S13 PAIR Valve Control - What does it do?

[wannawangan]

I have a 93 240sx w/ a KA24DE. During installation of a custom air filter system, I've noticed a tube branching away from the intake coupling (located between the stock air filter box and the MAFS) and towards a ridged box, close to the driver side shock tower. If you reference the 240SX (S13) FSM, under Engine and Emission Control, you will see the diagram titled ECCS Component Parts Location. The box I am referring to is located between the PAIR valve and PAIRC-solenoid valve.

Would I be able to just put a breather filter w/o experiencing any problems w/ performance?

Based on the description of the PAIRS system, it is said to provide secondary air to the exhaust manifold. I am not clear what this provides as far as emissions and performance is concerned. In other words...

What does it do?

[TheOne]

its supposed to give air to the exhaust(and i think to heatup the cat faster?) so it starts acting faster i think, i put a breather in that line, but most people would either remove it or clean it, the S14 doesn't have 1 though so i'll probably remove mine later.

[bcar240]

ya, that is also called the AIV sometimes. It is an emssions thing that doesn't do much after a few years and was removed from later models so I hear. I removed mine completely, ridged box and all and its sitting in my garage. Just have to plug up that hole in the intake, I just epoxied a piece of metal in it. If you remove the whole thing there are a couple vacuum lines and a tube to the exhaust manifold to plug, but no biggie.

[wannawangan]

ya, that is also called the AIV sometimes. It is an emssions thing that doesn't do much after a few years and was removed from later models so I hear.

I also noticed that the S14's (95+) no longer had them based on looking a various engine bays of both NA KA's and Turbo'd. By the looks of my 240, when I complete my turbo project, all those components will have to go. I will need the clearance for a top mount set up.

[wannawangan]

What size breather did you use? I picked one up from Walmart today w/o 1st taking the measurement of the PAIRS valve/AIV. The valve diameter measures approx 1/2" compared to the roughly 1/8" on the Walmart/APC breather I got. I am going to route the breather a la CAI to see if it would do anything.