Removal of the rear cats...

tbone said:
As long as it goes faster and sounds better, who cares about mileage?
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Good note / Mine sounds better [more rumble at idle - Mid range pulls harder and 1/2 to 3/4 mile per gallon gain and this is with a D.R. Tune :beer:
 
Bro.. It won't cause an CEL to come on. It will make the exhaust sound a whole lot better even with factory mufflers. I can post a YouTube video of my mufflers with aero turbines before and after cat-delete if u want.
 
Oh yea.. Removel(removal) is spelled wrong.lol! Seriously I guess it will depends on how your inspection goes and how you tell(lie) to your inspector. Or move to Alabama, not to brag, but I've heard cars that sound like monster trucks!(no mandatory inspections yet.)
 
OK, I stand corrected about the rear cat delete and no CEL associated with it.

But that still leaves the logic question. Tunes usually have the rear cat logic turned off. Wouldn't that give a "not ready" code for that parameter?

I took my car into the dealership for a diagnosis on a unrelated problem and they informed me I needed two CAT assemblies. I didn't get them but they sent me to an exhaust shop (sub contractor) to have the system tested using some sort of pressure tester and drilling a small hole in the exhaust pipe. System checked OK, later I thought maybe it was because my CAT logic was turned off.

My point being, something in the OBDII test keyed the technician that the CAT system was faulty. Would the OP's car also fail this test if logic was turned off?

Don't mean to be picky but it may help to get answers before he commits to alterations of his emissions components.
The fine for this is tremendous. Go to any muffler shop and the warning signs are clearly posted.

For those of us in non-emissions testing states, no big deal. What happens when you sell the car and the new buyer gets tagged.

Sorry for being a pain in the arse.
 
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martyo said:
I use Jedi mind force to channel my exhaust.
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O.M.G. Marty! Quote worthy!





MrBluGruv said:
MISINFORMATION PEOPLE!


Goodness, people have only been doing this for years, I would've thought it'd be understood now.


Your REAR catalytic converters have no efficiency monitors on them, so removing them makes no difference to the computer, it will never know the difference, you WILL NOT throw a code.


The exhaust chain in regards to emissions control flows like this:

Manifold -> 02 sensor (for A/F monitoring) -> primary catalyst (smaller set) on the down pipe -> 02sensor (for catalyst efficiency monitoring) -> secondary catalyst (larger set) -> rest of exhaust.


You should most definitely notice a volume increase unless you just have super quiet mufflers, in which case you may consider going that route first.
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Correct.


FrankJAG said:
Your check engine light will come on
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Incorrect.






tbone said:
If you are talking to me, there is no visual inspection here.

My rear sensors are turned off, rear cat deleted, no light, and I passed the OBDII inspection with no problem. The front sensors are before the first cats, so how would the car know if the cats are gone? I'm golden.

If you're referring to airjordan, mrblugrv is correct.
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If what you say is true, then you can now remove the front cats too, but probably wouldn't sound the best using stock manifolds.
 
Im getting confused here.. WILL I BE OK IF I DO THIS?? Cause i went yesterday and after the guy told all that i asked my question on here to get a correct answer.. If its fine ima go ahead and do this today.
 
airjordan2k8 said:
Im getting confused here.. WILL I BE OK IF I DO THIS?? Cause i went yesterday and after the guy told all that i asked my question on here to get a correct answer.. If its fine ima go ahead and do this today.
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Stop being a Nancy and DO IT!!! What's the worst that can happen? You fail your inspection and get them put back on for $50. Easy...
 
Pat said:
OK, I stand corrected about the rear cat delete and no CEL associated with it.

But that still leaves the logic question. Tunes usually have the rear cat logic turned off. Wouldn't that give a "not ready" code for that parameter?

I took my car into the dealership for a diagnosis on a unrelated problem and they informed me I needed two CAT assemblies. I didn't get them but they sent me to an exhaust shop (sub contractor) to have the system tested using some sort of pressure tester and drilling a small hole in the exhaust pipe. System checked OK, later I thought maybe it was because my CAT logic was turned off.

My point being, something in the OBDII test keyed the technician that the CAT system was faulty. Would the OP's car also fail this test if logic was turned off?

Don't mean to be picky but it may help to get answers before he commits to alterations of his emissions components.
The fine for this is tremendous. Go to any muffler shop and the warning signs are clearly posted.

For those of us in non-emissions testing states, no big deal. What happens when you sell the car and the new buyer gets tagged.

Sorry for being a pain in the arse.
Click to expand...

This happened to me when I bought my first Marauder, took it for inspection not knowing the Cats were deleted, they checked and I failed.

Went to the shop, installed Hi-Flow Cats for a few hundred bucks, passed and din't notice a huge difference in the performance for the car or the sound.

I'd say he can do it, worst case scenario it will cost a few hundred dollars to get it back as a lesson learned
 
justbob said:
If what you say is true, then you can now remove the front cats too, but probably wouldn't sound the best using stock manifolds.
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I'll remove them when I get the Stainless Works headers. Until then, my car has a perfect exhaust system, in my oh so humble opinion!:burnout:
 
This thread makes me laugh. Ton of misinformation with the truth sprinkle in here and there.

You should not fail inspection in Texas for removing the rear cats. All my ford vehicles have the rear cats removed (three currently and had 2 previously registered in Texas) and None have ever thrown a code or failed inspection. I'm in Houston.

EDIT: so people don't take my post the wrong way, I'll explain a bit what I mean: forums are a great source of information. problem is that everyone thinks they are experts and gives their two cents without thinking about what the OP asked, or ever worse, gives the OP wrong information. So the issue becomes having to dig through BS to find the real answer. The same logic applies when searching for old threads on an issue. Lots of discussion but no conclusion. For example, I posted a thread about using 98 cobra cams in a built supercharged application. I felt like one poster in the thread effectively was calling me an idiot becuase the topic "has been covered/beaten to death" and that I should have done a search. Well, I did search prior to posting and I didn't find a consistent answer. This same person then asked the exact same question that I had a couple days laters because he didn't know the answer. So I am left wondering why he posted in my thread saying the topic was covered?????? Point: too many opinions and not enough people in the know. Have a good day.
 
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