deleting the cat. convertor

[kc2005ptgt]

Ok, I have read conflicting result, and am wondering, if you delete the cat, or remove all the crap inside, or replace it with a straight pipe, if you still keep that downstream o2 sensor plugged in, will it throw a code, and will it hurt performance? If it does throw a code, isn't there a fix for it??? Some way to fool the sensor? Sorry, I know it was covered, but I hear conflicting things, and wanna know facts before I decide to remove/delete/replace the cat.

Here is an example of one thread I read that gave good info, but I am not sure if I understand it, or if it fully answers my questions: http://forum.2gn.org/viewtopic.php?t=18406

[Kevin_GP]

You will throw a code if you disconnect the sensor, leave the sensor pluged in but zip-tied on the frame (so it reads atmosphere), or you leave it in the exhaust. You will throw the cat failure code sometime any of these ways. You can use the spark plug fauler method, which should work, but even then you might throw a code eventually. Some people use some resister things, not sure about that.

You wont gain anything NA, unless you have a beastly build going on. Gutting your cat is useless if you are NA, you will mostly lose power. If you are asking if the code hurts performance, short answer no. Again if you are NA you wont see a difference. When I was using the stock computer and the code was thrown, my car ran BETTER, but I have a different setup than everyone else. You wont see a difference.

[INVUJerry]

You could do the "non spark plug fouler" mod to avoid a CEL. Linky


I would recommend if you are going to delete it, to go with a straight pipe and not a hollowed cat, since it will create a lot of turbulence.

[quicksilvr]

You will throw a code if you disconnect the sensor,

Only if you cruise at constant rpm. I have my downstream completely disconnected (the sensor is sitting on the shelf in the garage) and I drove for over 3 months in Kirksville and never threw a code. It was because it was stop and go in town. As soon as I get out on the highway, within 5 minutes P0140 pops on.

That said, I was under the impression that the code being stored didn't hurt performance, but one day after I cleared the code, the car seemed alot peppier. There is a high probability that it was my imagination. No hard facts here. I do know for sure that the car runs GOOD with the code showing....and it might run a tad better when it's not showing, but who knows.

[gilly02le]

mines shown p0140 for a long time because i dont have the lower o2 hooked up.. definatly doesnt hurt performance, i will say when i had no cat, the car sounds worse, as the cat works as a resonator and takes out some of the pops and raspyness. I'd say if you want the cat eliminated, have a downpipe made with a 4-bolt flange.. so it works with your stock setup.. wouldnt imagine that would cost all that much.. especially if you got your hands on a flange from a junkyard.. this way if you need/want to, you can throw the stock cat and dp back in there.. handy if you have inspections where you live..

[MoxHair]

Just get a Stage1 ECU.. thats what I did..

[Kevin_GP]

You will throw a code if you disconnect the sensor,

Only if you cruise at constant rpm. I have my downstream completely disconnected (the sensor is sitting on the shelf in the garage) and I drove for over 3 months in Kirksville and never threw a code. It was because it was stop and go in town. As soon as I get out on the highway, within 5 minutes P0140 pops on.

That said, I was under the impression that the code being stored didn't hurt performance, but one day after I cleared the code, the car seemed alot peppier. There is a high probability that it was my imagination. No hard facts here. I do know for sure that the car runs GOOD with the code showing....and it might run a tad better when it's not showing, but who knows.

Indeed, Im pretty sure at one time or another you will trip your CEL with the spark plug fouler, disconnecting, or just zip tieing. I zip tied mine just because, and I would be good for a couple days sometimes weeks, then I would trip it. Im not sure about the whole performance thing because for whatever reason my car idles a hell of alot better when I triped the CEL, but my situation is different than everyone eleses.

[quicksilvr]

You will throw a code if you disconnect the sensor,

Only if you cruise at constant rpm. I have my downstream completely disconnected (the sensor is sitting on the shelf in the garage) and I drove for over 3 months in Kirksville and never threw a code. It was because it was stop and go in town. As soon as I get out on the highway, within 5 minutes P0140 pops on.

