Hey guys, I posted this in my build thread, but in hopes of attracting more of an audience i'll throw it here as well.

I'm not sure if this has been posted before, but I personally did not find it when i was searching.

Anyway, I've seen a few threats asking about the BAC, removal/reinstall, etc. Some about how to clean it. Since i'm a firm believer that the BAC valve serves a great purpose, and taking it off just causes more headache than its worth (if it isn't broke, don't fix it, imho) I'm posting this to help anyone else that may be trying to clean their BAC if its stuck/sticking.

I just tried this today, so anyone with more experience than I, feel free to chime in and give your thoughts. I'm trying to do help here, not harm.

This may work for S4 guys, but I'm not entirely sure, its been eight years since i've owned an S4.

If you look at the bottom side of the intake piping, you will see two bungs with hoses attached, one goes to the BAC, this is the one you want.

Unplug this hose from the intake pipe, not the bac valve.

cap the bung on the intake pipe to prevent the car from taking in air that is not accounted for.

you will now have this:





BAC valve hose disconnected from intake pipe. You can see the other end of the hose fixed onto the BAC valve itself.

At this point I fired the engine up, (it may want to die on you, mine did) and worked the throttle up and down as I sprayed the inside of the hose with carb cleaner. The car will sputter and shake a bit as you do this, as well as smoke. Think of it as a mild seafoam treatment. I then let the engine choke on the carb cleaner and stall out.

I waited a few minutes, and re installed the hose onto the bung on the intake pipe, fired her up, and let her burn off the remaining carb cleaner.

Anyone have any feedback as to if this is an effective way to clean the BAC?

 

it is easy, so you're ahead there.

 

Not sure how I'd feel about carb clean eating any seals or the hose...