I bought the car like this:
Stock header to a hollowed out pre-cat 1 to a junk pipe welded on all the way down split then welded to the stock mufflers.
The pipe that hooks to the cat hooks to nothing because there is no cat.

I have a S4 N/A

Are my auxiliary ports working?

Too many people say too many things, I've boiled it down to that fact that my ports open via velocity exhaust pressure, is that getting to them with this pipe set up?

 

If the pipe is not hooked up, then No.

 

How do I get them working? I've heard there's headers with an opening, is that what I need?

And will I still need my air pump or can I get take that out?

 

The split air pipe has to be hooked up to either the cat location or to a header that has a connection. From what I've heard, people have had success with both the header and something like racing beat's presilencer, but straight pipe usually will not due. I ran my car for a long while with a straight pipe that had the split air pipe welded on, and my aux ports never worked.

It seems like the setups that have a series of bends in the pickup tube are able to build up enough pressure, but the activation method is shoddy at best. You can remove the air pump if you don't need to smog the car, but there is a better option. I've posted this a few times, but tapping into the air pump, and using a solenoid and rpm switch is a much better way to activate the ports. There are a ton of posts on this if you search for it.

 

You can also check to see if they are working by putting grease on teh actuator rods and driving around. If the grease is smeared, they are working. If no grease smear, then no workie!

 

You will need to get a main cat welded up to get the actuators to move. And that split air pipe will need to be welded to it. If you look at the fuel and emissions section of the FSM there's a few pictures to see what I'm talking about. Basically, those auxiliary ports are activated by back pressure from the main cat. If there isn't one you are not generating enough back pressure to open them.

There are a few ways to mechanically operate them, but i've gotten to them to work again without going that route. See my sig.

 

A more accurate way to check actuation would be to see what PSI your actuators open, then connect a pressure guage to the split air pipe to aux port nipple and drive. Then you can see if they open in time for the 3800 rpm injector transition.

I've heard of poor actuation even with the RB midpipe specifically designed for S4 NA ports. I would guess that the problem is lack of backpressure due to lack of cat material and straight through mufflers.

You could probably tune the ports with a resitrictor plate in the cat to catback flange. Cut one out of stainless sheeting, sandwhich it between two exhaust gaskets and change the opening diameter until you get proper actuation.

 

So both the S4 and the S5 need the air pump but use it differently to open the ports?

 

the S4 doesnt use the airpump for activation of the port, only the S5 does.
The S4 only uses the back pressure from the exhaust for port activation.

 

So I could take off the airpump and AVC and that wont affect my trying to get my auxiliary port working, because I swore I read that on the S4 the airpump assists and on the S5 it does it all.