91 NSX Manual Smog Limits Changed?

M

mrbythatmuch

Contributing Member
Joined
31 December 2004
Messages
119
Location
San Diego,CA
So my car failed smog check today on high NO. So I went home and looked at my past results. The Max limits for a 91 manual have changed???

The max NO used to be 785/724 (15/25 mph) now its 549/507 :confused:

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=22427

If you have a 92 or an automatic the numbers haven't changed

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=22428

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=23345

Anyone else run into this yet?
 
really? my car was just smogged and it passed, but its completely stock... let me check the limits... that's BS if they just up and changed it on us...

are you modded?
 
comptech?

i just checked and yeah, the NOx limits are the same as yours...
 
wow, this is BS... they are pretty much cracking down on old cars. :mad:
 
what about classic cars ?
 
mrbythatmuch said:
So my car failed smog check today on high NO. So I went home and looked at my past results. The Max limits for a 91 manual have changed???

The max NO used to be 785/724 (15/25 mph) now its 549/507 :confused:

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=22427

If you have a 92 or an automatic the numbers haven't changed

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=22428

http://www.autorepair.ca.gov/pubwebquery/cutpoints/ShowResult.aspx?VLTROWID=23345

Anyone else run into this yet?
Click to expand...

I hope for ur sake that u failed a PRE-TEST and not the real one.

When I failed the "real" test on the FD and truck, both of them had to get smogged EVERY year instead of EVERY OTHER YEAR. Motivated me to sell the vehicles.

BTW, do u guys have access to "Clean Power" at ur local speed shops? It looks like moonshine and smells like paint thinner. 32oz bottle is around $25.

it changes the gasoline at a molecular level.

When I pour this in my exhaust had less smell and in both my trucks (one with 150k miles and the other with 21k miles) I was able to pass smog like a near zero emission vehicale. All of my readings were ZERO and just 6PPM on the NOx levels.

The smog technician was scratching his head and was wondering if the sniffer fell outta the tail pipe. LOL. Tears were rolling outta my eyes as I was witnessing all of this.
 
Last edited:
sucks for you cali dudes with older nsx's :mad:
 
HBui39 said:
comptech?

Yup I'm fully CA smog legal parts wise.

I just checked and yeah, the NOx limits are the same as yours...
Click to expand...

Which ones? When was the test? What year is your car and is it manual?

I fired off an email to BAR (Bureau of Automotive Repair) and actual got a response. They asked for my license plate so they could look into it.
 
i have a 91 manual as well. the test was like a month ago. HC and NOx limits were reduced 30% from what i can tell. they sneaked this in without anyone knowing or caring apparently. its been this way since 2010.

that sucks Comptech headers wont pass, i was looking forward to getting it. have you tried contacting Comptech? CARB isn't going to do anything but tell you that these are the new standards and you have to deal with it. I hope that I'm wrong though.
 
Seriously, if the car isn't passing smog something is wrong with it, or the tech didn't have the cats hot enough during the test. Headers will not affect the numbers much, if at all. Even these reduced limits ought to be like limbo dancing under a goal post. My last test was after the car sat for a long time with the battery unhooked. I drove it straight to the smog shop up the street, and it passed at about 1/2 those limits for NOx. I've seen it test in the single digits.
 
I have a smog test needed this month :frown: !! I hope I don't have any issues.

I will post my results and numbers.

It might just be a change for your county...but that's just a speculation at this point. Let us know what you find out.
 
My car also failed smog for that exact parameter. One shop said to consider the EGR. Another said to just run the engine for an hour and then drive straight to the test facility with it hot.
 
Aww damnit. I barely passed in '09 and need to smog this year and I'm running comptech headers and exhaust. Has anyone else tried this "Clean Power" gas solution?
 
Last edited:
my NOx readings are up in the 400's... and my car is stock. it passed, but not by much. they say the average is in the 200's... i wonder if anyone is even close.
 
c30na1 said:
Aww damnit. I barely passed in '09 and need to smog this year and I'm running comptech headers and exhaust. Has anyone else tried this "Clean Power" gas solution?
Click to expand...

you barely passed in 09? that was before they lowered the limits.... you may have bigger problems than passing smog.
 
HBui39 said:
my NOx readings are up in the 400's... and my car is stock. it passed, but not by much. they say the average is in the 200's... i wonder if anyone is even close.
Click to expand...

Not for a 20 year old car!!! With new o2 sensors and plugs, mine was around 400's as well (stock).
 
