- I -

Idle Air Bleed Valve

A device used to control the amount of airflow into the idle fuel mixture prior entering the carburetor idle system (M/C) solenoid on.

Idle Air-control Valve

A General Motors 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.

Idle Circuit

The system within a carburetor that meters fuel when the engine is running at low rpm.

Idle Compensator

A term used for engine-idle compensator or hot-idle compensator.

Idle Limiter

A device that controls the maximum richness of the idle air/fuel mixture in the carburetor.

Idle Load Compensator

(ILC) This 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.

Idle Mixture

The air/fuel mixture supplied to the engine while idling.

Idle Port

An opening into the carburetor throttle body through which the idle system discharges fuel.

Idle Relearn

The routine of the computer that resets idle requirements when a disconnected battery has been reconnected.

Idle Speed

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.

Idle Speed Control Motor

Regulates the throttle valve position and is controlled by the computer.

Idle System

The passages of a carburetor though which fuel is fed when the engine is idling.

Idle Vent

An opening in an enclosed chamber through which air can pass under idle conditions.

Idle-limiter Cap

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.

Idle-mixture Adjustment

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.

Idle-mixture Screw

A screw on the carburetor used to adjust engine-idle speed.

Idle-speed Adjustment

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.

Idle-stop Solenoid

An 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.

Idler Arm

A pivoting component that supports the right side of the steering relay rod in much the same manner as the pitman arm supports the left side.

Idler Eccentric

A device used in a belt-drive system using the idler pulley as a means of tightening the belt.