Cat delete and x-pipe questions

EnderG60 · 10-13-2015, 07:26 AM

First off I am a noob but I have been searching for the past 2 weeks and still have questions I cant find answers to.

I realize the primary 400 cel cats are the big restrictions and would like to remove them. I would like to retain the secondary (or aftermarket high flow) cats which appear to be 200 cel for both stock and high flow aftermarket and resonators so I can pass emissions and not have a gas smell.

I see that all tunes only turn off the rear O2 sensor, which will stop the check engine light but wont pass the "readiness test" for emissions. I have heard the Evolve tune fixes this readiness issue but when I inquired about it I got no response.

I also see that most aftermarket x-pipes have the O2 sensor bungs in the stock locations and the high flow cats after that which makes no sense to me, and O2 extenders probably will not work either.

So Im left with these questions....

If I get test pipes like the Macht Schnell test pipes and the primary cat is removed correctly, can the stock cats be re-installed using the clamps that come with the test pipes?

Has anyone tried relocating the rear O2 sensor behind the secondary cat? Or is there an x-pipe out there with high flow cats and the O2 sensors behind them? And if so has this worked for emissions?

s14_kev · 10-13-2015, 08:01 AM

RE: Test Pipes. Yes you can reuse the clamps to swap between OEM cats and test pipes. I have the OEM cat on my car with clamps. Just know that the seal may not be 100%.

RE: X-Pipe with HFC. A lot of companies push the HFC back towards the X section to gain more power. They still keep the O2 sensor in the same position so it is before the cat. Some companies put the HFC in the primary cat position which retains O2 sensor functionality and does not throw a CEL (passes OBD II plug in emissions test). I know this from experience as I have passed the OBD II with the AA X-Pipe. Brands that put the HFC in the primary cat position that I know of are AA, ESS, and Gintani. Hope this helps. FWIW no aftermarket X-Pipe or test pipe will pass the "visual" portion of the emissions test.

As for relocating the O2 sensor, in theory it should work since the X-Pipes with the cat in the primary position seem to do just fine.

EnderG60 · 10-13-2015, 08:22 AM

Awesome, thanks for the info.

Has anyone done test pipes with the O2 relocated? I think this is the route I will go, but Im curious if there are issues moving the O2 sensor. Is the wiring long enough or is an extension cable needed?

pbonsalb · 10-13-2015, 08:48 AM

The rear 02 cable is short. There may be another version of the rear 02 with a longer cable, but you would have to do some searching around. You can cut and splice if you want; done right splicing works.

Many have complained that aftermarket cats in the primary cat position scrape. The stock cats are big but thin and most aftermarket cats are much thicker. Obviously this will be a bigger problem on a lowered car.

Most tuners sell an off road only version of the tune that preserves readiness. It is essentially an 02 simulator in the software.

EnderG60 · 10-13-2015, 09:11 AM

Aside from one post about the Evolve tune, I have seen completely zero about any company offering a way to maintain o2 sensor readiness. Can you point me to any reference that they offer that?

I would prefer to do things mechanically and correctly since I dont see much point in a $1000 tune that only yields 10 hp and stops a dash light coming on.

EnderG60 · 10-14-2015, 05:05 PM

I found a stock x-pipe with test headers local for cheap so Im gonna pick it up and try to relocate the rear O2's to behind the the secondary cats.

Well see how it works out.

oolas3 · 10-14-2015, 05:29 PM

Quote:

Originally Posted by EnderG60

I found a stock x-pipe with test headers local for cheap so Im gonna pick it up and try to relocate the rear O2's to behind the the secondary cats.

Well see how it works out.

Just to be clear are you relocating the rear o2s because you think it will put your car in readiness with the primary cats removed?

EnderG60 · 10-14-2015, 07:20 PM

thats the plan.

pbonsalb · 10-14-2015, 07:26 PM

Quote:

Originally Posted by EnderG60

Aside from one post about the Evolve tune, I have seen completely zero about any company offering a way to maintain o2 sensor readiness. Can you point me to any reference that they offer that?

I would prefer to do things mechanically and correctly since I dont see much point in a $1000 tune that only yields 10 hp and stops a dash light coming on.

Talk to the tuners. No one wants to post about illegal stuff. How do you think so many people with x pipes are passing? Again off road use only tune for your race car is the way it must be sold.

oolas3 · 10-14-2015, 07:42 PM

Quote:

Originally Posted by EnderG60

thats the plan.

There's no precedent that will work. You're going to need a tune. The test pipe/tune combo is well worth the price IMO. It's more than just hp improvements.

oolas3 · 10-14-2015, 07:44 PM

Quote:

Originally Posted by pbonsalb

Talk to the tuners. No one wants to post about illegal stuff. How do you think so many people with x pipes are passing? Again off road use only tune for your race car is the way it must be sold.

