Querky AC / idle question!
 

When idling with the air conditioning off, the idle is rough, and sometimes seems as if its missing here and there, turn on the A/C, and the idle is smooth with no missing! I've looked through the threads but can only find things with the idle getting rough and even stalling when the a/c is turned on. Any help would be appreciated!

When was the throttle body last cleaned? Idle is maintained by controlling air flow on the intake. With the a/c on, more air is introduced by the idle air control motor. With a/c off, more of the idle control is dependant on the throttle body, which builds up deposits over time at the butterfly valve. These deposits ruin the idle on an otherwise good-running engine. A good cleaning with solvent and a toothbrush can perk up the idle.

You didn't mention which vehicle you have or how old it is. Try looking for vacuum leaks in addition to cleaning the throttle body.

Good question.
 

I've had the car for two years, and i haven't had it cleaned, i have all the service papers from the owner before me, and i dont see any cleaning on those, i'll give it a try, thanks!

Hi Kestas,

Sorry! 1985 500 SEC. Thanks!