Jay J

I have some DANSK Cat bypass'es in my 96' 993 (I don't drive it much only on Fridays/Saturdays); and a Prius is my DD so I guess it offsets emmsions lol

Now my question I have is,
Should I just safety wire them in the engine bay? for my secondary 02 sensors for the left and right bank?

I will eventually switch over to some ceramic 100/200 cell cats when I start racking up more miles on her.

John@Fabspeed

You can safety wire them out of the way and you will be just fine. If you want to, you can have bungs welded in the pipes very cheaply so you can install them.

Jay J

I thought secondary 02's would burn out if put into a car with cat bypasses?

993inNC

No even worse, you'll burn your motor up! The ECU goes lean and bad things begin to happen quickly! DO NOT install them in a cat delete pipe. You can wire them up out of the way, but you will throw a CEL because the system won't have a reading from the post O2's. The car will run rich (not a bad thing) and may smoke a bit more than usual (depending on the condition of your valve guides etc...).

Also, 100 cell cat pipes will still throw a CEL most times. 200 is more flow than your motor will ever put out, so go that way.........Oh and.......

Evan, buddy, research before chiming in on such an important topic and giving advise like that!

chaoscreature

I don't know the specifics about the Porsche ECU, but OBDII standard is that the pre-cat O2 Sensors are the only ones that affect the fuel mixture, the post-cat O2 sensors are for monitoring the emissions system.

100/200/300/400+ cell cats can all be super efficient or very bad, the quality and quantity of the precious metal coatings on them are as or more important than the cell count. I am running 100 cell cats that pass CA emissions tests easily and they have what I would consider a medium loading. Not all aftermarket cats are made the same.

Jay J

I was under the assumption of what you posted as well. I just had both the primary's done.