Anyone running no CAT?

[scottyaurorav8]

Anyone here running no CAT?
Here's what I read. Running no CAT will increase both MPG and HP, but also read the fumes will be worse and the increase in noise/drone/vibration will be much worse.....

I'm not too sure though. I remember when I owned my supercharged Regal GS, another regal member got rid of his CAT and he said his car was faster, plus I don't recall it being much louder than mine. But maybe it's b.c it is a forced induction vehicle, would that change things?

I have Corsa exhaust which is pretty free flowing alrerady, but if I can gut my CAT out and have a complete free flowing exhaust, to maximize as much HP as possible, plus increase MPG, im all for it. If it makes it throatier, but doesnt make it much louder that be good. Just want to hear if any other members have done it with good results....

Would it throw a code too?

[RCA1186]

Yes it will throw a code.

[Kersh]

Yes, it will throw a code for the post O2 sensor being out of spec. It will also make the exhaust substantially louder.

I am running a "high-flow" cat and had found a noticeable increase in sound just going from the stock cat to the high-flow. By the same progression, I would expect the exhaust to be classified as LOUD if there was no cat at all.

Even with the high-flow cat, I was getting the post O2 code occasionally.

Also, I did NOT seem to get any (noticeable) increase in gas mileage OR power from the change.

This falls in line with things I've seen on other Cadillac/Northstar sites, removing the cat doesn't help.

[Randy T.]

Mine has been hallowed for years, I also hallowed lances and a few other Auroras. Not any sound difference until you step on the gas, and the sound exits out the rear, does not effect the interior sound. I am always riding dirty with a P0420, because the before and after cat o2 sensor get the same reading setting off a code, it can be easily fixed by setting one of the sensors in a little extension, a spark plug sleeve thing will work, Sall will tell you what it is called. A tuned computer can also get rid of the code, that is the route I am taking. Save the stuff you take out, you can cash it in for some dollars.

To remove it I hang the exhaust up, then use a drill with a drill extension and a wood paddle bit, get out what you can with that, stick a prybar up there to get big chunks out. For you it should be easier if your Corsa exhaust is held together with clamps you can separate it and pull it out easier, but if it was mine I would leave it together and pull the whole thing, the exhaust system comes out whole in about 15 minutes, as long as your bolts cooperate.

[sall]

Spark plug non fouler method or an O2 spacer.

www.energeticforum.com/renewable-energy/1387-o2-sensor-modification-using-spark-plug-non-foulers.html

o2-simulators.com/

I am using a spacer I bought on eBay. My '98 has no cat. And has no codes.

Randy's method works really well for clearing them out. I did the same thing on my S10. Except I used a long screwdriver and a hammer and not a crow bar. Whatever method works!

[scottyaurorav8]

Yea, I'll just get it cut out and gut it like you said Randy. So in your experience has there been any gains from doing this on the Aurora? One things for sure, with my corsa, it should sound mean as hell!!
As far as the code, I need to check, but I think I had madtuner eliminate that O2, so no code would be set...

[auroraandy1]

I hollowed mine out because it was clogged and causing a check engine code, and it was inspection time so the code was preventing it from passing. Although what I didn't know was that after I hollowed/emptied the catalytic converters guts out, that it would turn off the original check engine code from the cat being clogged, but turn on a different one (because the 02 sensor before the cat, compares signals between the 02 sensor after the cat, because with a cat installed properly it DOES show the before exhaust air which have not yet been filtered/gone through the catalytic converter, which reduces it's emissions so technically the 02 sensor after the catalytic converter should read out that the exhaust air/emissions is alot different/cleaner after being filtered/syphened through the catalytic converter and the emissions are cleaner between the reading from the pre-cat 02, then the after-cat 02 sensor).

HOWEVER if you have no cat, a spacer, or a hollowed cat the two 02 sensors the one before AND AFTER the catalytic converter are going to have the same/similar readings because there is no catalytic converter anymore to reduce emissions, but the car/PCM is programmed to believe one is always there so it believes the Catalytic Converter is fouled, too old, unefficient and not doing its job because the 02 right before and the 02 after/in the cat is going to be identical or close to it therfore thinking you need a new cat., and even if your cat dosen't seem that bad all it takes is the Converter to be 9% or more less efficient than it was brand new which dosent take ALOT.

