Fuel INJ - MPFI System: Description

The Mazda computerized engine control system monitors various engine/vehicle functions to control engine operation and lower emissions while maintaining good fuel economy and driveability.

The Electronic Control Unit (ECU), through various input sensors, monitors battery voltage, engine RPM, amount of intake air, cranking signal, No. 1 cylinder ignition timing (Turbo), intake temperature, radiator and engine coolant temperatures, oxygen concentration in exhaust gases, EGR amount (Turbo), throttle opening, atmospheric pressure, gearshift lever position, clutch engagement, braking, power steering operation, and A/C compressor operation.

On the 626 and 626 Turbo, the ECU governs operation of fuel injection system, by-pass air control system, fuel evaporation system, and EGR control system. On the 323, the ECU controls operation of fuel injection system, idle-up system, fuel evaporation system, and ignition timing.

The electronic control unit has a built-in fail-safe mechanism. If a fault occurs while driving, the ECU will substitute pre-programmed values. Driving performance will be affected, but the vehicle may still be driven.