number of input signals transmitting engine operating conditions to the control unit.
 
The use of hot a wire type airflow meter not only eliminates the need for high altitude compensation, but improves driving performance at high altitudes.
 
The air control valve automatically regulates the idle speed to the set value under all engine operating conditions.
 
Ignition timing is electrically controlled, thereby allowing the use of complicated spark advance characteristics.
 
Wear of the airflow meter and fuel injector is automatically corrected so that they maintain their original performance.
 
Troubleshooting can easily be accomplished by the built-in self-diagnosis function.
 

 
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