From "Bareditor@DCA" <[email protected]>
After researching your issue, the pass fail cut points for your 1991 manual transmission Acura NSX are correct. The cut points were recently revised for this vehicle while the cut points for the other years of the same model have not been revised. BAR routinely evaluates the pass fail criteria and we may adjust the points to reflect the state of the fleet. In your situation the number of 1991 Acura NSX vehicles produced is significantly higher than any other year and allows BAR to more accurately evaluate the state of that specific year and adjust the pass fail cut points. After reviewing your specific emissions results I find that the NOx is significantly higher than the average for the same vehicle. BAR offers an average passing emissions web application so motorists can see the average passing emissions of other like vehicles for the most recent 3 calendar quarters. I have inserted the table below for your information. As you can see, the NOx emissions of your vehicle are significantly higher than the averages from the last 3 calendar quarters. You will need to have the reason for the elevated emissions diagnosed and repaired in order to pass the required smog check.

Query was executed on 7/19/2011 7:17:00 AM Model Year Make Model 1991 ACURA NSX YEARQUARTERTESTCYCLE MODELYEARHC5015 CO5015 NO5015HC2525 CO2525 NO2525 2011 2 A 1991 55 0.16 306 33 0.12 227

YEARQUARTERTESTCYCLE MODELYEARHC5015 CO5015 NO5015HC2525 CO2525 NO2525 2011 1 A 1991 55 0.16 303 32 0.11 226

YEARQUARTERTESTCYCLE MODELYEARHC5015 CO5015 NO5015HC2525 CO2525 NO2525 2010 4 A 1991 53 0.16 302 32 0.12 231
 
SmogSearch.com said:
http://www.smogsearch.com/index.php?page=faq]Nitrogen[/url] Oxides (NOx)*
NOx is formed inside the combustion chamber when excessive heat is present.

A list of common causes of NOx related smog check failure:

1. As usual check the timing first. Advanced timing can cause extra NOx.

2. The next thing to check is the EGR system.This system is designed to reduce Nox. It consists of a EGR valve, vacuum hoses, one or more vacuum switching valves or solenoids. Its job is to reroute a small amount of exhaust gas back into the engine to help reduce combustion chamber temperature. Not all vehicles have an EGR system.

3. Next thing to check is the air / fuel ratio. If the vehicle is running to lean, NOx emissions will increase.

4. Some possibilities are a restricted fuel filter, low fuel pressure, vacuum leaks, oxygen sensor, load sensor such as a map sensor, air flow meter.

5. Check the cooling system. An extra increase in water temperature will increase NOx production.

6. A defective catalytic converter can also increase NOx. The Cat. reduces NOx that has already been produced.

7. Check to see that the air coming into the engine is not over heated. Some vehicles have a vacuum controlled air valve which switches the incoming air to hot air from the outside of your exhaust manifold.This should only happen when the engine is cold. If this system malfunctions and sends hot air all the time.Your Nox could go up. This system is called T.A.C. ( Thermostatic air cleaner )

8. There is another system similar to the one above called E.F.E. ( Early fuel evaporation ). This system routes hot air under the intake manifold. This helps keep the fuel in the vapor state. If stuck in the hot mode Nox emissions could increase and cause a Smog Check failure.
Click to expand...

If the CATs have never been changed, they're probably bad. I would look into getting a new set. This is common on the NSX for earlier models.
 
HBui39 said:
you barely passed in 09? that was before they lowered the limits.... you may have bigger problems than passing smog.
Click to expand...

Just took it to my friends smogshop and ran a test smog run. The NOx was iffy around 15mph, but fine at the other speeds. From what he showed me on the computer, for a 92, i believe 770 ppm was allowed.

I'll change the spark plugs and use some lucas oil fuel additive and try another test run next month.

If that doesn't bring down the NOx, replace the O2 sensors(which starts getting pricey).

If that fails, time to register in Nevada.

btw, I currently have ~80k miles.
 
c30na1 said:
Just took it to my friends smogshop and ran a test smog run. The NOx was iffy around 15mph, but fine at the other speeds. From what he showed me on the computer, for a 92, i believe 770 ppm was allowed.

I'll change the spark plugs and use some lucas oil fuel additive and try another test run next month.

If that doesn't bring down the NOx, replace the O2 sensors(which starts getting pricey).

If that fails, time to register in Nevada.

btw, I currently have ~80k miles.
Click to expand...

oh yeah, 92's still have higher limits... for now.
 

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