i had posted previously about not knowing where a hose goes on my 91 na and i have found out thus far that its the hose that goes to the cat for the smog pump and 6 ports to work properly.. but unfortanatly i have not cat and the hose is just there.. not plugged or blocked off or anything.. and my 6 aux ports arnt working.. how do i fix this?

 

91 activates the ports electronically.
that hose is not needed for ports.

 

What is the hose for on an S5? I want to get rid of my cat and that hose/pipe is what rattles underneath the car and it's annoying.

 

That tube supplies air to the cat...since you've deleted the cat, the tube can go as well.

 

but my ports are not opening at all.. i was told s5s need the pump or it wont function right

 

Yes, the air pump is needed since that is the supply to pressurize the actuators (s5). The hose to the cat is not needed if you don't have a cat.

 

to clarify: in an S4 car the cat pipe is used to measure and use the exhaust pressure to open the aux ports. But in an S5, the cat pipe is just for emissions. it adds air to the exhaust to lower CO2 or whatever. S5 aux ports are activated by the airpump on the engine alone and it is electronically activated around 3800 rpms.

if yours aren't operating, they might just need to be lubed up. you can take them off or just try and push them back and forth to get them smooth again. also, just revving your car to 3800 rpms might not tell you if they work. I know in an S4 they will only work under load but s5 is electronic so idk. put some grease on the rods of the port actuators and go drive in first till 4500 rpms or so and then check to see if the grease has been moved. that will tell you for sure.

 

thanks alot guys.. the info is great and now i cant wait to get home and take em off to clean em.. so should i just cap the hose and leave it at that

 

you can remove that whole pipe if you want and cap it up farther if you want, yes. Keep in mind that your port activation could still be something electrical. But they do get gummed up so its worth a try to clean them and see what happens. after that if they still are not working then make sure that your air pump is working. you can look up the procedure in the FSM.