Glossary “idle system” Definition:
The passages of a carburetor though which fuel is fed when the engine is idling.

Glossary “idle vacuum valve” Definition:
This device may be used in conjunction with other vacuum controls to dump thermactor air during extended periods of idle, to protect the catalyst.

Glossary “idle vent” Definition:
An opening in an enclosed chamber through which air can pass under idle conditions.

Glossary “idle speed control solenoid” Definition:
Device mounted on the throttle body which controls the amount of bypass air to maintain correct idle speed as engine operating conditions change.

Glossary “idle stop solenoid” Definition:
Electromagnetic device mounted on the carburetor linkage that maintains the proper throttle opening for specified idle speed while the ignition is on, but allows the throttle to close further when the ignition is switched off, reducing the amount of air that can enter the engine and the likelihood of dieseling.

Glossary “idle switch” Definition:
A switch sensor circuit to the PCM to detect whether or not the throttle is closed.

Glossary “idle mixture screw” Definition:
A screw on the carburetor used to adjust engine-idle speed.

Glossary “idle port” Definition:
Opening into the carburetor throttle body through which the idle system discharges fuel.

Glossary “idle relearn” Definition:
The routine of the computer that resets idle requirements when a disconnected battery has been reconnected.

Glossary “idle speed” Definition:
The speed at which an engine idles in revolutions per minute (rpm), usually between 600 and 850 rpm. The idle speed is specified on the under-hood emissions decal.

Glossary “idle speed adjustment” Definition:
The idle speed on carbureted engines without computer idle-speed control is set by turning a screw that opens or closes the throttle plates. On fuel-injected engines without computer idle-speed control, idle speed is set by turning an idle-air bypass screw that allows air to bypass the throttle plates. Idle speed is not adjustable on engines with computer idle-speed control.

Glossary “Idle Speed Control Motor (ISCM)” Definition:
Regulates the throttle valve position and is controlled by the computer

Glossary “idle load compensator (ILC)” Definition:
Device is used to control throttle angle during long deceleration such as coasting down a long grade and extends the WOT position to prevent engine stalls.

Glossary “idle mixture” Definition:
The air/fuel mixture supplied to the engine while idling.

Glossary “idle mixture adjustment” Definition:
An adjustment made on carbureted engines by removing the antitampering plugs and turning the idle-mixture screws until the proper idle mixture is achieved. Setting the idle mixture on an emissions-controlled engine may require monitoring exhaust CO or using a special procedure called propane enrichment.

Glossary “idle limiter cap” Definition:
A plastic device pressed over a carburetor’s idle-mixture screw that limits the amount of adjustment during service to help eliminate excessive air pollution that is caused if the mixture is too rich.

Glossary “idle air bleed valve” Definition:
Device used to control the amount of airflow into the idle fuel mixture prior entering the carburetor idle system (M/C) solenoid on

Glossary “idle air-control valve” Definition:
An electrically operated valve that, on commands from the engine-control computer, varies the size of an air passage that bypasses the throttle plate of an electronic fuel-injection system, thus controlling idle speed.

Glossary “idle circuit” Definition:
System within a carburetor that meters fuel when the engine is running at low rpm.

Glossary “idle compensator” Definition:
Term used for engine-idle compensator or hot-idle compensator.