It will eventually learn it on its own but it may take over a week of driving during which time you will experience high and low idle speeds and possibly rough idle heres the throttle body relearn procedure 1 start the engine and let it idle in park for 3 minutes during that period the idle may be higher idle than normal. Poor idle after a gm throttle body replacement install we show you how to perform the pcm relearn procedure so your vehicle runs normallyinstructions1 st. Ford throttle body relearn procedure how to do a ford throttle body relearn procedure if youve replaced your ford electronic throttle body or youve disconnected the battery you must do a ford throttle body relearn to establish a new baseline idle starting in early 2000s many car makers including ford started installing fly by wire . Procedure 4 throttle idle learn description the engine control module ecm learns the idle position of the throttle plate to ensure the cor rect idle anytime the throttle body is cleaned or replaced the ecm must learn the new throttle position the idle may be unstable or a dtc may set if the throttle position is not learned