okay i'm lookin into getting a test pipe fot my '90 TII, and i know that the line from the air pump has to run into the cat to supply more oxygen. Is that the only purpose of the air pump or does it have somethin to do with the intake also?
...can someone please give me a straight answer cuz i searched the forums, but everybody just argues and makes it as confusing as humanly possible. thanks

...and can i block of that hose to the cat if im puttin in a test pipe anyhow?

 

I think it might be just for emissions but I'm not positive, I don't know TIIs very well

 

It puts air into the cats to burn excess fuel, if you dont use a air pump the cats will get clogged and not work efficiently

 

It pumps oxygene (air) into your cat so it lights off correctly. As someone said, without it your cat will clog and fail quickly. And on 89-91 cars it also provides pressure so your VDI (Variable Dynamic Intake) valve works along with your 5th and 6th ports. You better come up with a way of making those things still work if you remove your cat. SEARCH for VDI and 5th and 6th ports for s5 cars.

~Mike.........

 

no auxilliary ports he said he has a TII....

 

Theres no need for your airpump then, rip it out!! Unless..... it needs to be there for a visual inspection for emissions. You really dont even need to plug that line at all.

~Mike........

 

these 5th and 6th ports you speak of are exhaust ports correct? so when you tromp on the gas the air pump pushes oxygen into those ports?

 

oh, so i don't have those auxillary ports then... but wouldn't i still need it for the Variable dynamic intake? kinda confused as to what that is

 

you have a tii so you dont need to worry or know about the 5th and 6th ports bc you dont have any and they're intake related not exhaust.

 

if you have a T2 just yank it out but get a yahoo belt or a dual alt pulley.if you don't might as well say goodbye to your water pump since the belt will beed to be tensioned too high to stop the alt belt from slipping.

if it's a N/A prepare to loose top end power.

 

No, they are intake ports and the air pump provides the pressure to open them but does not inject any extra air into the intake itself.

 

soo if you run a straight pipe you pretty much dont need to air pump as in not having a cat it would be useless ?

 

The air pump air is directed by the ACV (air control valve) which has a series of solenoid valves that direct the air. The air pump puts air in the cat to increase efficiency and cat life, but it also injects air right at the exhaust port to lean out your idle mixture (so it doesn't smell like fuel and burn your eyes), and finally it injects air into the intake manifold (anti afterburn valve) to reduce backfiring and popping on deceleration.

Most of the air pump's purpose on a T2 is for emissions and daily-driver stuff. normal car owners don't want their car backfiring and smelling like fuel.

 

Half right. Air is injected into the exhaust ports for the same reasons it's injected into the cat, the different injection point is for different loads and engine speeds. It has nothing to do with altering the idle mixture, which wouldn't happen anyway since the mixture has already combusted.

 

I don't think he meant that it leans out your intake but rather your exhaust, fresh air is pumped into the exhaust in order to tip the balance from nasty air to clear air, doesn't really make it any less polluted just diluted to you can't smell it..
kinda like adding water to ****... still drinkin ****, just doesn't taste as bad...
(so i have been told... LOL)

 

I think the VDI is also non-turbo only. If you don't have a cat then there's no need for the air pump. You can't burn the excess fuel very fast without a cat.

 

Injects air into the Exhaust ports at idle to create a afr closer to 14.7 than what would be seen if you didn't inject air to the exhaust ports. This air is referred to as PORT air in the FSM/Training manual.

The ACV puts out Port air at idle and under other loads while driving.

Catalytic converters are most efficient seeing exhaust afr of approx 14.7, prior to the exhaust entering the converter.

Air going to the catalytic conveter thru the split air pipe is referred to as Split Air in the FSM/Training manual. Air going to the split air pipe is usually only for approx 120 seconds after a load has been on the engine. Then the ACV opens the Relief poppet and the airpump air is dumped overboard into the right fenders silencer.

See pages 4-57 thru 4-59 of the free, online, training manual that is availabe on this site for a download.

The NZ's explanation was more comprehensive than mine. I'm just out to dispell the bs about how air is sent to the converter thur the split air pipe to make the converter work as a *converter* of exhaust gases. It's bs.