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Mostly Harmless
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1,540 Posts
One of our local guys failed with the FM cat, swapped in a Magnaflow direct fit and passed. That was the only change made.
Your issue might well be the cat, yes.
 

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Supporting Member
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210 Posts
if you and your neighbors can stand the noise and smoke, do it.
After some more reading, some people are saying that seafoaming could ruin/clog your cat because all this gunk is coming out of your engine all at once. Is there a technique that I can use such that it won't put as much of a strain on my cat? It's supposed to be relatively new so I don't want to trash it. Thanks!

Are you using a Universal/high flow Cat? Or do you have a obd CA specific cat? Have you tamperd with your AFM? With the High NO's this is definately your cat. Buy the CA OBD cat and your problems will be solved. CA cats about $100 more than the regular cats but it will get you to pass smog.
What is a OBD cat? As in on-board diagnostics? I can check whether the cat is a CA-legal cat or not. Would a CA-legal cat perform much better than a regular cat would? Thanks!
 

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Cat Jesus
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4,078 Posts
Hey guys!

Here is how my smogs have been up to today:

06/2007
*Bought my car, did a tune up and did a smog. FAIL. The cat ended up being hollow.
(Can't find paperwork ATM)

*Threw a new cat (universal weld-in, pre CA legal cat era) on and passed with flying colors.
M1: 15mph @1914rpm %CO2:14.5 %O2:0.0 HC:134/32 CO:0.82/0.03 NO:847/26 PASS

M2: 25mph @2215rpm %CO2:14.4 %O2:0.0 HC:108/13 CO:0.71/0.07 NO:786/11 PASS


06/2009
*No tune up before testing, timing was advanced to ~14 degrees and same cat. Passed.
M1: 15mph @2010rpm %CO2:14.7 %O2:0.3 HC:134/104 CO:0.82/0.12 NO:847/305 PASS

M2: 25mph @2256rpm %CO2:14.8 %O2:0.3 HC:108/41 CO:0.71/0.13 NO:786/84 PASS


06/2011
*No tune up, no oil change, same timing same cat. FAIL. My NoX numbers were 2x and then some above the max.
M1: 15mph @1905rpm %CO2:13.1 %O2:2.6 HC:134/100 CO:0.58/0.02 NO:847/2300 GROSS POLLUTER

M2: 25mph @2141rpm %CO2:12.7 %O2: 3.0 HC:76/81 CO:0.49/0.02 NO:786/1870 GROSS POLLUTER

*It ended up being the cat. Got it replaced (Magnaflow 36684, OBD-II CA cat, cat physically longer than universal weld-in), ran down the freeway and got it tested. Passed with VERY low NoX numbers. Also had an exhaust leak that was repaired that is why the O2 is lower haha. It was before the cat.
M1: 15mph @1887rpm %CO2:14.0 %O2:1.5 HC:134/21 CO:0.58/0.02 NO:847/3 PASS

M2: 25mph @2215rpm %CO2:14.4 %O2:1.7 HC:76/8 CO:0.49/0.02 NO:786/4 PASS
 

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Supporting Member
Joined
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210 Posts
Hey guys!

Here is how my smogs have been up to today:

Bought my car, did a tune up and did a smog. FAIL. The cat ended up being hollow. Threw a new cat on and passed with flying colors.

2 years later
Tune up, timing was advanced to ~14 degrees and same cat. Passed.

2 more years later (this past week)
No tune up, no oil change, same timing same cat. FAIL. My NoX numbers were 2x and then some above the max. It ended up being the cat. Got it replaced, ran down the freeway and got it tested. Passed with VERY low NoX numbers.

Do you guys want me to post up numbers?
Sounds great! Could you post before and after numbers? You can use my template use the CODE tags if it helps you :)
 

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Speed Tribe OG Member
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4,628 Posts
This is very common if you bought a Cat about 2-3 years ago. All the cats back then were rubbish, and only good for a few months.

just make sure you buy a CA cat. Those universal ones are worthless. Trust me. I know.
 

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Supporting Member
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210 Posts
This is very common if you bought a Cat about 2-3 years ago. All the cats back then were rubbish, and only good for a few months.

just make sure you buy a CA cat. Those universal ones are worthless. Trust me. I know.
All the cats from 2-3 years ago were bad? Why?