And my car somehow has California Emissions (which means it was most likely bought in CALIFORNIA even though I and previous owner owned it across country in NEW JERSEY, so as soon as I hollowed it, the CEL Code was Insufficient Catalyst Reaction in bank 2, when the clogged one was installed I got Insufficient Catalyst Reaction in bank 1; either way I got rid of the SES code by buying a package of spark plug foulers (they come 2 in a package), and got the bigger size, screwed them both together, and I didnt have to saw off the threads of them because mine actually fit into the catalytic hole/slot where the 02 sensor went, and screwed 2 spark plug foulers together (the biggest ones and the middle ones), I used a middle and big one screwed together, so the big one the 02 sensor fit into after tapping it in very hard, and the middle size fouler at the outter which went into the catalytic converter port where the 02 went in, and it fit in but was not snug so had to put JBWELD around it to seal it.

And for some reason sawwing off the threads of even the largest fouler, are 02 sensor still dosen't fit in, I had pound my 02 into a huge fouler, and cut a piece of a thick pipe which I threaded into the 2 foulers into the end/large fouler and shoved it into the thick piece of pipe threaded into the fouler (and even then I could not fit the whole 02 inside, only about 1/2 of it the part of the 02 where it actually has holes/nozzles to read the exhaust).

But then cleared the codes with my OBD2 Bluetooth adapter and android ses reader/clearer phone app, and drove for 100 miles, and for once while doing the drive cycling and waiting for the catalyst monitor test to say PASSED (before without the foulers, I would clear the monitors, do the drive cycle and ALL of them would pass and the catalyst would be waiting to trigger the monitor, and as soon as you got the proper cycle it would say FAILED on my android OBD2 app for checking the monitors for emissions, it would pop up Catalyst: FAILED and as soon as that would say failed the Check Engine light would immediately turn on then too (and this took about 50-100 miles to have the code turn on, and for it to do complete all the emissions driving cycle monitors and pass all of them except catalyst (02 sensor would pass, 02 heater would pass, evap system would pass, egr system would pass, fuel system would pass but then the catalyst would fail and as soon as it did the check engine light came on for catalyst reaction inefficient).

But two spark plug foulers threaded together, and a piece of piping big enough in diameter to fit the 02 sensor inside but thread onto the fouler, and some rolling around under the car to get it into the 02 cat hole/slot, and pounding the 02 sensor into the pipe/fouler component and some JB WELD to secure it to the cat converter, I def. chose 2 foulers to make sure it filtered enough of the exhaust that it would be enough of a difference from the pre-cat 02s readings, and read cleaner because it got filtered through 2 pinlike holes before reaching the 02 sensors holes.

But end thing, do the fouler method (make sure to use 2 of them to be safe), and say goodbye to any SES/CEL CODES FOR GOOD and pass your emissions with no/hollowed out cat!

[auroraandy1]

And after hollowing out the cat I did notice a slight gain in performance/gas mileage, I thought the car would be ALOT louder but actually i'd say it only made it 10% louder TOPS, you can really hear the difference mostly at idle or WIDE OPEN THROTTLE from standing outside the car while it drives by, but it's not much of a louder difference!

[scottyaurorav8]

Well I have been strapped for cash so I havent been moving forward with this just yet, but when I do it, I think I'll have no issues with a SES light. I will confirm it with MADTUNER before I o it, but I believe he can deactivate the thrown SES code for running no CAT and that will solve that. I have Corsa exhaust so running no CAT will make it sound even meaner...Ill post some videos down the road when I completed this.

[plato442]

I'm running an aftermarket High Flow cat, an electric dump, and a Corsa cat-back dual exhaust and every once in a while throw a code. maybe because i open and close the dump often, but the dump is after the O2 so not as likely. However, the code is thrown rarely.

IMO, i would have an aftermarket high flow cat welded in rather than hollowing or removing cat. I bought a FLOWMONSTER Metallic High Flow Catalytic Converter PN 415250 and had it welded in. I took my old cat (without hollowing it) and took it to my local steel recycle place and they gave me $82.00 for it.

[lanceslambos]

it was tested on a dyno once and you can find the results posted on northstar performance or a cadillac club site I forget where now but a cat delete/ hollowed cat = 6 hp that's not enough to feel, hear or see and I doubt it actuially improves mpg w/o the 02 extension thing b/c the brain is having the car run lean to correct the issue it sees. just a thought. you can expect a little bit of drone but really it sounds exactly like straights and several here can confirm that (Collins, Randy T, Lathan) oh yea I have the resonator delete too.

[shelbyracing]

Every inch of exhaust pressure = about 1 hp loss. It's simple really my back pressure = less efficient cylinder refill. Lance is probably close with that assessment.
An 02 simulator works as well code wise.