Fuel Injection System - MOTRONIC CEC: Description
The Motronic Emission Control System is an electronically controlled, computerized engine system which controls fuel injection and ignition timing as well as air/fuel ratio.
The Motronic Control Unit (MCU) is the "brain" of the system. Various engine sensors supply the MCU with operating information including airflow, air temperature, throttle position, coolant temperature, engine speed, piston position and oxygen content of exhaust gases.
The MCU uses this information to determine engine operating conditions, and adjusts timing and fuel ratio accordingly. The MCU is located behind the speaker in the right kick panel of 635CSi and 735i models and in the glove compartment of the 325e, 528e and 535i.