+1.

slowandfurious · 10-14-2015, 09:58 PM

Quote:

Originally Posted by pbonsalb

Talk to the tuners. No one wants to post about illegal stuff. How do you think so many people with x pipes are passing? Again off road use only tune for your race car is the way it must be sold.

Why would the tune be any more illegal than x pipes or test pipes? Vendors post x pipes and test pipes for sale all the time, I am sure with the understanding that it will be only used for offroad use.

EnderG60 · 10-15-2015, 06:38 AM

Quote:

Originally Posted by pbonsalb

Talk to the tuners. No one wants to post about illegal stuff. How do you think so many people with x pipes are passing? Again off road use only tune for your race car is the way it must be sold.

Why? The two tuners I talked to specifically mentioned they stop the CEL and disable the rear O2 sensors but can do nothing for readiness. I found what Im looking for, for a good price and for an extra $100 I can move the O2 sensors and see if it works.

If it does, yay Im still legal since I have a functioning cat and a computer thats not being tricked.

If not, Im out $100 and Ill shell out for a tune later.

At the end of the day, it all boils down to the fact Im an engineer, I like things done right not just easy and I cant leave crap alone.

pbonsalb · 10-15-2015, 06:50 AM

I like the idea of trying out relocation of the rear 02 to after the secondary cats. Let us know if it works.

Your experience with tuners is just one experience. Tuners can do exactly what I wrote they can do concerning simulating rear 02 so readiness passes and there is no CEL for increased or decreased emissions. They either won't do it for you or do not want the liability of doing it in general. Violating federal emissions law is serious and they cannot trust everyone and the blanket disclaimers about off road use are not always accepted.

M3 Number 86 · 10-15-2015, 05:33 PM

aren't there 4 o2 sensors in the rear?

pbonsalb · 10-15-2015, 07:13 PM

There are the 2 wideband 02 sensors for the ECU before the primary cats and the 2 narrow band 02 sensors for emissions monitoring after the primary cats. Four 02 in total; 1 wideband and 1 narrow band in each pipe.

EnderG60 · 10-16-2015, 07:45 AM

Quote:

Originally Posted by pbonsalb

I like the idea of trying out relocation of the rear 02 to after the secondary cats. Let us know if it works.

Your experience with tuners is just one experience. Tuners can do exactly what I wrote they can do concerning simulating rear 02 so readiness passes and there is no CEL for increased or decreased emissions. They either won't do it for you or do not want the liability of doing it in general. Violating federal emissions law is serious and they cannot trust everyone and the blanket disclaimers about off road use are not always accepted.

I can only confirm what I have been told directly from the tuners I have contacted.

I should have the x-pipe and test pipes next week, then I just have to figure out where to put the O2 sensors behind the secondary cats.

Just gata find some tubes to mount the sensors on now.

Mmn710 · 10-16-2015, 11:05 PM

I'm having the same issue. I'm stuck between test pipes or x-pipe. I'm leaning towards test pipes and just swapping when it's time for inspection (sucks but no choice). I ran O2 extensions on my 350z a while back and it worked. Wonder if it'll work for our cars.

