Sprt Trk idling rough with A/C on

2001 Sport Trac idles rough when the A/C is on... sometimes stalling. I recently replaced the Idle Air Control Valve due to a check engine light (was actually caused by a vacuum hose leak). Fixed that but the rough idle continues when the air is on. Stealership tells me my computer may need flashed..!?! Whatever. Help, please.

the "stealership" is your best bet. as a dealership employee I can tell you there is a pcm update to fix this concern. and thanx again for the attitude. those of us who are honest at dealers love YOU guys.

Welcome to the forum!

If you have access to a professional-grade scan tool, get into the component parameters and monitor the misfire PIDs for each cylinder. Maybe you have a coil or two that is failing under load. Does the roughness only occur at idle, or when driving as well?

Also, have you ever cleaned the Mass Air Flow (MAF) sensor? Do you have any modifications to the engine of your Sport Trac (such as a K&N or similar air filter)? Do you regularly use fuel injector cleaner?

-Rod

shorod, I do not have my own scan tool but the roughness only occurs at idle, with the a/c on. If I turn the a/c off, the idle is fine. When it’s in gear with the a/c on and the compressor kicks on is normally when the stalling occurs, but not all the time.

I do not have any aftermarket components on my truck and I have, on occasion used injection cleaner but nothing on a regular basis. I’ve been reluctant to clean my MAF due to some threads I've read that say it can leave a residue which can be just as bad on the filament as the original dirt. Maybe I’m wrong and should try cleaning it. Let me know your opinion. Who knows maybe I have a bad IAC out of the box.

In regards to rivguy’s comments. Sorry if I offended you. You know as well as I do that there are honest and dishonest in all walks of life. I’ve spent enough time around dealerships to know that they aren’t always the best option available. Unfortunately, sometimes they are your only choice. Maybe I’ve just been burned too many times lately to have the level of respect I once did. However, because you’re basically echoing what I they have told me, as far as the pcm update is concerned, I may end up taking it to them for repair.

If there’s any other ideas, please let me know.

Thanks for all your help.

as for the maf cleaning - use a high grade cleaner and you shouldn't have any problems - I clean em all the time - for the concern you are having the update is prolly your best option. I could get you the message # or even a copy if you would like to verify the concern against fords description of know cause. and that it applies to your peticular vehicle (eninge, options and calibrations do make a diff.) if you would like me to run your vin e-mail it at [email protected] with a message as to what I'm looking for since I get many numbers each day.