help with smog

[willabeest]

1992 NSX CT headers otherwise stock engine with 110K
NO 795 (failed). pass was 785 at 15 MPH
everything else looks good
i had the car idling before the test for 20 minutes
is it possible the engine was too warm?
i have one free test since i failed, should i go back and maybe test it again and not let it idle?
very confusing.
thank you.

 

[nsxnut]

You want the cats HOT the hotter the better. Cats work when they are hot not cold.
I drive the car on the Freeway for 20 min not idle.

You can use 100 octane gas to help reduce NO2 but it will increase HC a bit.

Make sure your EGR valve is functioning properly not sure it will be a factor at 15 mph?


Later,
Don

 

[willabeest]

according to almost everything i read online NO emissions are increased if the engine is running hotter than it should.
seems to me, hotter the better for everything except NO.
i was so surprised by this, i kept looking and looking, and kept finding the same info on NO.
example

The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F.

By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures.
http://www.smogtips.com/failed-high-NO-nitrous-oxide.cfm

 

[Daedalus]

Get the cats hot so they work right, and let the EGR and cooling system (and normal closed loop operation) take care of NOx. The cats reduce NOx, HC and CO.
E.g.: 6NO2 + 4HC + 2CO --> 2H20 + 6C02 + 3N2
Combustion temps shouldn't be too crazy during a smog test @ 15mph in 2nd gear!

I've posted in another thread that I hook up my vac gauge to the EGR before smogging the car, just to make sure the EGR is working. If it isn't, then I already know where to start. You can also try using Water Wetter. I've not had to use it myself, but the theory is sound. It increases heat transfer to the coolant in the heads, and then to the radiator, so combustion temps should drop.

 

[willabeest]

there is a good test of water wetter on TTAC, it did not reduce temps if used with antifreeze (although it does work with water).
EGR prime suspect now.

 

[BATMANs]

This is what I would do (which has helped me pass borderline cases like this):

Run a bottle of for the almost a full tank and then towards the end before filling up go smog the NSX:

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If that doesn't work then this will work 90% of the time (unless ur car is way outta whack with some part failure or bad tune):

http://www.nsxprime.com/forum/showthread.php/154063-Smog-Test-2-(Fail-but-almost-passed)-Help?p=1488497&viewfull=1#post1488497

Clean power is NOT cheap at $25~/bottle (and u need 2 bottles for a full tank), but it sure does clean up the ENTIRE fuel system and then some from tank to exhaust valves....

 

[nsxnut]

according to almost everything i read online NO emissions are increased if the engine is running hotter than it should.
seems to me, hotter the better for everything except NO.
i was so surprised by this, i kept looking and looking, and kept finding the same info on NO.
example

The EGR system's job is to re-route a small amount of exhaust gas back into the intake manifold to help reduce combustion chamber temperatures. As mentioned above NOx is created when combustion chamber temperatures reach above 2500F.

By recirculating exhaust gas back into the intake, a small amount of the air/fuel mixture is replaced with inert gas, reducing combustion temperatures.
http://www.smogtips.com/failed-high-NO-nitrous-oxide.cfm

The cats must be up to temperature for them to work. The help reduce NO
100 octane will help reduce combustion temperatures.
I suspect if there is any carbon buildup this will also help to raise combustion temperatures.

Good luck.

 

[willabeest]

OK but redline fuel additive will not destroy my 2 year old Cats? some fuel additive took out my first set of Cats (i think - who knows really)

 

[BATMANs]

NO they will NOT harm ANYTHING at all. I know this from decades of experience. If anything they do just the opposite.

That is my recommended course of action.

If you are still failing then it's most likely your cats.

I'm just going down the process of elimination.....

 

[willabeest]

some interesting info i found - racing gas

http://www.davebarton.com/Unleaded_Racing_Fuel_in_SoCal#Central_and_NorCal

http://www.racegas.com/fuelfinder

 

[BATMANs]

I get 100 octane here on Highway 84 near the MOST expensive zip in the USA according to Forbes 2013.

 

[Coconut]

OP, do you have larger picture of your avatar???

 

[ATERPAK]

I also had that problem at my last smog check. It's the only thing that failed the first time around. After heating up the CATS real good he tested it again. He turned off the TCS and then when he was running the test for the NOX, he then turned ON the A/C and the car passed. It seems that turning on the A/C induced a load on the car and the ECU compensated for it by introducing more fuel into the engine. That cooled the combustion temp. and since it was only testing for NOX, it didn't care about the HC's. As soon as it passed, he turned off the A/C and then the car passed. When you get a test for smog and it's tied to the DMV's computer, if one part fails, you get to test it again once more and only have to repeat the test that failed and not the other areas which passed. Getting the CATS hot is critical and also turning off the TCS. Thankfully we have a smog shop with techs. who know and love the NSX and have learned a few tricks to help when and if it's needed. I'm going to look into whether the EGR is working as it should and then trying new CATS. SMOG for us in CA is every 2 years and mine is due again at the end of 2014. Good luck with yours.

