91FORD13 A

ACCELERATOR SWITCH (Courier) - Located on accelerator pedal. Activates anti-afterburn valve to reduce rich mixture on deceleration.

Normally Closed Air Bypass Valve:

AIR BYPASS VALVE - A valve in the air pump system. At high engine vacuum, it vents pressurized air from the air pump to the atmosphere in order to prevent backfiring. At other times it sends air to the exhaust manifold; on cars with a three-way catalyst, it sends air only to the oxidation catalyst when the engine warms up. Also known as the "anti-backfire valve" or "diverter valve."

AIRBLEED CONTROL VALVE (ABCV) - Device used on some feedback carburetors which bleeds air into the carburetor to attain the most efficient air/fuel ratio. Controlled by the ECA.

AIR CHARGE TEMPERATURE SENSOR (ACT) - Air charge temperature sensor or its signal line. Thermistor sensor can be located in intake manifold (EFI Systems) or air cleaner. Responsible for inputting the ECA the temperature of air stream in the air filter or intake manifold. If air is cold, signals choke to let off slowly. Alters engine speed after choke is off, and below a certain temperature dumps thermactor air for catalyst protection. This type of sensor decreases its electrical resistance as its temperature rises.

Air Cleaner Bi-metal Sensor:

AIR CLEANER BI-METAL SENSOR (A/CL BIMET) - Senses the temperature of incoming fresh air. Bleeds off vacuum when air cleaner is warm.

AIR CLEANER DUCT AND VALVE VACUUM MOTOR (A/CL DV) - Opens and closes the air cleaner duct to provide heated or unheated air to the engine dependent upon the temperature of the incoming air.

AIR CONTROL VALVE (ACV) - A vacuum controlled valve in the thermactor system which diverts air pump air to either the upstream (exhaust manifold) or downstream (underbody catalyst) air injection points as required.

AIR PUMP - A device to produce a flow of air at higher than atmospheric pressure. Normally referred to as a thermactor air supply pump.

Altitude Compensation System:

ALTITUDE COMPENSATION SYSTEM - An altitude Barometric Switch and Solenoid used to provide better driveability over 4,000 feet above sea level.
ANTI-AFTERBURN VALVE (Courier) - Prevents abnormal combustion in the exhaust manifold by increasing fresh air in the intake manifold on sudden deceleration. This tends to reduce vacuum and fuel flow.

Anti-Backfire Valve:

ANTI-BACKFIRE VALVE (Anti-BFV) - Often called a gulp valve, the anti-backfire valve is located downstream from the air bypass valve. Its purpose is to divert a portion of the thermactor air to the intake manifold when it is triggered by intake manifold vacuum on deceleration. The valve operates only during periods of sudden decrease in intake manifold pressure.
ASPIRATOR - A device placed in the airstream at the outlet of the turbocharger or in some cases the thermactor. The speed of the air going through the aspirator creates a venturi vacuum that is used to operate the speed control system during periods when the engine is under heavy load.

AUTOMOTIVE EMISSIONS - Gaseous and particulate compounds that are emitted from a car's crankcase, exhaust, carburetor and fuel tank (hydrocarbons, nitrogen oxide and carbon monoxide).