The Engine Management System (EMS) on your Ford Focus uses the Idle Air Control (IAC) valve to adjust idle speed. This valve works in combination with other electrical components. However, carbon build-up on the valve port passages affects its operation. In addition, a malfunctioning IAC valve may have a direct impact on emissions and driveability controls.
Remove the air cleaner outlet pipe form the air cleaner assembly to gain access to the IAC valve, if necessary. Use a screwdriver to remove the clamps or dislodged the pipe from the assembly, depending on your particular model.
Locate the idle air control valve attached to the throttle body of your Ford Focus. The valve is a cylindrical component, made out of aluminium, between 2 and 3 inches in length. It has an electrical connector in one end and is mounted close to the throttle body with two bolts.
Unplug the IAC valve electrical connector.
Loosen and remove the two mounting bolts using a wrench or ratchet and socket.
Raise the front of your Focus vehicle and support it on two jack stands to remove the IAC valve, if necessary. On some particular Focus models equipped with Dual Overhead Cam (DOHC) engines, it is necessary to remove the IAC valve from underneath the vehicle.
Discard the valve gasket if equipped.
Clean the valve intake ports and the throttle-mounting surface and mating ports using carburettor cleaner. Make sure to spray very small amounts of carburettor cleaner into the valve ports to keep the chemical from reaching into the electronic components. This may ruin the valve.
Wipe the valve ports clean with a swab and the throttle mating ports with a clean shop towel or rag.
Set the clean IAC valve in place along with a new valve gasket if equipped.
Start the two mounting bolts by hand and then tighten them with a wrench or ratchet and socket.
Lower the vehicle if you had to raise it to remove the IAC valve.
Plug the valve electrical connector.
Install the air cleaner outlet pipe on the air cleaner assembly, if you had to remove it.