10-13-2015, 07:26 AM	#1
EnderG60 Private First Class 45 Rep 184 Posts Drives: 2014 M5 / 2012 M3 Join Date: Oct 2015 Location: Atlanta Ga iTrader: (0)	Cat delete and x-pipe questions First off I am a noob but I have been searching for the past 2 weeks and still have questions I cant find answers to. I realize the primary 400 cel cats are the big restrictions and would like to remove them. I would like to retain the secondary (or aftermarket high flow) cats which appear to be 200 cel for both stock and high flow aftermarket and resonators so I can pass emissions and not have a gas smell. I see that all tunes only turn off the rear O2 sensor, which will stop the check engine light but wont pass the "readiness test" for emissions. I have heard the Evolve tune fixes this readiness issue but when I inquired about it I got no response. I also see that most aftermarket x-pipes have the O2 sensor bungs in the stock locations and the high flow cats after that which makes no sense to me, and O2 extenders probably will not work either. So Im left with these questions.... If I get test pipes like the Macht Schnell test pipes and the primary cat is removed correctly, can the stock cats be re-installed using the clamps that come with the test pipes? Has anyone tried relocating the rear O2 sensor behind the secondary cat? Or is there an x-pipe out there with high flow cats and the O2 sensors behind them? And if so has this worked for emissions?
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10-13-2015, 08:01 AM	#2
s14_kev Major 375 Rep 1,036 Posts Drives: E90 M3, E30 M3 Join Date: Sep 2012 Location: Bay Area, CA iTrader: (21)	RE: Test Pipes. Yes you can reuse the clamps to swap between OEM cats and test pipes. I have the OEM cat on my car with clamps. Just know that the seal may not be 100%. RE: X-Pipe with HFC. A lot of companies push the HFC back towards the X section to gain more power. They still keep the O2 sensor in the same position so it is before the cat. Some companies put the HFC in the primary cat position which retains O2 sensor functionality and does not throw a CEL (passes OBD II plug in emissions test). I know this from experience as I have passed the OBD II with the AA X-Pipe. Brands that put the HFC in the primary cat position that I know of are AA, ESS, and Gintani. Hope this helps. FWIW no aftermarket X-Pipe or test pipe will pass the "visual" portion of the emissions test. As for relocating the O2 sensor, in theory it should work since the X-Pipes with the cat in the primary position seem to do just fine. __________________ Akrapovic \| AngeliBright \| APEX \| Hankook \| IND \| JRZ RS1 \| Macht Schnell \| Mode Carbon \| Vorsteiner
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10-13-2015, 08:22 AM	#3
EnderG60 Private First Class 45 Rep 184 Posts Drives: 2014 M5 / 2012 M3 Join Date: Oct 2015 Location: Atlanta Ga iTrader: (0)	Awesome, thanks for the info. Has anyone done test pipes with the O2 relocated? I think this is the route I will go, but Im curious if there are issues moving the O2 sensor. Is the wiring long enough or is an extension cable needed?
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10-13-2015, 08:48 AM	#4
pbonsalb Lieutenant General 7679 Rep 13,759 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	The rear 02 cable is short. There may be another version of the rear 02 with a longer cable, but you would have to do some searching around. You can cut and splice if you want; done right splicing works. Many have complained that aftermarket cats in the primary cat position scrape. The stock cats are big but thin and most aftermarket cats are much thicker. Obviously this will be a bigger problem on a lowered car. Most tuners sell an off road only version of the tune that preserves readiness. It is essentially an 02 simulator in the software.
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10-13-2015, 09:11 AM	#5
EnderG60 Private First Class 45 Rep 184 Posts Drives: 2014 M5 / 2012 M3 Join Date: Oct 2015 Location: Atlanta Ga iTrader: (0)	Aside from one post about the Evolve tune, I have seen completely zero about any company offering a way to maintain o2 sensor readiness. Can you point me to any reference that they offer that? I would prefer to do things mechanically and correctly since I dont see much point in a $1000 tune that only yields 10 hp and stops a dash light coming on.
	Appreciate 0 Quote

10-14-2015, 05:05 PM	#6
EnderG60 Private First Class 45 Rep 184 Posts Drives: 2014 M5 / 2012 M3 Join Date: Oct 2015 Location: Atlanta Ga iTrader: (0)	I found a stock x-pipe with test headers local for cheap so Im gonna pick it up and try to relocate the rear O2's to behind the the secondary cats. Well see how it works out.
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10-14-2015, 07:20 PM	#8
EnderG60 Private First Class 45 Rep 184 Posts Drives: 2014 M5 / 2012 M3 Join Date: Oct 2015 Location: Atlanta Ga iTrader: (0)	thats the plan.
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10-15-2015, 06:50 AM	#14
pbonsalb Lieutenant General 7679 Rep 13,759 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	I like the idea of trying out relocation of the rear 02 to after the secondary cats. Let us know if it works. Your experience with tuners is just one experience. Tuners can do exactly what I wrote they can do concerning simulating rear 02 so readiness passes and there is no CEL for increased or decreased emissions. They either won't do it for you or do not want the liability of doing it in general. Violating federal emissions law is serious and they cannot trust everyone and the blanket disclaimers about off road use are not always accepted.
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10-15-2015, 05:33 PM	#15
M3 Number 86 Major General 3335 Rep 6,217 Posts Drives: black m3 Join Date: Mar 2015 Location: pasadena iTrader: (1)	aren't there 4 o2 sensors in the rear?
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10-15-2015, 07:13 PM	#16
pbonsalb Lieutenant General 7679 Rep 13,759 Posts Drives: 18 F90 M5, 99 E36 M3 Turbo Join Date: Feb 2011 Location: New England iTrader: (4)	There are the 2 wideband 02 sensors for the ECU before the primary cats and the 2 narrow band 02 sensors for emissions monitoring after the primary cats. Four 02 in total; 1 wideband and 1 narrow band in each pipe.
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10-16-2015, 11:05 PM	#18
Mmn710 Private First Class 27 Rep 164 Posts Drives: BMW E92 M3 Join Date: Aug 2015 Location: Long Island iTrader: (2)	I'm having the same issue. I'm stuck between test pipes or x-pipe. I'm leaning towards test pipes and just swapping when it's time for inspection (sucks but no choice). I ran O2 extensions on my 350z a while back and it worked. Wonder if it'll work for our cars.
	Appreciate 0 Quote