That said, I was under the impression that the code being stored didn't hurt performance, but one day after I cleared the code, the car seemed alot peppier. There is a high probability that it was my imagination. No hard facts here. I do know for sure that the car runs GOOD with the code showing....and it might run a tad better when it's not showing, but who knows.

Indeed, Im pretty sure at one time or another you will trip your CEL.

Agreed.


Side note....do you still have some hair left from your MS ordeal? Sorry I can't help much, I was just talking to my brother about it last weekend when he was here. He's somewhat stumped....plus it's hard not being able to actually work on it in person...internet communication pwns sometimes. Whatever the case is, I hope you're able to get the car setup the way you want...MS or no. I still have hope for your MS though.

[Kevin_GP]

Only if you cruise at constant rpm. I have my downstream completely disconnected (the sensor is sitting on the shelf in the garage) and I drove for over 3 months in Kirksville and never threw a code. It was because it was stop and go in town. As soon as I get out on the highway, within 5 minutes P0140 pops on.

That said, I was under the impression that the code being stored didn't hurt performance, but one day after I cleared the code, the car seemed alot peppier. There is a high probability that it was my imagination. No hard facts here. I do know for sure that the car runs GOOD with the code showing....and it might run a tad better when it's not showing, but who knows.

Indeed, Im pretty sure at one time or another you will trip your CEL.

Agreed.




Side note....do you still have some hair left from your MS ordeal? Sorry I can't help much, I was just talking to my brother about it last weekend when he was here. He's somewhat stumped....plus it's hard not being able to actually work on it in person...internet communication pwns sometimes. Whatever the case is, I hope you're able to get the car setup the way you want...MS or no. I still have hope for your MS though.

Im going freaking crazy, mostly my fault but its just problem after problem. I've been having personal problems (broke up with my gf and shes been moving out of my apartment) so thats really been delaying everything. Hopefully I will have it running soon if not I will just take it out and install it later with someone that can help me out (im basically working alone in a parking lot, it takes all the fun out of things).

[quicksilvr]

Im going freaking crazy, mostly my fault but its just problem after problem. I've been having personal problems (broke up with my gf and shes been moving out of my apartment) so thats really been delaying everything. Hopefully I will have it running soon if not I will just take it out and install it later with someone that can help me out (im basically working alone in a parking lot, it takes all the fun out of things).

Understood. That situation sucks for sure. Dude, if you split the airfare Josh and I will fly down and help ya out. Maybe.

[Kevin_GP]

Haha, If I had anyones help (that knew alittle something about cars and computers) I would have been done with this. I just hate computers! And I hate working on something like this by myself. I am just having one of those times when everything I touch goes wrong, so I am backing off for now.

[kc2005ptgt]

You could do the "non spark plug fouler" mod to avoid a CEL. Linky


I would recommend if you are going to delete it, to go with a straight pipe and not a hollowed cat, since it will create a lot of turbulence.

Some people get the code back though - what about you - did you ever get the code? I am going on friday to have my muffler guy take a look at my exhaust and he is going to see what he can do - he is talking about removing cat and installing a downpipe in replacement of the cat, and welding in an o2 bung

[OverDrive418]

That won't work, tried it. It has to do with where it's positioned for some reason. Fart too close to a Neon and an emissions code will pop up! Last I checked MP had OBD-II compliant high flow cats, why not one of them?

[quicksilvr]

You could do the "non spark plug fouler" mod to avoid a CEL. Linky


I would recommend if you are going to delete it, to go with a straight pipe and not a hollowed cat, since it will create a lot of turbulence.

