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09-29-2010LAST POST
Just about to pull the trigger on a HFC X-pipe. Either AA or Gintani. My question is when my OBD2 readiness test comes up, can I pass? Obviously my CEL light has to be operational. Now when I take off the rear cats for resonators and turn off the rear O2 sensors is that gonna pass? Of course my primary O2 has to be functional. I also heard that you could put spacers on the O2 to pull them a little bit out of the exhaust stream. This should help keep CO2 down, this is what I heard. Anybody have any insight? Pass or not, suggestions?
If you turn off the rear O2 you will fail a readiness test
J08M3 wrote
If you turn off the rear O2 you will fail a readiness test
+1
Ok, then how does it work when you elliminate rear cats for resonators? Is there a place to put the rear O2 sensor? Will they not throw a code? I guess you tune and rise the CO2 threshhold on the rears? Thanks for the responces. I just want to make sure I make the right decision, buy the right parts and have my tune set-up the right way so I have no issues. If it cant be done then I understand and will not get involved in this modifacation.
jimmy ny wrote
Ok, then how does it work when you elliminate rear cats for resonators? Is there a place to put the rear O2 sensor? Will they not throw a code? I guess you tune and rise the CO2 threshhold on the rears? Thanks for the responces. I just want to make sure I make the right decision, buy the right parts and have my tune set-up the right way so I have no issues. If it cant be done then I understand and will not get involved in this modifacation.
When you eliminate rear cats, your emissions are unaffected. The rear cats are not OBD-II compliant and not used for emissions reasons. Only the primary cats are what are monitored by the O2 sensors hence why there are 2 sets. One before the primary cat and one after. The O2 sensors compare readings to determine whether you are emissions compliant. The only way to pass emissions testing for sure is to not touch the primary cats. Once you do, there is always the problem of not passing emissions testing. In regards to using a tune to raise the threshold of the o2 sensors. This is such a gray area that most companies cannot do, say they can do it-but cannot, or can and it is still hard to confirm.
Without rear cats you will fail a visual and you may fail a sniffer, but it won't trigger an SES light.
FStop7 wrote
Without rear cats you will fail a visual and you may fail a sniffer, but it won't trigger an SES light.
No sniffer in ny and they never do a visual plus if you're not a BMW tech you'd never know there were supposed to be secondary cats.
Great so I guess i can get by with the rears deleted. Hope the primarys dont throw a code. Is there a big difference between 200 and 300 cell cats? Smog that much higher, smell difference? Do i need the O2 spacers? Will have a tune but still have to pass readiness to CEL will be functioning.
1MORELAP wrote
In this post Mike describes how to pass emissions with primaries removed.

Its not easy, but doable.

http://www.m3post.com/forums/showthread.php?t=434955

Tomasz
To pass emissions without a specialized tune is pretty much impossible. Let me explain. If you have no cats, you will throw a CEL farily quickly. Once you do, you can clear it, but that also turns off your readiness, so it takes anywhere from 100-150+ miles before the readiness is set back to on again. Without any cats, you will definitely code again before you set readiness. I know people that can't even set their readiness again after clearing codes with 200 cell cats.
jimmy ny wrote
Great so I guess i can get by with the rears deleted. Hope the primarys dont throw a code. Is there a big difference between 200 and 300 cell cats? Smog that much higher, smell difference? Do i need the O2 spacers? Will have a tune but still have to pass readiness to CEL will be functioning.
If you do not touch your primaries, you will pass emissions fine even without a tune. Most of the aftermarket cats out there are 200 Cell, Akropovics are 100 Cell and the OEM are 400 cell if I am not mistaken. You will definitely notice a smell with no cats. I have 200 cell cats and I still get a smell. You will not need O2 spacers if you do not touch your primary cats.
When I tried to pass emissions I first had to take off my Dinan xpipe and the put my stock xpipe back on. I was also running the Dinan stage 2 software, which does not disable the SES light, so it would light up when you started the car. With the stock xpipe when to get tested and fault codes were stored, catalyst below threshold both banks. OK, cleared the codes drove 150 miles and then retested. At this point the car would not pass due to failing readiness test. So in order for me to pass emissions I then had to go to Dinan stage 1 software, drive for about 25 miles ( to reset readiness) and then retested, which I passed. Long story short, as Ben said, changing your cats and running a Stage 2 software will not pass.
Well i was going to run the Gitani 300Cell HFC. I was hoping that they would get by with a tune and maybe some O2 spacers. But if i cant pass, then well I guess I have to leave that power on the table and say forget about it.