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How did I pass emissions for years....with a gutted cat?

Old 05-31-2012, 09:12 PM
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How did I pass emissions for years....with a gutted cat?

I'm second owner, and as mentioned elsewhere, among other things at 60K I'm replacing the catalytic converter due to cat efficiency engine trouble code. And RX8's need them at around 60K pretty often anyway....I got a good deal...didn't look much more into it, and just planned to replace.

Last I got the trouble code, I reset it, and it stayed off long enough to pass emissions...came back on a few weeks later...and I've put it off since (about a year). But before that, no issues for a few years. And, it's had a factory computer reflash early on when I had it...so I don't think it could be an ECU mod?

So, I get the old converter and pipe off tonight....and....it's empty. I've been running a gutted mid-pipe with no catalytic converter actually in it (made to look stock though) without knowing it. The only other thing was the rear oxygen sensor was moved back onto the pipe about 1 foot, and the stock port was welded shut.

How did this ever pass emissions and also not throw trouble codes, for years? Would just moving back the oxy sensor be enough?

I always thought my (aftermarket) exhaust was a little louder and smellier than it should be... ...turns out, there was a reason. :p

(And, uh...since I have a new cat on it now -- how much can I sell this stock looking mid-pipe for? )
Old 05-31-2012, 10:13 PM
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Most likely they gutted the first cat. There are two.

Also a possibilty that the car was tuned with Accessport and the seller never changed it back to stock map before selling.

Are you sure it is a mid pipe?
Old 06-04-2012, 11:11 AM
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Well....ran a wire through the whole piece. Completely empty.

New cat and 02 is mounted, so I'm not really worried about it. Just surprised.

Anyone want a gutted cat (with an unknown condition rear 02 sensor)? :D
Old 06-04-2012, 11:16 AM
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I'm guessing you don't have sniffer emissions tests? It would have failed that for sure, but if it's just an ODB2 check, then yes, it's entirely possible. Removing the cat elements (either from the pipe, or removing the entire cat itself) is not a guarantee of throwing a "missing cat" related failure code on our cars. Quite a few people never get the CEL (without masking it either), some people get it immediately, and others get it intermittently. If it was just ODB2 emissions checks, all they do it check to make sure that there are no codes listed for the emissions system not working right, assume that it is correctly working, and give you a passing grade.
Old 06-04-2012, 11:25 AM
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Originally Posted by DCat22
Well....ran a wire through the whole piece. Completely empty.

New cat and 02 is mounted, so I'm not really worried about it. Just surprised.

Anyone want a gutted cat (with an unknown condition rear 02 sensor)? :D
Where you located at?
Old 06-05-2012, 01:46 PM
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Originally Posted by tronicj
Where you located at?
Inside the loop in Houston, actually.... I'll PM you a pic when I get home.

I'm not 100% sure it's stock, but I think it is. Includes the two "spring bolts" from the rear end. I reused the seals that were in good shape, and the front side bolts.

I installed a new rear 02 sensor on my new cat, since it was $60....but the one on the old pipe there might be good (enough)...no idea.
Old 06-05-2012, 02:31 PM
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Originally Posted by DCat22
Inside the loop in Houston, actually.... I'll PM you a pic when I get home.

I'm not 100% sure it's stock, but I think it is. Includes the two "spring bolts" from the rear end. I reused the seals that were in good shape, and the front side bolts.

I installed a new rear 02 sensor on my new cat, since it was $60....but the one on the old pipe there might be good (enough)...no idea.
You should come out to the meet next week. My 8 should be running again by then.
Old 06-07-2012, 07:47 PM
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Originally Posted by DCat22
Well....ran a wire through the whole piece. Completely empty.

New cat and 02 is mounted, so I'm not really worried about it. Just surprised.

Anyone want a gutted cat (with an unknown condition rear 02 sensor)? :D

I am in Dallas, but I can come and get it if the other guys does not get it. Let me know.

Thanks.
Old 06-09-2012, 06:17 PM
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Well, I got the car all back together today...and it still works! (60K mx, replaced...what feels like everything.)

Holy crap the console and footwell get hot with a real cat down there! I'd read the threads, but always thought that was overblown...I burned my finger touching the passenger seat rail bolt.

For now I'm going to hang on to the gutted mid-pipe. I might swap it back on once I get my inspection...just because of the heat, aside from...well, the car doesn't sound as nice any more either. (And I think with all the tune-up work I did, it may pass with the midpipe again too.)

I'll bug ya'll if that changes. (I drive to Dallas once a month.) Thanks again!
Old 06-09-2012, 06:19 PM
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You should still come out Tuesday!
Old 06-09-2012, 08:40 PM
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Originally Posted by DCat22
Well, I got the car all back together today...and it still works! (60K mx, replaced...what feels like everything.)

Holy crap the console and footwell get hot with a real cat down there! I'd read the threads, but always thought that was overblown...I burned my finger touching the passenger seat rail bolt.

For now I'm going to hang on to the gutted mid-pipe. I might swap it back on once I get my inspection...just because of the heat, aside from...well, the car doesn't sound as nice any more either. (And I think with all the tune-up work I did, it may pass with the midpipe again too.)

I'll bug ya'll if that changes. (I drive to Dallas once a month.) Thanks again!
Yes, the heat buildup is the biggest disadvantage to having a cat, and makes many of us do everything we can to avoid running one.
Old 06-14-2012, 07:33 AM
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Originally Posted by RIWWP
If it was just ODB2 emissions checks, all they do it check to make sure that there are no codes listed for the emissions system not working right, assume that it is correctly working, and give you a passing grade.
I had the emissions on my 2004 checked just two days ago, in Maryland. The ODB2 check is all they did.

My last car was a 1993 Fort Probe GT, another fun car, but getting a bit elderly. No ODB2 port, so they had to do the actual exhaust gas emission test.
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