Catalytic convertor question.

[iwannadie]

I just found out that my catalytic convertor was on backwards(thanks PO) and has been that way for like, 8 years. I honestly never noticed the orientation arrows until I took it off and went to put it back on. I have never had problems with emission testing until recently my NoX levels were high but still within passing. Would the direction of the cat be the cause of my high NoX?

Is the cat damaged now from being run backwards or was it simple not as effective with the flow going into the wrong side? Can I just throw it back on correctly and be good with emissions or will reversing the flow after so long cause any clogging problems?

Lastly, would having the cat backwards have killed any of my awesome NA power(flow issues) or, is it just a matter of burning off gases effectively and the flow remains the same?

 

[A. Jay]

I just found out that my catalytic convertor was on backwards(thanks PO) and has been that way for like, 8 years. I honestly never noticed the orientation arrows until I took it off and went to put it back on. I have never had problems with emission testing until recently my NoX levels were high but still within passing. Would the direction of the cat be the cause of my high NoX?

Is the cat damaged now from being run backwards or was it simple not as effective with the flow going into the wrong side? Can I just throw it back on correctly and be good with emissions or will reversing the flow after so long cause any clogging problems?

Lastly, would having the cat backwards have killed any of my awesome NA power(flow issues) or, is it just a matter of burning off gases effectively and the flow remains the same?

"Some newer systems do not employ air injection. Instead, they provide a constantly varying mixture that quickly and continually cycles between lean and rich to keep the first catalyst (NOx reduction) from becoming oxygen loaded, and to keep the second catalyst (CO oxidization) sufficiently oxygen-saturated" - Wikipedia

Based on that, your NOx levels would be affected by incorrect orientation. Flow is the same (N/A power was not held back lol), and since that page doesn't mention it in the ways that converters get damaged, your converter should be fine.

 

[Cz.]

I would think that your converter is fine regardless of how it was oriented. I've only dealt with a few cats before, but the ones I dealt with were not directional.

8 years is a pretty long time for a cat anyways, it may simply be on its way out.

 

[iwannadie]

Thanks for the replies. I was worried versing the flow might have caused clogging or ruined it but seems like thats not an issue. I also secretly hoped the reverse flow stole some awesome NA power ; p .

I am due for emissions testing in 1 1/2 years so if I fail then I will go with the new cat then since I passed so easy last time(except the NoX being close).

 

[Poodles]

Depends on the design of the cat, if it's a single or multi stage. It's not going to "steal" power as on a dyno the difference between a cat and a test pipe is within the margin of error of the dyno...unless it's clogged of course.

NOx is handled through EGR for the most part though.

 

[iwannadie]

Depends on the design of the cat, if it's a single or multi stage. It's not going to "steal" power as on a dyno the difference between a cat and a test pipe is within the margin of error of the dyno...unless it's clogged of course.

NOx is handled through EGR for the most part though.

I know a cat in good working order doesn't cause enough restriction to be of any concern. I was worried that reversing the flow of it would have caused issues. Kinda like vacuum hoses that only allow air to go one way...

 

[Poodles]

Nope, most aftermarket cats are a grid, won't matter direction.

 

[erags1092]

i have question about cats. will the car run fine without the cat? i have a 90 NA i dont have any sensors or anything going to it. my emissions will go up but who really cares lol. thanks

 

[A. Jay]

i have question about cats. will the car run fine without the cat? i have a 90 NA i dont have any sensors or anything going to it. my emissions will go up but who really cares lol. thanks

I care, but that's another issue.

Anyways, to answer your question, yes. In 1996 OBDII became a standard on all cars (in the US as far as I know), and part of that requirement was to have a oxygen sensor before and after the first (actually, I have yet to see a 1996+ car with more than one) set of cats, which creates problems when removed. Most (including supras), if not all pre '96 cars only have one sensor before the cat(s), so removing them wouldn't affect the sensor(s)'s readings.

Now, will it be an upgrade? ...

Depends on the design of the cat, if it's a single or multi stage. It's not going to "steal" power as on a dyno the difference between a cat and a test pipe is within the margin of error of the dyno...unless it's clogged of course.

NOx is handled through EGR for the most part though.

... No, not really.


Edit: Btw, the car will get louder. Just letting you know.

 

[erags1092]

koo thanks

 

[Nick M]

"Some newer systems do not employ air injection. Instead, they provide a constantly varying mixture that quickly and continually cycles between lean and rich to keep the first catalyst (NOx reduction) from becoming oxygen loaded, and to keep the second catalyst (CO oxidization) sufficiently oxygen-saturated" - Wikipedia

Hmmm, somebody that isn't full of it contributed to a wiki article. This is sort of correct. That is the old way. That is why your oxygen sensor switches. It is supposed to do it. Newer cats are made to work with A/F sensors, or what most of you call a wideband.

 

[RazoE]

I care, but that's another issue.

Anyways, to answer your question, yes. In 1996 OBDII became a standard on all cars (in the US as far as I know), and part of that requirement was to have a oxygen sensor before and after the first (actually, I have yet to see a 1996+ car with more than one) set of cats, which creates problems when removed. Most (including supras), if not all pre '96 cars only have one sensor before the cat(s), so removing them wouldn't affect the sensor(s)'s readings.

Now, will it be an upgrade? ...



... No, not really.


Edit: Btw, the car will get louder. Just letting you know.

CA N/A's have 2 02 sensors..