Alright, so i was working on my car and found a tube that connects to something and then doesnt go anywhere. It has a clamp on the end that goes nowhere so that makes me think it is supposed to connect to something else. Anyone have a guess? Here are some pictures of the tube and where it comes from (these were the best I could get). Thx for any help or info anyone might have

 

I take it you have a s4 NA? That is the hose that supplies the backpressure necessary to open your 5th/6th ports. It should be connected, but seeing as you have a header it explains wht it isn't connected.

No biggie, just your 5th/6th ports aren't opening.

 

yes i have an s4 n/a....

so thats what opens the 5th and 6th ports? i was told with a header and cat you'd still have enough back pressure to open them up, so is that supposed to be connected to something? this is very helpful if this is the reason that my aux ports arent opening, which i found out recently. If this no longer connects to anything, how do i make sure my ports will open?

 

Yep, that tube is for the aux ports, from the cat airpump line.

Either hook the air pump line back up, or drill a small hole into the relief line of the ACV (between the ACV and the air pump muffler just under the AFM on the frame) and stick the small disconnected line into that relief line. That relief line will have about 2 psi at 3800-4000 RPM between the air pump muffler and the ACV.

 

Where is the airpump line? I actually dont know where the airpump is, i know my cat is hooked up to the split air selenoid valve (thats what the FSM said so thats what i had the exhaust shop do)... Is there an actual line at the air pump for that to hook into then?

 

there are a few threads covering this topic, one of the good fixes for this is wiring up an rpm switch and a little airpump to electronically activate the 5th/6th ports opening up.

For a short term fix you could always wire them open, meaning that you do what it says, wire them to be opem. The downside is that they will be open all hte time, and you will lose a little low end power.

 

ohh, didnt know about that one Icemark, good tip.

 

The air pump line I was refering too, is the hard line that runs from next to the car to that valve in your picture. It is offically called the split air pipe. On the split air pipe there is a little T that your disconnected line hooks onto.

 

yeah, the only draw back is that the line has about 1 psi at 3000 rpm, so you can't do that set up on a S5 which uses lower air pressure to activate the aux valves.

But on a S4, the aux valves don't start opening until about 1.5 PSI and fully open at 1.8/ 2.0 PSI.

 

Well now you've got my curiosity up. I can see in all the pictures that you still have the split air pipe on the back of the manifold. The thing with a mushroom checkvalve and a red wire being held on with a ziptie. So just where in the wide workd of sports is the split air pipe connected to on its other end???? Going to the Cat, right???? If that's so there's more to this than meets the eye.

And FYI from a post above: the airpump does nothing at all for a series four auxillary port actuator. Nil.

 

yep, my method was only if your were not using the signal for the split air pipe and didn't have an RPM switch and vac switch.

 

Wait, I'm confused about something. I thought the cat was supposed to be hooked up to the split air selenoid valve (FSM), which i am almost 100% sure it is since i gave the diagram to the shop that installed my new exhaust (this was with the mystery tube already unhooked and a header in there, the last owner had the header going to a presilencer and hks exhaust) so heres the pic again, is that the tube its supposed to be hooked into? if so, how?

 

yes that pipe in the picture above (circled in red) is hooked up to the cat

 

Well, the split air pipe should have a tiny nipple on it just below the mushroom checkvalve. Maybe its a foot below. THAT should have a rubber hose the size held in your hand and it should go to the pipe near the rear auxillary actuator. BUT I see in the picture that there is already a hose attached to it. It that the hose that is in your hand? Lunch time, later.

 

Should be a nipple in the split air pipe, just below the yellow arrow


That is where that vac line normally goes

 

yes the hose in my hand is the one that is connected to the nipple behind the aux ports you're refering to...


so that means there's supposed to be a nipple on the line hooked up to the split air selenoid valve? if not, icemark is this what you were refering to that i drill into?

 

o i c.... so if there isnt one there, i just drill into it and put the hose in there or what?

 

No, if the nipple is not there (as maybe you used a Turbo Split air pipe?) then you should move the line to tap into the ACV relief line.

That is the black rubber line coming off the bottom of the AVC, and it runs over to the air pump muffler on the passengers frame rail.

 

Yah i just went and checked and there is no nipple on it to hook that line up to. But i was thinking, drilling a hole and just putting the tube in there doesnt seem like it would suck air to open the ports, but maybe im wrong

 

I'll see if I have a old picture of what I mean on my laptop... and post it later.

 

the exhaust shop made that split air pipe.

now as for tapping into the acv relief line, you said drill a hole and put the tube in there? how is that gonna work? or do i drill and put a nipple on somehow?

 

I am on my desktop system... I'll see if I have a old picture of what I mean on my laptop... and post it later.

What I have done before is to drill (like a 1/8 inch hole) into the rubber relief line, stick a 1/4" to 1/8" inch plastic vac line adapter (any auto parts store should have one) into the 1/8 inch hole you drilled.

The 1/4" side would be the side I would stick into the 1/8 inch hole, as you want the tap to be very tight and not leak or pull out easily.

Then you would take the aux port line and hook it onto the 1/8 inch side of the 1/4 to 1/8 inch vac line adapter.

 

Ok, thx for all your help

 

The nice thing about the air relief line tap for the aux ports, is that the exhaust back pressure no longer is a factor in opening the S4 aux ports.

 

does it for sure supply enough pressure to open them fully still?