M

MALFUNCTION INDICATOR LIGHT (MIL)
- Instrument panel light, used on some models starting in 1987. The light comes on when the ECA goes into Failure Mode Effects Management (FMEM) strategy, alerting the driver that a malfunction has occurred.

Manifold Absolute Pressure Sensor:

MANIFOLD ABSOLUTE PRESSURE SENSOR (MAP) - A sensor or its signal circuit that sends a varying frequency signal to the processor for calculation of barometric pressure based on manifold vacuum and manifold pressure.
MANIFOLD CHARGE TEMPERATURE SENSOR (MCT) - See "air charge temperature sensor (ACT)."


MANIFOLD CONTROL VALVE (MCV) - A thermostatically operated valve in the exhaust manifold for varying heat to the intake manifold with respect to the engine temperature.


MANIFOLD VACUUM - Vacuum generated below the throttle plates of a carburetor. Vacuum present in the intake manifold. Manifold vacuum is high at idle and lowers as the throttle plates open.


MASS AIR FLOW METER (MAF) - A sensor that measures the mass of air flowing through the meter via a hot wire sensing element and an electronic circuit.

Microprocessor Control Unit:

MICROPROCESSOR CONTROL UNIT (MCU) - Integral part of electronically controlled feedback carburetor using TWC catalyst. Various sensors monitor mode conditions. MCU is widely used on Ford-built vehicles for the control of air/fuel ratios.
MONOLITHIC SUBSTRATE - The ceramic honeycomb structure used as a base to be coated with a metallic catalyst material for use in the converter.