catalytic converter ??'s

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glyndon maryland
#1
My cats have failed. I am now debating on two things. Should take my existing sytem and cut the cats out and weld in straight pipes and then replace the sheilds to make it "appear" stock..........or should I put on a stock cat or high flow cats? If I convert it to striaght piping will it mess with my pre-cat oxygen sensors? I was thinking that it would because there would be a lot less back pressure and it would read more than normal and throw a check engine light. Any thoughts?? Anyone ever done this?? I have o2 sensor simulators on the post-cats sensors so I am not worried about them.........but I know you can't fake out the pre-cats sensors w/ simulators....or at least I haven't heard of anyone who has been able to. Cuz the simulators I have will not fake out the precat sensors. Let me know what you guys think
 
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Ames, IA / St. Paul, MN
#2
I suppose you could go catless without problems... assuming that the only O2 sensors you have is pre-cat. I doubt there will be any issues with the pre-cat O2s when having no cats is concerned.

High flow cats are nice if you want to remain legal...
 

grc

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chicago burbs
#3
why do you think the cats failed? if they really have failed, it is a symptom of the real problem, not the problem itself. if you don't fix the problem that caused these cats to fail, it will happen again.some people in areas that don't test used to just knock out the insides and put them back on. cheapest way and looks like they're still all there. of course the only correct advice is to replace them with new cats, stock, high flow or aftermarket replacement.
 
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glyndon maryland
#4
grc said:
why do you think the cats failed? if they really have failed, it is a symptom of the real problem, not the problem itself. if you don't fix the problem that caused these cats to fail, it will happen again.some people in areas that don't test used to just knock out the insides and put them back on. cheapest way and looks like they're still all there. of course the only correct advice is to replace them with new cats, stock, high flow or aftermarket replacement.

I know they failed because the car has over 135K on it and it is the original cat. Yeah I know about bashing the internals of the cat out.........but if I use a str8 pipe instead there will be no resistance of leftover core in there. And I am pretty sure I mentioned that I was ganna re attach the sheilds so the cats would "appear" to be there and all
 
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Adana/Turkey
#5
I did this on my 96 320I (European Only). It had one pre-cat O2 sensor. I removed the cat, left the sensor intact, drove the car 90k miles more, and had no problems what so ever. Do put in a straight pipe instead of leaving a hollow shield down there because it might emmit a tinny, somwhat unpleasant sound.
Hope I am not late with this.
 
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San Diego
#7
e36325is said:
if you remove your cat, is there anyway to pass emissions?

not counting on the additives you put in your tank?
Just replace the converter--aftermarket versions cost $100-200 and work well. Forget any additives for your smog test. just make sure the car is tuned up and running right. Most all cars have exhaust systems "designed" to have a converter and if removed will often run worse if the converter is removed. In addition new cars have OBD systems that will report a fault in teh computer if the converter is removed.

Steve
 


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