At what rpm level should the fast idle be on my Ford Focus and how long should it stay at fast idle before it gradually comes down to normal idle? Ever since the battery was change, the fast idle is around 1200 rpm but only stays at fast idle for maybe less than 2 minutes. Any recommendations for a DIY fix?

 

Vehicle year is important,but if the battery is disconnected the PCM will require a period to reset it's idle speeds This is usually done by starting the engine and not touching the accelerator pedal to allow the computer to set the speed that is programmed into the PCM. After you reconnect the battery don't touch the throttle pedal after starting the engine. The PCM will get the speeds correctly after a few minutes of running.

 

The year of my Ford Focus is 2012. Yesterday when I started for the first time that day, the outside temp was 46 degrees. I never touch the gas pedal when staring, and the rpm was 1200 as I stated in my original question. Rpm fell to 800 in less than one minute. Could there be a problem with the Idle air control valve? There where no trouble codes when it was taken for emissions testing in August of this year and the check engine light hasn't come on at all. Battery was replaced earlier this year.

 

To be clear,
If at the time the battery was disconnected and memory lost then reconnected and the vehicle started and the throttle was depressed, that was entered into memory and stays there until erased. So, no matter how many times you restart the vehicle and don;t touch the throttle , the info is already entered in the PCM and it would need to be reset and the correct speeds allowed to be set according to the programming.

 

So what I understand your suggesting, is that the battery needs to be disconnected and reconnected to reset the PCM. Doing this and not engaging the throttle will fix my fast idle problem of only being at 1200 rpm for one minute. (cold start)

thanks

 

If that is what happened, try it and see what you get.

 

I'll try that. Thanks