MCU Engine Control System: Description
The MCU control system is named for and commanded by a Microprocessor Control Unit. This micro-computer is located in the engine compartment and is capable of controlling engine air/fuel ratios, air injection, and on some models, canister purge, spark retard and idle speed.
The MCU system is used on some 4 cylinder engines, 6 cylinder truck engines in California, and on most V8 engines. The system consists of the MCU module, air/fuel control and air injection solenoids, engine sensors, and related circuitry.