I'm just about to have a Remus exhaust and new 2.25inch pipe work installed on my 2002 P5. I had a look underneath the car today and wanted to ask a question about what i saw.

I know that the car has 2 cats and 2 sensors. When you open the bonnet you can see that one of the sensors is connected to the 1st cat. Now, i always thought that the 2nd sensor was just the same, connected to the 2nd cat. But when i had it up on a hoist today and had a look, I saw that it wasn't. The 2nd cat. does not have anything connected to it. The 2nd sensor is actually about 20cm up the pipe (towards the engine/1st cat.). Between the 2nd sensor and the 2nd cat. is the bolted pipe connector.

The question i have is this: if the 2nd sensor isn't connected to the 2nd cat., then can i just take the 2nd cat. out of the system. I would then have the 1st and 2nd sensors + the 1st cat left in the system. Is this o.k. Does anyone know otherwise. If anyone can help me it would be much appreciated.

Thanks
TDK

 

yes

 

More specific answer...

No, there are no O2 sensors that monitor the secondary cat. Removing the secondary cat will have no negative effects on drivability or performance and it will not turn on the MIL, but it *will* effect emissions. I'm not sure about the legal ramifications of removing this cat in Australia; it's illegal in the U.S.

 

First things first: Nice choice on the exhaust. PLEASE post some pics when you're done with the installation.
Now...I think that by removing the second cat, your car will go from ULEV to LEV, and still pass smog. I'm pretty sure that the Spoolin turbo does away with the second cat.

Here's a thread that might be some help(just keep reading):http://www.protegeclub.com/forum/sho...threadid=20348

 

A P5 with no secondary cat will *not* pass a proper visual inspection in the U.S., and ESPECIALLY not in California. Removing a cat without replacing it with another cat is illegal in every state; some states require replacements to be identical to OEM (such as CA), other states will allow non-identical replacements as long as performance is "equivalent" (such as TX), but it doesn't matter if the resulting vehicle still meets LEV standards; that's beside the point in the law books. It is still illegal. Of course, there's always the chance that the vehicle inspector will be a n00b and not realize that a P5 is supposed to have a 2nd cat, but that doesn't change the fact that the vehicle is technically not in compliance.

Of course, this still doesn't answer the question according to Australian law, but I'm just clarifying things for U.S. owners so nobody begins to get confused.

 

So, apart from the legal issue i guess we all agree that removing the 2nd cat will not effect performance, sensors, and any warning lights.

If this is the case then i will remove the 2nd cat and run a 2.25inch pipe from the cat pipe bolted connector to the remus muffler. All pipes will be mandrel bent.

Also, what would happen when they finally bring out Headers for the P5. This would mean that i would need to remove the 1st cat aswell. Now, you can't drive around without ANY cats. So could i then install a new cat where the 2nd used to be?

As for the Australian regulations, i believe that we are no way as strict as California. This is why we can import cars from Japan that are not compliant with their regulations. Also, when we are renewing our registration we can have any registered mechanic do the rego. inspection. This means that i can go back to the people that installed the exhaust system and have them perform the rego. inspection (IF they are registered, which most are). And you know they are going to approve it, otherwise they will show they are doing something wrong. But i also believe that you shouldn't go overboard, if everyone was doing this then the environment would greatly suffer.

Thanks to everyone on their help. I'll post some pics once i have them.

TDK