Ok I have a replacement catylitic converter for the Rex, it doesn't have a "Little tube" comming out of it like the catco that is on there does, what does the metal tube that heads to the motor do? Can i run without it and will the car function properly? sorry for the non technical terms such as "the thingy"...and what not...

Trevor

 

that tube leads to the air pump. the replacement you got is probably a universal? the air pump lets fresh air into the converter to increase it's efficiency. that replacement may not actually work for your rx7 (by work i mean pass emmisions or last long), but i'm not exactly up on new catylitic converter technology so maybe there is something about it that i don't know.

 

Yeah it's basically a straight through cat i got for my honda accord but never put it on.... I was hoping to get it to fit.....oh well, i guess i'll have to hollow out the CATCO that is on there now....unless anyone else knows a way around the tube?

 

Wow. How very wrong.


That line from the cat goes to your LIM. It actuates your 5th/6th ports. It does NOT go to the air pump. The air pump does NOT send air down that line to the cat, although people have rigged temp setups to do just that to pass emissions.

 

S5 pump air into it, S4 use that too get back pressure.

 

If it actuates the 5th and sixth ports then i can't run without it right...unless i wire the ports open...?

 

No. It's a combination of the above answers. That is called the Split Air Pipe. It has dual functions. One is to feed air to the catalytic converter under certain circumstances such as being in fifth gear....the other reason is that you WILL find on that pipe, near where it connects to the engine a mushroom shaped device that is a check valve. That is to keep exaust gasses from the cat going back into the engine. What is important, is that there is an approx one eighth inch tube that splits off the Split Air Pipe. Its about an inch long and a vac tube is connected to it. That vac tube goes to a nipple near your rear auxillary actuator and feeds pressurized air to the auxillary port actuators FROM the exaust pressure.

Yes, you need to have a cat with the small air pipe coming off it, if you want the cat to work right and for the auxillary ports to open. That's a must for the aux ports.

 

There. All better.

 

We knew you new goooder!

 

Wow. How very wrong.

That fresh air line eventually leads up to the ACV. The ACV feeds air to either the exhaust manifold (via ports in the bottom of the rotor housings) or the cat, via that long tube that ALSO connects to the port actuators. The cat (at least the stock Mazda cat) needs fresh air to react properly. When you are cruising in 5th gear, the ACV is constantly feeding air to the cat via that tube.

 

LOL!! This is the most entertaining thread I have read all week..