I am having trouble understanding some issues between Catless and Catted down pipes. Most likely any after market DP will cause P0240 code even if it is catted. Car will still run fine. Catless will add more power but will also throw the P115D code and the car won't run fine.
1. Will an O2 sim prevent both codes? if so then what are some benifits of catted. It seems pointless to get a catted DP if codes can be prevented.

I have some other questions but will address them after i get some responses and learn a bit more.

 

From my understand the O2 sim is SUPPOSED to fix any O2 sensor related issue when it comes to being catted/catless.

I have the ALTA turboback and the DP throws a code P0420. Just an annoying check engine light. It goes away it seems after a few days, and comes back on mostly when I am hard on my car, so maybe a day or two later.

 

well an O2 should fix both... but the only problem could come when you get emissions, if they use a sniffer... only way to get around that is go the opposite of a JCW exhaust... since JCW is only the primary cat and not the secondary and still passes it should be true that having a decatted downpipe and only have the secondary cat should give the same results or get some kind of custom job where the second cat is in place of a resinator (sp?... way to tired to be posting >< )

 

or option two is swap out your catless dp for your stock catted dp a few weeks before your emissions... not bad considering you only have to do it once every year... but still an inconvenience..

 

^^ If you do the later mentioned you may want to look into getting stainless studs for the turbo too. Breaking one would suck!

 

So if a sniffer is used in the emissions test, even with a catted i could fail? Swapping out my DP for inspections is not an option for me. My exhaust does not have a cat/resonator.

 

One is illegal and one is not...lol

Both will give you CEL lights....CEL's with both can be alleviated with a proper working O2 sim.

 

ok, So with a proper working O2 sim, there is no need for a OBDII reader with catless? and i am still wondering about passing emissions. Catless is pretty much going to not pass, and catted is a possibility? On monday i will ask my mechanic what they use for testing.

Again i am trying to figure out why i would get catted if an O2 sim is going to take care of any CEL lights. I also am not going to swap out everytime i have my car inspected

 

A couple of thoughts.... most likely any aftermarket downpipe wether catted or catless will throw a P0420 code at some point. The O2 sim you speak of is not actually on the market yet and the company that produces it is in questionable standing at best. If you are going to mod your car a code reader is something that you will eventually have to buy.

I am curious if others have gotten the P115D code, I think I have seen that CountryBoy has gotten it, just wondering how widespread this is.

 

I just checked into the DMV website and i'm assuming at catless DP is not going to pass a visual inspection of emission control devices..... so i guess it just leaves it up to whether or not it will pass a "sniffer" This is what i found on an unofficial website:
As part of this inspection, all vehicles will undergo a gas cap check, a visual inspection of the emission control devices, and a test of the chemical components of the vehicle's exhaust. This last test is more comprehensive in the New York metropolitan area, where it is referred to as the "high enhanced" emissions inspection. Outlying counties conduct the "low enhanced" emissions inspection. No matter where you live, the following emission-control devices will be examined if they were originally built into the car:

• Positive crankcase ventilation system

• Catalytic converter

• Fuel inlet restrictor

• Exhaust gas recirculation valve

• Thermostatic air cleaner

• Air injection system

• Evaporative emission control

 

why does it matter at that point if it passes the sniffer? Its an automatic fail when they see its not there...not to mention you'll probably have a MASSIVE fine along with your slip that says "fail."

If you live in a state where emissions testing is an issue, I don't know why you'd even bother with the hassle of not running a cat. Just get a catted downpipe and have no worries.

 

Thats what i am wondering. Why catless over catted if they both cause CEL issues, and if an aftermarket catted DP doesn't pass a sniffer (will it???) and you have to swap it out to pass an inspection, then what is the point?

Has anyone in NYC had any issues with an aftermarket catted DP?