Recently I've been having a very rough idle while the car is using its AC. The check engine light popped up a few days ago, but I've been too busy to fix it until today.

I went to Autozone and they ran a diagnostic or w/e, and it came back with this:

Troubleshooting P0506
OEM Brand: Domestic

Definition
IAC circuit condition or idle speed higher/lower than expected.

The ECM has detected that the IAC counts are higher or lower than expected, the engine speed is not in its expected range.

Probable Cause:
1) Vacuum Leak on Engine
2) Dirty Throttle Body
3) IAC motor defective
4) Poor electrical connection to the IAC valve.

I bought some TB and MAF cleaner, which I might be able to get on tonight. I'm also going to remount my CAI in case it got bumped or something(It was fine before I had my car inspected) and hopefully that will clear everything up.

Also, where is the IAC, neither me nor the autozone dude could even see it? Would it be integrated into the TB or something?

Any of you guys have any problems with a rough idle or any input?

 

Is it only when the ac is on? That's how my car is when the ac is running, the idle fluctuates

 

mine does the same rough idle and makes noise too!

 

I would think it could be a dirty throttle body... Had the same crap on my trailblazer the car would not idle right with the AC running. I didnt think it could be the TB but I pulled it and cleaned it and also cleaned the MAF. Problem fixed... So am sure it could be the same issue on a stang. Mine started after the computer was reset when my battery was disconnected.

 

http://www.ford-trucks.com/tsb/fullt...hp?tsb=08-18-2

 

Well, just cleaned the TB and MAF. The whole intake and filter are covered with brown dust. I can't believe how dirty everything has gotten over the last couple weeks. A few months ago everything was in much better shape when I got inspected. Gotta love the Lubbock dust storms.

I'm letting everything dry, as well as having the battery set for a few hours and will re-upload a tune. Also, my filter was dirty as hell too, and I just cleaned it a few thousand miles ago. Errrr

TB:

All of the black stuff, and what looks like water stains came right off. Behind the butterflies lies another layer of gunk. Disgusting.
MAF:


MAF wasn't in as bad of condition, but there was still a ton of dust around the seal. The screws were fully fastened, but a little bit of dust was able to squeeze by. I'll be getting some type of removable seal/sealant to make sure it stays clean.