Some people get the code back though - what about you - did you ever get the code? I am going on friday to have my muffler guy take a look at my exhaust and he is going to see what he can do - he is talking about removing cat and installing a downpipe in replacement of the cat, and welding in an o2 bung

I guess I never asked...why are you wanting to get rid of the cat andy? I'd leave it alone on a car with as low of miles as yours....and you're not running a long tube that requires the room. If you do want to ditch the stocker, I'd get a high flow aftermarket unit and keep your emissions looking nice and "al gore" friendly.

I kind of wish I had a cat.....

[OverDrive418]

And keep your Db levels down.

[kc2005ptgt]

You could do the "non spark plug fouler" mod to avoid a CEL. Linky


I would recommend if you are going to delete it, to go with a straight pipe and not a hollowed cat, since it will create a lot of turbulence.

Some people get the code back though - what about you - did you ever get the code? I am going on friday to have my muffler guy take a look at my exhaust and he is going to see what he can do - he is talking about removing cat and installing a downpipe in replacement of the cat, and welding in an o2 bung

I guess I never asked...why are you wanting to get rid of the cat andy? I'd leave it alone on a car with as low of miles as yours....and you're not running a long tube that requires the room. If you do want to ditch the stocker, I'd get a high flow aftermarket unit and keep your emissions looking nice and "al gore" friendly.

I kind of wish I had a cat.....

Forgive me if I am wrong, but isnt the cat a restriction? Removing it will release some hp, yes? Also, here is another thing - wish I could post a pict of it - but if you look at the bend from the cat to the straight pipe, that pipe is like 1 3/4"-2" in diameter, and is a definate bottleneck, so by removing that whole piece, it should help too, yes? And finally, I do want to install a high flow cat in the stright pipe area under the car, eventually, so it will stay "Al Gore Friendly" - please corrcet me if I am wrong in my information and assumptions. I am having him look at the possibilities tomorrow as it will be up on the rack and he is going to look at it.

[03blackrt]

Yes, the cat is restrictive by nature (because of all its surface area).

[kc2005ptgt]

well, I changed my mind about the cat - I am torn, it was not cheap to do, but the problem lies in that in my car the o2 sensors are #1 on the flange of the cat and #2 in the cat - so it would be a big deal, would have to remove cat, etc etc etc... anyway, I dunno... I just may buy the this: http://www.modernperformance.com/dcx/mp ... gnum.shtml

eventually... hell, maybe I should just wait and go turbo in 2 years

[gilly02le]

whats the issue your lookin at the with the o2 sensors man, if its a question of wire length, mail me your sensor, and ill extend all four-wires, heatskrink it and make it watertight.


P.s - For anyone who needs o2 sensors, i just bought two universal borg-warner sensors.. 59 dollars canadian TOTAL, for both sensors.. Im very happy spending half what the dealer wants, for just one sensor, on two!

[Jamie]

For an NA application you do want some backpressure in the system.

For a turbo you want as little backpressure as possible in the system. so the turbo doesnt have to work against the exhaust system to spool up. (little more complicated than that but yea... )

i have heard of people losing HP by deleting the cat. there is a guy named asanti on howells board who is NA and lost hp by taking his out. hope that helps!

good luck
J

[03blackrt]

For an NA application you do want some backpressure in the system.

Backpressure is always bad.

[gilly02le]

Backpressure creates low end torque

[03blackrt]

Backpressure is always bad. It inhibits performance.

[fixitmattman]

When will people figure out the truth about 'backpressure.'

First one to post where the myth of backpressure comes from and why it no longer applies to todays cars gets an e-cookie or an e-beer, your choice.

[03blackrt]

'Backpressure' is not a myth. However, the way most precieve it is.


Hon-dua

[gilly02le]

bigger piping = more volume, less velocity, meaning less scavenging at low rpm's... so it's not a lack of backpressure

[fixitmattman]

For argument:

You've upgraded your exhaust with pipe of the same diameter, but a less restrictive setup (low restriction muffler, mandrel bends).

Keep going.....

[gilly02le]

talking about me?