Increase Decrease Engine Idle Speed RPM If your car idles low or high and you need to adjust the idle speed by increasing or decreasing the rpms we will show you how to do that. Modern Watching the tachometer shows an idle speed around 500 to 900 RPM. The engine's idle speed also changes, based on outside conditions. A computer is adjusting the idle speed, based on complex calculations. How do we adjust an engine's idle speed? In the past, adjusting an engine's idle speed was easy. Manufactures have removed these How to adjust idle speed in car engine. Years 2000 to 2015. How to adjust idle speed in car engine. Years 2000 to 2015. Step 1: Get ready to fine-tune your idle. After your Ford F150's engine has been running for a few minutes, shut it off. Turn the ignition key to the "off" position. Do not remove the key from the ignition switch. Step 2: Determine the location of the idle adjustment screws. With a wrench, disconnect your vehicle's negative battery cable. 4ofaL.

how do i adjust idle speed