The mechanic at mazda told me the other day about some kind of pressure module needed when gutting out your cat and installing a cat-back. i searched this up and i never heard of this before. anyone got any ideas? he said without this you could "burn your motor" .. this is the first i have heard of this

 

There is a like a little valve on the cat but I believe this is for emissions. I had a N/A and I eliminated it. I drove it that way for two years with no problems. I don't really think he knows what he is talking about.

 

Well eveything else i ask him he seems to know quite a bit. apparently he has worked on rotaries for years. he said it was the t2 that has needs this module and it is available from racingbeat but i couldnt find anything on it. :S

 

Maybe he was talking about the variable 6 port intake? It's activated by a hose from the exhaust system. How exactly it works, I forget.

 

He is probably referring to an FCD.

The Fuel Cut Defender fools the ECU into believing that boost levels are below about 8.5 PSI to keep it from cutting fuel. It's necessary if you plan to raise the boost on a stock ECU (which you will probably be doing by upgrading your exhaust).

However keep in mind that the FCD does not compensate for the increased fuel needs when you turn up the boost. Past about 8 pounds, you need to upgrade.

 

I wasn't planning on going above 8psi anyway because my motor is gettin high up in kms so i dont think it would be very safe running higher. but he had a different name for it .. like i am familiar with the fcd but he called it a brametric pressure module or somthing like that..

 

sounds like mechanic nonesense to me.

 

so if i were to install a cat-back and replace my cat with a straight pipe then is a fcd nessesary? what will happen without one?

 

Without an FCD, the car will hit fuel cut everytime you hit ~8 PSI of boost. To prevent an overboost situation the ECU will cut all fuel to the rear rotor. It feels like the car is hitting a wall.

 

Ok, stupid question, but I've been wondering this for a while...

If you "gutted" out your cat, wouldn't the effect be the same as installing the straight pipe? Which is coincidentally the same question Aaron answered, probably minutes ago, on this thread: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/question-about-straight-pipe-88-na-739399/

If that's the case, I'm thinking you'd need something to provide the back-pressure (ordinarily provided by the cat) to open the aux ports.

So I don't know about the "burn your motor" comment, but your overall performance would certainly suffer.

I don't post much 'cause I can usually find the answer by searching

 

so if the ecu hits fuel cut can this cause any damage?

 

Obviously the FCD. And yes thats a fuel cut not spark cut, so things could possibly lean out and go boom.