Well I got to go to a referee. And Im putting back on my stock exhaust system and only god knows why the pipe for the Split Air is not there.

So Now my question is can I pass smog without the split Air Pipe. I still have the air pump and all my smog equipment. Should I just leave the split Air pipe open or plug it up with a bolt or something?

 

Next to impossible.

On modern Monolithic cats, They really are two stages, for the 2nd stage to work correctly it needs O2 and Nitrogen injected in.

Just hook up a hunk of metal tubing with a couple of pieces of high temp flexible hose. Aluminum/metal bendable tubing is available at most home improvement stores.

 

if you're going to the referee then he's gonna look for it, as its part of the visual.

if you're just smogging the car, it doesnt use the split air pipe under the test conditions, so you dont need it. if there is air pump air going thru the split air pipe during the test, theres something wrong with the ACV/TPS...

 

I'm sorry if I brought this back from 2 years ago, but the posts so far have answered 90% of my inquiry.

I have a S5 and I need the split air pipe for smog:

I lost the stock split air pipe with the check valve. I'm short on time and money at the moment and making one as Icemark mentioned is my only option. I've searched and read other threads and most say just use a rubber heater hose. Though I like Icemarks suggestion better, I really just need a temporary fix for the smog test. I will replace it with a stock one later.

So my my question is should I go with Icemarks or just run a rubber heater hose? I have to do some driving to heat up the cat and I don't want anything melting or falling off.

What should I do? It will be from the air pump to Cat directly.

 

Yes, you can hook it up directly to the cat.
Here's some reading:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/emission-testing-texas-style-465422/

 

You can use silicone hose rather than the heater hose. Silicone hose won't melt.

 

It should also be noted that there is very little air pumped through the split air pipe in any gear except 5th. The split air solenoid doesn't open at all until the 5th gear switch triggers it. With the solenoid open, there is a 3/16" opening & a 1/16" opening in the ACV that allow air to be pumped though to the cat. But with it closed, only the 1/16" opening is available.

Basically, the air pumped into the port air path does 95% of the work to lower your emissions numbers. Not having the split air pipe can cause you to fail the visual, but not likely the tail-pipe test (unless you're borderline failing).

 

if your air pump, ACV, and cat work work then you could pass an emissions test without the split air pipe as long as you wouldn't fail a visual test.

 

Exactly. The split air pipe does next to nothing.

 

since that post ive passed smog on at least 2 different cars without it.