Subaru Coupes/Sedans/Wagons 1985-1996 Repair Guide



See Figures 1 and 2

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Fig. Fig. 1: Schematic of MPFI system-non-turbo equipped models

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Fig. Fig. 2: Schematic of MPFI system-turbo equipped models

The MPFI system supplies the optimum air/fuel mixture to the engine under various operating conditions. System fuel, which is pressurized at a constant pressure, is injected into the intake air passage of the cylinder head. The amount of fuel injected is controlled by the intermittent injection system, whereby the electro-magnetic injection valve (fuel injector) opens only for a short period of time, depending on the amount of air required for 1 cycle of operation. During system operation, the amount of injection is determined by the duration of an electric pulse sent to the fuel injector, which permits precise metering of the fuel.

All the operating conditions of the engine are converted into electric signals, resulting in additional features of the system, such as improved adaptability and easier addition of compensating elements like ignition timing. The MPFI system also incorporates the following features:

Reduced emission of exhaust gases
Reduction in fuel consumption
Increased engine output
Superior acceleration and deceleration
Superior starting and warm-up performance in cold weather since compensation is made for coolant and intake air temperature
Good performance with turbocharger, if so equipped