Have a hose pipe that I believe leads from the Air Control Check Valve, but I don't know what it would have run to. When I got the car the air pump was already off and hoses where capped off with lug nuts .

The line coming off the AC/CV is the one circled with my mad tyte Photoshop skillz








I'm trying to figure out where I can/should hook that up to, or it would be ok left open, or I should just cap it somehow. I do have the air pump, but as is, it's sitting in the trunk at the moment.

 

Really need some help with this. I've been searching the forum and FSM and my Haynes book, but that pipe isn't listed anywhere. I thought maybe it connected to the Air Pump, but since it's blowing out air, I doubt it does. The car's and S5 by the way. If anyone can help it'd be greatly appreciated.

P.S. The car seems to smell like it's running a bit richer with the pipe uncapped.

 

If it's the hose coming off the side of the ACV, then it's the dump hose and it runs to the right front fender where the washer bottle is. There is a silencer there.

If that hose is constantly blowing air when the engine is fully warmed up, then the ACV is not working right and or the switching and relief solenoids are not connected up right.

A properly working ACV sends ALL the air from the airpump to holes right at the exhaust diffusers (internal to the rotor housings) where the air mixes with the exhaust gas coming out of the rotors. This is prior to the 02 sensor.

Why mention *pror* to the 02 sensor? Easy. If you have a narrow or wideband 02 sensor or even if your monotoring the 02 signal with a digital meter, you can see if the ACV is or is not working right. If you look at the gauge/meter at idle and write down that figure, and then go pull the Relief Solenoids plug off (on a non turbo) or the Switching solenoid plug off on a Turbo car, the number on the meter/gauge should go richer once you do that. IF that happens, most likely the ACV is functioning right. If the number does not significantly change, then the signal to the ACV from the Relief and Switching solenoid is not there and or the ACV's internal diaphrams are kaput.

The Split Air Pipe that numbheads are so hot on,on this forum, is not that large a player. If you do a little searching you'll find that once you've drive the car at a steady pace for approx 120 seconds give or take, the air to the split air pipe *ain't squat* especially on a turbo since now the air is being dumped into the silencer in the right front fender .

The two solenoids on the ACV are at best bit players ane frankly are insignificant. The Split Air solenoid only opens in fifth gear and the Port airs hole is tiny when open. Neither are players in emissions testing.

One of the MAJOR functions of a narrow TPS is to activate the switching and relief solenoids. Those two solenoids control the ACV. No control signal to the ACV equals all the airpump air being dumped into the right front fender where it does no good.

I KNOW there is a picture in the FSM of the hose and silencer and KNOW there is a procedure for testing the ACV to see if it's working.

Page F1-3 of the series five FSM shows the silencer/pipe/hose/acv/airpump stuff.

 

Thanks for the detailed explanation but unfortunately, it's not the pipe that feeds the silencer. In the second and third pictures, it's the pipe that runs away from the right fender, towards the alternator. The pipe itself is briefly pictured in both the Haynes and FSM, but there is no reference to it, nor do the pictures show what it would connect to.

A clear picture from the FSM:


Circled part is the pipe I'm lost about:



By the way, since I don't have the air silencer, never came with the car, would it be safe to run the pipe that would lead to it open instead of having it plugged with yet another lug nut?

EDIT- Having gone through my Haynes manual again. I have figured it out, and that pipe does indeed lead to the back of the Air Pump.
The red line shows the Pipe and it's route:


So my question now is, why would it be blowing out air when, from my understanding, the Air pump would be pushing air through it? Essentially, the ACV is blowing one way, while the Air Pump is blowing the other? And since I don't have the Air Pump on at the moment, and the parts stores are close, should I just cap that line for now or is it safe to run open?

P.S. if I'm wrong about how the air pump works please let me know. Thanks.

 

Alright I did some more searching and re-read your post Hailers. As I understand it, the Air Pump, which is connect to the TID, feeds air to the ACV through the very pipe that started this thread, where it mixes with exhaust gases and out it goes through the exhaust. So my only real question is whether or not I should unplug the line that would have been feeding the silencer, if I had the silencer. Meaning it would be venting to open atmosphere.