Comparing Emissions Test Results

I have had to get both of our 1.6 Miatas inspected in the last few weeks and found the results interesting...

Description | Limit | 93LE | SC 92
25 mph HC | 160 | 27 | 2
15 mph HC | 166 | 110 | 9
25 mph CO | .90 | .26 | .02
15 mph CO | .93 | .42 | .09
25 mph NOx | 1179 | 556 | 22
15 mph NOx | 1304 | 1304 | 69

First, it looks like the 93 may have some issues next year with NOx. Stevan suggested I check the timing for that. More importantly, look how drastically low the supercharged car's results are when compared to the stock 93LE. I have to wonder if the programmable ECU has allowed me to tune it to run so much cleaner at cruise than the stock ECU.

or the cat is newer

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Originally Posted by goofygrin

or the cat is newer

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I actually bought the current CAT used a few years ago. I had been running a high flow CAT that I picked up used but got sick of the noise so went back to a stock one. I wish I had saved all of my inspections so I could see how the numbers have changed with the 3 different CATs on the car and with and without the LINK ECU. I think I still have some of them, but I don't think I could figure out when the changes to the car occured.

Interesting comparison. I'll see if I can dig out last year's results for the 90 & 94. I remember thinking the 90 had an exhaust leak because the numbers seemed very low.

Have you ever Seafoamed the 93?

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Originally Posted by cwisenheimer

Have you ever Seafoamed the 93?

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Nope. The 92 was seafoamed 3 or 4 years ago.

Cheap and easy way to get those emissions out all at once. :-)

Too bad mosquito season is already over.

timing was the answer on my nox issue earlier this year. 95 with newish cat and recent rebuild. set it back to factory and passed with flying colors

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Originally Posted by Titus

I have had to get both of our 1.6 Miatas inspected in the last few weeks and found the results interesting...

Description | Limit | 93LE | SC 92
25 mph HC | 160 | 27 | 2
15 mph HC | 166 | 110 | 9
25 mph CO | .90 | .26 | .02
15 mph CO | .93 | .42 | .09
25 mph NOx | 1179 | 556 | 22
15 mph NOx | 1304 | 1304 | 69

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Got the '94 on some rollers this morning. Using your same format, here's last year vs. this year:
Description | Limit | 2009 | 2010
25 mph HC | 160 | 65 | 27
15 mph HC | 166 | 107 | 45
25 mph CO | .90 | .23 | .22
15 mph CO | .93 | .26 | .21
25 mph NOx | 1179 | 356 | 404
15 mph NOx | 1304 | 525 | 600
Differences in the car are a Monsterflow intake I got from wags, as well as a timing bump and new o2 sensor.

...and for the '90 (can't find my '08 numbers)...
Description | Limit | 2007 | 2009 | 2010
25 mph HC | 206 | 69 | 66 | 18
15 mph HC | 212 | 116 | 158 | 27
25 mph CO | 1.33 | .51 | .04 | .02
15 mph CO | 1.20 | 1.14 | .65 | .03
25 mph NOx | 1512 | 8 | 349 | 349
15 mph NOx | 1657 | 108 | 1013 | 429
I futz with the timing a bit before inspection on this car each year. All things considered, not bad.

Cool... interesting how your 15mph NOx on the '90 shot up in 2009 and back down in 2010.

I got the '93 inspected for 2011. The only thing that has changed in the car since last year was running a bottle of RXP through it the tank before the inspection at the recommendation of Rogue.

Description | Limit | 93LE ('10) | 93LE ('11)
25 mph HC | 160 | 27 | 85
15 mph HC | 166 | 110 | 61
25 mph CO | .90 | .26 | .37
15 mph CO | .93 | .42 | .37
25 mph NOx | 1179 | 556 | 696
15 mph NOx | 1304 | 1304 | 856

I actually just got my '94 inspected yesterday. I will post it up when I get home. I haven't looked at the numbers but the guy said my NOx was high and I almost didn't pass because of it.

Description | Limit | 94m
25 mph HC | 153 | 33
15 mph HC | 159 | 52
25 mph CO | .86 | .09
15 mph CO | .89 | .13
25 mph NOx | 1123 | 720
15 mph NOx | 1242 | 1217

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Originally Posted by Titus

look how drastically low the supercharged car's results are when compared to the stock 93LE. I have to wonder if the programmable ECU has allowed me to tune it to run so much cleaner at cruise than the stock ECU.

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Look at trey's green glory hole, i will put money on the line that it runs cleaner with out a cat at cruse the a stock miata just from all the extra spark added and fuel removed for the cells used at cruse. Going to be doing the same with the DD and track car as soon as MS2 comes in the mail.

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Originally Posted by jeff_man

Look at trey's green glory hole, i will put money on the line that it runs cleaner with out a cat at cruse the a stock miata just from all the extra spark added and fuel removed for the cells used at cruse. Going to be doing the same with the DD and track car as soon as MS2 comes in the mail.

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It passed an inspection on the sniffer with no cat last year. However, I still have to be carefull about where I take it because I assume that anyone who opens the hood is going to get nervous. On the sniffer, it does just fine. However any oscillation in the idle will make it fail, bad.

Cruise is another story. I'm running it at 16.0:1 in cruise so it would definitely fail unless I ran the "inspection friendly" fuel and spark table. My normal table runs 16.0:1 and ~40* advance in cruise, the "inspection friendly" table runs 14.7 and ~28* in cruise. That's why I get 34mpg in the track car and 24 in the daily.

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Originally Posted by mr brg

Cruise is another story. I'm running it at 16.0:1 in cruise so it would definitely fail unless I ran the "inspection friendly" fuel and spark table. My normal table runs 16.0:1 and ~40* advance in cruise, the "inspection friendly" table runs 14.7 and ~28* in cruise. That's why I get 34mpg in the track car and 24 in the daily.

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Thought at cruise lean and lots of spark would be "cleaner" as your running more efficiently therefor getting better gas mileage and less emissions.

I just failed, and failed HARD Here are last year's numbers and this years. Actually thought I was going to to better-- Had the timing belt done (apparently i was off a tooth) and there put on Bnordin's old jackson racing Cat.


Description | Limit |'10 | '11 Test
15 mph HC | 212 | 91 | 205
25 mph CO | 1.33 | .20 | .23
15 mph CO | 1.2 | .66 | .45
25 mph NOx | 1512 | 966 | 1569
15 mph NOx | 1657 | 1647 | 3092


My NOx is what is killing me, and the 15 MPH is off the chart. Went by Track Dog today and William Seafoamed the shit out of it, hoping to take it back next week for a retest. Might Try a dose of RXP before the next test........

have you replaced your 02 sensor? That could be the problem. I would totally put in something in the fuel to help lower the NOx. Goood luck and let us know if it's any better the second time.


Strider

Do people get 1 free test in the next 15 days or unlimited (I've never failed)? Also, keep your receipts. Does TDR count as a certified emissions repair shop? Sorry to hear about it.

Giving life to an old thread.
I failed today on the nox (in the 2000s). Get to take it back as many times as it takes within 15 days. Guess I'll try some rxp and see what it does.