Bypassing acv
 

So this is my idea for an excellent modification to the stock emissions system...

How about removing the ACV and hooking up the air pump directly to the cat? Wouldn't that give the cat the right amount of air all the time? I could see why removing the ACV would suck for NA cars, but on turbo cars, we have no secondary ports anyway, so we don't need it.

What do you think?
-Ross

I believe that the ACV has other functions. not sure though. The air pump also generates different ammounts of air at different engine speeds so it would be hard to say if it would give the cats enough fresh air all the time.

It's been done before, and some people have reported success. But if you replace the cat with an aftermarket one that doesn't require air injection, you don't need to bother with this. If it did, Mazda wouldn't have needed the ACV. There must be a good reason why sometimes the air goes to the exhaust ports instead of the cat, and sometimes is dumped overboard. I just don't know what it is. ;)

the cat would melt in a few hours.... the ACV very rarly sends air to the cat.

it's good for emission testing. but unhook it as soon as you are done.