Rear cat delete

[JTKustoms]

I know this has been discussed before and a few of you guys have done it but I'm looking to get a few answers. I went to the shop that did my exhaust a few years ago and asked about either deleting the rear cats or putting a basic cutout between the front and rear cats on each side. I was told it would deff give me a check engine light by deleting and that there is not enough room between the front and rear cats for a cutout. I'm just trying to see what modifications, if any, would be required to delete the rears without any engine light issues. Any help would be appreciated because i wanna do it soon

 

[WSS1]

Can a good custom tuner write up a tune and eliminate the 02 sensors or whatever it is that will throw the code?

 

[panda24619]

it wont throw any codes. plenty of people on here have done it with out one problem. except bad mpg, the sound of the engine is so good that they cant keep the lead foot off the skinny pedal. but in theory your mpg should increase. i would do it, but cali dosent allow it.

 

[JTKustoms]

So panda from what I understand there is an o2 sensor before the first cat then another after the second cat, and by deleting the second cat I won't have any issues with the o2 noticing a missing converter?

 

[GAINMOB]

i remember being given the answer that it depends on where the 2nd o2 sensor is placed on the rear cat...i believe if the sensor is on the front of the rear cat we're good...if on the rear of the cat...CEL...when i get my exhaust done again i am looking at doing the delete as well...search rear cat delete or similar early 2011...i think thats when all that talk went down...they may have made a sticky...idk...should be a sticky though...common question

 

[toms89]

The front o2's are critical for tuning. When the ecu goes into closed loop it is the front 02's that the ecu used to adjust the air/fuel ratio. These are ahead of the cats because the ecu needs unmodified air fuel readings from the motor to properly tune. The rear O2's are strictly for monitoring the effectiveness of the cats and can be turned off in tune as said. You may need a custom programmer to do so.

As panda said many here have deleted the rear cats with no cel's. Apparantly the front cats run clean enough that the ecu believe its with-in limits.

 

[tallsville]

if i remember correctly some have welded bungs on the pipe to(for lack of a better phrase) pull the rear o2 out of airstream.

 

[WSS1]

it wont throw any codes. plenty of people on here have done it with out one problem. except bad mpg, the sound of the engine is so good that they cant keep the lead foot off the skinny pedal. but in theory your mpg should increase. i would do it, but cali dosent allow it.

I have never understood the reasoning with cali, if I am getting better mpg, isn't that less pollution? I just did a cat on a jeep for a friend and found that we are very special! It had to ba a certain cat (1 state as opposed to a 49 state). Ahhh, the republic of California.
LOL

WSS1

 

[tallsville]

yep. funny thing is spintech makes a hiflow cat that cant be used in the state that its made in. Thank CARB for the restrictions. but also remember we have 12%(1% in L.A. alone) of the US population in CA. alot more people and cars so have to offset the amount.

 

[Thermo]

Better mileage does not mean less pollutants. Do some looking around on the internet for "Mythbusters Bike Vs. Car". They compared a few different vehicles to each other and then also compared a few motorcycles to each other along with comparing a car to a bike. Obviously, the motorcycle had much better mileage, which using your thought process, would mean that you emitted less pollutants. What they discovered was that even using a "modern day motorcycle with low displacement" (use a 2012 250 CC bike as I recall) with a custom wind faring to help with its aerodynamics to make it the "most green it could be", the emissions coming off of the bike were around 10 times as much as a standard car. The bigger displacement motors actually can burn the fuel more completely, resulting in lower overall emissions since the fuel can spend more time in the fuel chamber (you never see a V16 train locomotive up at 10,000 RPM).

So, you can not relate mileage and emissions to each other. There are far more factors into the emissions than just the one.