Got to smog my car by the 18th and im nervous. Just recently installed a RB exhaust with an OEM cat from 2ndchanceroadster. Im hoping this will be enough to get me to pass...or else I have to cough up some cash.
How much did you get your cat for from 2ndchanceroadster?
 

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Registered
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660 Posts
Son of a bitch... 2 years ago, in order to pass, I put in a new Magnaflow 2.25" high flow cat, as well as a new Bosch oxygen sensor. Lately I've been having the oxygen sensor bring up the CEL.

Did a training run today, how the **** did my car foul both the oxygen sensor and cat in only 2 fucking years?!

Any clue?

 

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Registered
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831 Posts
Before, see previous post:
15mph (Max/Meas), CO2 14.74, O2 0.12, HC 93/85, CO 0.39/0.28, NO 504/1269
25mph (Max/Meas), CO2 14.85, O2 0.01, HC 59/28, CO 0.39/0.24, NO 542/584


Today, everything stays the same except new OEM CA-spec magnaflow bolt-on cat:
15mph (Max/Meas), CO2 14.72, O2 0.00, HC 93/10, CO 0.39/0.01, NO 504/365
25mph (Max/Meas), CO2 14.81, O2 0.00, HC 59/8, CO 0.39/0.00, NO 542/6
 

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Mostly Harmless
Joined
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1,540 Posts
Thanks for the follow-up post!

Just changed out my cat of unknown origins (part number comes up with a hit for a Cherry Bomb cat...weird) with a Magnaflow direct fit. Will see how far that brings down my NOx numbers.
 

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Registered
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55 Posts
Hey guys, I posted this in the wrong section and have been referred here, so i'll just repost:

1990 NA~178k miles, I legally passed smog last year, but cut it a little close:

So I tried to smog my car last week (registration due this Friday!), and things are horrible~ I went in and failed miserably the first time, so then I changed out the spark plugs, threw on a new O2 sensor and changed the oil to see how it would do on the re-test... almost no change! I've been told that changing th cat will most likely not get me to pass smog and I was wondering if you guys have any idea what I should try and fix? OOooo, and she is bone stock~ I feel like just selling her at this point, let the new owner know the issues, le sigh~

Here are the numbers before and after the new O2 sensor etc. Wicked horrible~



HC
15mph
max: 134
measured: 196 (2nd Test: 198)

25mph
max: 108
measured: 164 (2nd Test: 173)
CO
15mph
max: 0.82
measured: .080 (2nd Test: 0.85)

25mph
max: 0.71
measured: 0.78 (2nd Test: 0.88)

NOx
15mph
max: 847
measured: 2337 (2nd Test: 2159)

25mph
max: 786
measured: 1777 (2nd Test: 1593)
 

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Registered
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4 Posts
i have failed twice now as well. my issue may be that the car was stored for 3 years, never driven (barely started) iv changed plugs, wires, fluids, ran sea foam, used crc guaranteed to pass smog formula....and failed twice...marginally both times on nox....
pretty desperate at this point, as i have been riding dirty for month and half now..with 08 stickers...and expired dmv "7" in window.
im convinced its my cat, bee-buzz rattle from under car rolling. i havnt looked into summit yet but that ebay # few posts above results in no more cats avail. from that seller. HELP :)
 

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Registered
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77 Posts
i have failed twice now as well. my issue may be that the car was stored for 3 years, never driven (barely started) iv changed plugs, wires, fluids, ran sea foam, used crc guaranteed to pass smog formula....and failed twice...marginally both times on nox....
pretty desperate at this point, as i have been riding dirty for month and half now..with 08 stickers...and expired dmv "7" in window.
im convinced its my cat, bee-buzz rattle from under car rolling. i havnt looked into summit yet but that ebay # few posts above results in no more cats avail. from that seller. HELP :)
Replace the Cat, pronto. If you continue to fail after doing all you've done at this point, you can usually boil it down to the cat. Your symptoms make that an even greater possibility, though a "bee-buzz" can mean a small exhaust leak at a flange or crack as well. Get the car up on stands, tear the exhaust down from downpipe back and inspect everything.
 
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