Idle Air Control Valve (IACV) Basics brought to you by DiDonAutomotive

Did you ever wonder why your vehicle needs an Idle Air Control Valve (IACV) and how it functions? You have come to the right place to learn everything you need to know about the basics of Idle Air Control (IAC) system function!

First lets learn a bit about your vehicle’s combustion system, and more specifically, the air delivery portion of the combustion system. The following focuses on a naturally aspirated gasoline internal combustion engine.

Air passes through the inlet of your air box and then through the air filter of your air box – at this point your engine now has “clean air”. The clean air will then pass through a duct system to get to the throttle body. As the air is flowing through the duct system, the air’s state will either be measured by a Mass Air Flow Sensor (MAFS) or by a pressure sensor (or both in some cases).
– If the air flows through a Mass Air Flow Sensor (MAFS), the mass air flow delivered to your engine is measured by the velocity in conjunction with temperature / pressure estimation.
– If the air’s state is measured by a pressure sensor only in the post-air box duct system, then there will exist an additional pressure sensor in the intake manifold which then allows for a pressure drop calculation – the pressure drop in conjunction with temperature / pressure estimation allows for estimation of mass air flow. The two pressure sensor setup is commonly referred to as a “speed density” calculation.

As the air exits the duct system, it enters the throttle body which can be an electronic throttle body or a mechanically operated throttle body (whether it is eletronic or mechanical, your vehicle will generally have a output signal of throttle position back to the Engine Control Module (ECM)). The throttle blade of the throttle body is the engine’s primary actuator for metering air into the engine, especially during idle operation. The blade will rotate from almost closed (0.5 – 4% open) to full open (Wide Open Throttle, WOT) during engine operation. In this discussion, we will focus on idle operation as it pertains to the Idle Air Control (IAC) system.

Based on the throttle blade rotation within the throttle body existing as the primary actuator to meter air flow to the engine, the accuracy of its rotation would then need to be “Very Good”. I do not like using terms like “Very Good” but we will use it as a relative term for subjective determination within this discussion. The accuracy of throttle blade rotation was not “Very Good” (not good enough) during the late 1980’s to early 2000’s and did not allow many vehicles to pass ever more stringent emissions requirements. The throttle body’s inacccuracy drove the need for an addtional actuator to meter air flow into the engine – the Idle Air Control Valve (IACV) filled that need for many vehicles.

In general and relative to this discussion, the Idle Air Control (IAC) system’s actuators comprise of the throttle body/blade-rotation and the Idle Air Control Valve (IACV). Now, we will focus on the Idle Air Control Valve (IACV) portion of the system. The Idle Air Control Valve (IACV) is an actuator externally mounted to a bypass system integrated to the throttle body which allows air to bypass the throttle blade and directly enter the intake manifold. The bypass is generally a small air flow path which has been integrated to the side of the throttle body with the flow being metered by the Idle Air Control Valve (IACV). The Idle Air Control Valve (IACV) contains a type of valve which is linearly actuated against a hole in the bypass which results in the metering of air flow.

There are various types of Idle Air Control Valves (IACV) but the most common two are solenoid actuated and DC stepper motor actuated.

Please take a look at the diagrams and video for more information!!!

See the DiDonAutomotive “Homepage” to search for your vehicle’s Idle Air Control Valve (IACV).
See the “Does your vehicle have a Check Engine Light? THIS IS A STEP-BY-STEP PROCESS TO READING CODES” for support in how to read your vehicle’s Diagnostic Trouble Codes

DiDonAutomotive Idle Air Control Valves are here to support all of your vehicle maintenance needs. The following are just some of the Idle Air Control Valves offered by DiDonAutomotive which may be a likely fix for your Jeep, Dodge, Chrysler, Plymouth or Eagle vehicle,
DiDonAutomotive Idle Air Control Valve (Jeep Dodge OEM PN 4874373, 4874373AB, 53030821)
DiDonAutomotive Idle Air Control Valve (Jeep Dodge OEM PN 53030840, 53030840AC)
DiDonAutomotive Idle Air Control Valve (Jeep Dodge Chrysler OEM PN 4591611, 4591611AA, 4591611AD)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge Plymouth OEM PN 4861164, 4861164AA, 4861164AB)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge Plymouth OEM PN 4861099, 4861099AA, 4861099AB)
DiDonAutomotive Idle Air Control Valve (Jeep Dodge OEM PN 53030657)
DiDonAutomotive Idle Air Control Valve (Dodge OEM PN 53032067, 53032067AA)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge Plymouth OEM PN 4861035, 4861035AC, 4861035AE)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge OEM PN 48610356)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge Plymouth OEM PN 5014285, 5014285AA)
DiDonAutomotive Idle Air Control Valve (Chrysler Dodge Plymouth Eagle OEM PN 4861083, 4861083AB, 4861083AC)