Owner manual

4
4-7 GM
MFI – Multi-port Fuel Injection.
MIL – Malfunction Indicator Light. Check engine light.
MIXTURE CONTROL SOLENOID – Device installed on
carburetor, that regulates the air/fuel ratio.
MLP – Manual (shift) Lever Position sensor or its circuit.
MPFI – Multi-Port Fuel Injection.
MULTI-PORT FUEL INJECTION – Individual injectors for
each cylinder mounted in intake manifold. Injectors are pulsed
in groups rather than individually.
NDS – Neutral Drive Switch.
NGS – Neutral Gear Switch or its circuit.
NON-VOLATILE MEMORY – Memory retained in block
learn cells (not affected by turning the ignition ON or OFF).
NOx – Nitrous Oxides.
NPS – Neutral Pressure Switch or its circuit.
OCT ADJ – Octane Adjust device which modifies ignition
spark.
OXYGEN SENSOR – Sensor that changes its voltage output
as exhaust gas oxygen content changes as compared to the
oxygen content of the atmosphere. The constantly changing
electrical signal is used to control fuel mixture.
PCM – Powertrain Control Module. Computer that controls
engine fuel, ignition and emission related functions.
PCV – Positive Crankcase Ventilation. System that controls
flow of crankshaft vapors into engine intake manifold where
they are burned in combustion rather then being discharged
into the atmosphere.
PFE – Pressure Feedback EGR sensor or its circuit.
PFI – Port Fuel Injection.
PORTED VACUUM SWITCH – Temperature actuated
switch that changes vacuum connections when the coolant
temperature changes.
POT – Potentiometer.
POWERTRAIN CONTROL MODULE – Same as ECM, but
also controls electronically controlled automatic transmission.
PROM – Programmable Read Only Memory.
PSPS – Power Steering Pressure Switch. Signal is used by
computer to compensate for power steering loads.
PVS – Ported Vacuum Switch.
PWM - Pulse Width Modulation.