Al

 

[willabeest]

this is complicated. your story makes sense. seems to me running higher octane might also cool off the cylinders a little if your engine has a lot of miles (mine has 110K).
more miles = more carbon = higher compression = need higher octane.
shad went over my car, said the fuel filter was dirty, and some of the plugs looked bad. oil lube filter
cleaned the air cleaner, EGR looked OK.
i will attempt another smog check tomorrow or saturday.
if it fails again i just might put in unleaded racing gas 50/50 with chevron premium see if that lowers the cylinder temps a little.
i have a feeling it is going to pass, i was not that much over passing on NO.
seems to me just random error in the test would be +/- at least 30 PPM, which means if i test it enough times it might pass simply based on random error.

I also had that problem at my last smog check. It's the only thing that failed the first time around. After heating up the CATS real good he tested it again. He turned off the TCS and then when he was running the test for the NOX, he then turned ON the A/C and the car passed. It seems that turning on the A/C induced a load on the car and the ECU compensated for it by introducing more fuel into the engine. That cooled the combustion temp. and since it was only testing for NOX, it didn't care about the HC's. As soon as it passed, he turned off the A/C and then the car passed. When you get a test for smog and it's tied to the DMV's computer, if one part fails, you get to test it again once more and only have to repeat the test that failed and not the other areas which passed. Getting the CATS hot is critical and also turning off the TCS. Thankfully we have a smog shop with techs. who know and love the NSX and have learned a few tricks to help when and if it's needed. I'm going to look into whether the EGR is working as it should and then trying new CATS. SMOG for us in CA is every 2 years and mine is due again at the end of 2014. Good luck with yours.

Al

 

[Speedy93]

ideling wont get your cats hot enough. i was affraid of failing smog due to everything in my car, so i had it tested first before hooked up to DMV. the first try it barely passed, so we went for it, and the numbers were even better cause we got the cats hot from running it. and I too would like to see a bigger pic of your avitar :biggrin:

 

[willabeest]

ideling wont get your cats hot enough. i was affraid of failing smog due to everything in my car, so i had it tested first before hooked up to DMV. the first try it barely passed, so we went for it, and the numbers were even better cause we got the cats hot from running it. and I too would like to see a bigger pic of your avitar :biggrin:

my avatar was borrowed from an Italian NSX owner. he had the pics on a website once a long time ago, but the website is gone, and i never see him online anymore.
here are some more pics, same girl (me bad) i mean same woman, the first five pics are her, the rest of the pics are someone else

http://www.nsxprime.com/photopost/u11011-willabeest.html

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new law = cannot heat up cats before test.
(california)

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failed again worse after new plugs, air cleaner, oil change, filter, egr checked. i ran the car at 7000 RPM for 9 miles before they tested it. NO again, this time 835 measured, max is 785 at 15 MPH.
everything else passed great, for instance the NO at 25 MPH is 50% of max.
i think if i was retired, i would leave this $*(!ing state. i think NSX owners would be better off if it still belonged to Mexico.

 

[willabeest]

OK, car passed. to pass, i needed new O2 sensors, decarbonization with sea foam, octane booster, and finally putting a 16 inch rim (from the front) on the rear.
to put it another way, i changed the gearing by putting a smaller wheel on the back, which turns out to be the stock size. (remember, the stock 1992 NSX comes with 16 inch rear rims).
i had 17 inch non stock rims on the back, which made the gearing such that it was difficult to pass the 15 MPH. simply moved the front wheels to the rear. fortunately, i have two sets of 16 inch rims/tires.
i hope this helps others in the future. BTW my aftermarket cats were about 2 years old.

 

[Wizard]

Glad to hear you passed. Did you barely pass, or did you pass with flying colors this time?

 

[willabeest]

Glad to hear you passed. Did you barely pass, or did you pass with flying colors this time?

DIAGNOSTICS FOR FAILED EMISSIONS.
VEHICLE FAILLING NOX EMISSIONS:
15MPH 1454
25MPH 1077
ENGINE IN GOOD RUNNING CONDITION. FOUND
AFTERMARKERT O2 SENSORS SWITCHING AT B1
95MS BANK 2 90S, BORDERLINE PASS.
INSPECTED TOPS OF PISTONS WITH SCOPE,
FOUND EXCESSIVE CARBON BUILDUP RECOMMEND
TO PERFORM TOP ENGINE DECARBONIZATION.
AFTER DECARB NOX REDUCTION OF 500 PPM ON
15 & 25. RECOMMEND TO REPLACE
AFTERMARKET O2 SENSOR WITH PAIRED OE
SENSORS. AFTER O2 SENSOR REPLACEMENT
200PPM REDUCTION IN NOX, 25PPM OVFER
STANDARD. CUSTOMER INFORMED THAT THE
TIRES EQUIPPED ARE TALLER THAN STOCK
SIZE, RECOMMENDED TO INSTALL OE TIRES
AND RETEST. AFTER TIRE INSTALLMENT NOX
REDUCED TO 653, 130 POINT BELOW
STANDARD. SMOG TEST PASSED.

There is a copy/paste of everything we did. Hopefully the max allowances aren’t lowered any more that they have. Next step is to get a new set of catalytic converters installed.