ibkevin

Second re-test here, NOX was 103ppm over.

This time the tank is half 89 and half 91oct, made sure all post AFM joints are tight and pulled out 2.72deg of timing at the FQS.

Am I missing something?

slivel

Why do you run 89 octane? The car requires 91 or greater. For smog I heard of people mixing unleaded race fuel (100 octane) or combinations of ethanol , methanol, toluene, or some other which's brews, but never lowering the octane by mixing with 89. Just curious.

Btw, I just recently passed my check in San Diego with Vitesse Maf running V-FLEX+ chip, 83 lb/hr injectors, and unmixed 91 octane fuel in the tank. NOX readings were in the 600ppm range - about 140 ppm margin to the good.

doabarrelroll

91 octane only dude. I keep getting advice to make sure you drive for at least 30 minutes. My oil temperature took at least 25 minutes before reaching even 185 degrees.

PEvans

IMO NOx all comes down to your catalytic converter if you make the HC and CO numbers.

That said, last time I had my 951 smogged it easily made the 25 mph NOx but barely made the 15 mph NOx in first gear (2479 RPM) with a 2 yo DEC cat. I now need to pass again. I'm not totally sure what I should do ahead of time. Based on some posts here I'm thinking replace the O2 sensor and maybe check one more time for vacuum leaks. Mine is all stock and all original, but getting up there at 188k miles.

PEvans

Keep in mind that the NOx limit has gone from:

1992 ppm @ 15 mph/1792 ppm @ 25 mph in 1999 to
791 ppm @ 15 mph/730 ppm @ 25 mph now (or in 2009 anyway)

So the design and performance of our cars is what it is, meanwhile the NOx target is moving further away very quickly.

A little off topic, but I am interested in any opinions on whether aftermarket chips and engine mapping make sense just to get the "best" performance and lowest emissions from the engine you have, even if you are not interested in more HP or quicker response.

slivel

This, I really don't understand: your smog tester ran the 15 mph test in first gear. Mine ran it in 2nd gear at about 1500 rpm and seemed to be lugging the engine. When i asked him about it he said the regulations required him to do the test that way. The worst part is that they have tightened the limits twice since I have owned this car. And I agree that the 15 mph test is always a struggle to pass the NOx limits.

PEvans

Yeah, I don't understand it either. DEC told me there was only a fair chance my car would be able to pass after 4 years on the cat, but this seems like something is up with my car, not the cat.

BTW as to the "regulations," these guys are mostly morons (sorry). I have had my car disqualified because they thought the stock turbo exhaust was an illegal modification and because it is missing the emissions sticker on the underside of the hood (my hood has been replaced). So I pull my car out, pay the guy his $45 and say thank you very much, and go elsewhere.

The only thing that matters is what the sensor in the tailpipe says when the test is uploading data to the DMV. Fortunately I have a test place that at least so far will work with me testing the car hot and does not make up absurd "regulations."

ibkevin

How did you pass the visual?

Ex smog tech suggested I lower octane.. pulling out the timing should be the home run. The gearing in our cars and state requirements are making the 15mph damn near impossible. If it was an Auto, it should be a piece of cake.

NOX is currently at 689/730, 15/25mph. My HC and CO are under the Avg numbers, with a 2yo Magnaflow cat. Yeah I warm the car up and keep it running prior to the test.

Laust Pedersen

Good luck Kevin,

There are however a couple of ways to reduce the uncertainty.

One is to install an AFR gauge and make sure it dithers around stoichiometric when mimicking the test conditions and another is to train your nose to detect “cat” activity.

Pump gas octane rating has nothing to do with emissions, as long as there is no detonation.
So far I have passed every time on 87 octane.

My smog guy is pretty slow on all the setup formalities, so sometimes the car is unable to keep the cat active when standing still. He often asks for a pre-test and laughs at me, when I instead sniff the tail pipe. If the exhaust smells too bad I will go for a 15-20 min ride.

So far 100% success with this technique.

Laust

PEvans

Wow.

In 2008 I got 166 ppm NOx lugging in 2nd gear at 15 mph, but that was a brand-new DEC cat. So even with those numbers it is doable if you are willing to plunk down for a new cat every time.

ibkevin

I've learned to run my cat only for testing, e'ffem. Until they install air scrubbers on the border with TJ, air quality control is bull****.

PEvans

That is exactly the incentive they are creating. I never really wanted to do that, but 689 ppm NOx and only one supplier of replacement cats, it is stupid to actually use your cat for daily driving.

slivel

[QUOTE=ibkevin;9642471]How did you pass the visual?

Vitesse Stealth MAF

ibkevin

Good to hear from you Laust. I have the ProfecB Spec II but haven't picked up a new DB15male / RJ-12 adapter for the latest notebook. O2 dithers between .1 and .8

What did you do for Jboot?

Greendomize

FYI, Oxides of nitrogen are produced more heavily during high combustion temperatures. EGR helps to reduce this by occupying space in the cylinder and absorbing some of the heat released during combustion.