Sometimes the internal combustion engine in a Honda Civic can begin to function improperly. This will cause the car to sputter at idle, resulting in a rough ride or, in some cases, frequent stalling. In order to alleviate this, you have the option of adjusting the cold idle, smoothing out the engine and improving ride quality. Changing the idle speed can be done by manipulating the amount of air and fuel that enters the combustion chamber by adjusting a small screw.
Open the hood. Use the hood support rod to keep the hood securely open.
Locate the idle adjustment screw. It will be underneath the air box located in the center of the engine. You do not need to remove the air box as the screw is accessible from the side.
Turn the screw using a Phillips-head screwdriver. Turning it clockwise will raise the idle speed, turning it counterclockwise will lower it.
Start the car and check to see if the Civic is idling where you want it to. If not, turn off the car and repeat the process.
