I have done some research, but I wanted to get some additional tips on my specific situation. NOx at 1718, allowed is 907. HC is 133, allowed is 120. I was running regular with what should have been a 12 degree advance (though we changed the cap and rotor so it's not clear what exactly it was yet). The test was done with the engine at about 190 degrees.

I was just wondering what those readings mean. My CO was .49 and allowed is .67, my O2 was 2.8 and my CO2 was 11.0. I'm currently taking the following actions to fix the problems.

First i'm going to retard the timing down to at least 0 degrees, maybe less.
I'm going to lower my idle speed back a bit.
I'm going to run premium and at least one bottle of cleaner/octane booster during test.
I'm also going to get my fan switch fixed so it's not running constantly with my manual toggle switch. This should make the car run hotter

My cat is new, my spark plugs are new. I've yet to check to make sure they're all firing with a temp gun. I dont put out any smoke at all, startup or otherwise, and my engine is pretty much a stock L03 still. With those specs, is my course of action a good one or missing something? Does those readings indicate a bad O2 sensor despite not throwing a code? Is there another method of passing the emissions test without paying for the sticker under the table? I am using that GTP emissions fluid but all that is is a cleaner.

I'm pretty sure backing off the timing and idle speed and running premium should do the trick, but I dont get any practice shots at this and i'm not sure yet what NJ does when you fail twice. Thanks in advance.

 

They impound your car and take it to the crusher.

No, just kidding. I think NJ has limits on how much they can force you to spend to at least TRY to fix an emissions failure. Here in PA it's about $200 before they give you the wiaver. I always take my cars in the first time without doing any tune-up to them. That way if I fail I just have the shop replace parts I was going to replace anyway AND TEY COUNT TOWARDS THE WAIVER.

Agreed, if it's a stock L03 you need that timing down a lot lower than you've got it. Set it to stock for emissions testing.

How are you adjusting idle speed on a computer-controlled TBI? You know you don't want to just start turning on the screw like you do with a carb- that throws things out of whack on a computer controlled engine. Idle speed should only be changed in the chip programming, not by physical adjustment.

 

well, at the time, the car was stalling (now I know it was likely due to the spark plug wires completely broken on half of the engine) in the winter, so being without a programmer, I just turned up the idle screw. This worked for the time being. Now I realize after replacing the spark plug cables (they looked fine but broke in half when i touched them) that the idle speed adjustment i made was probably unecessary.

 

JUST BUY THE STICKER AND ROLL............


NO REALLY YOU CAN BE CHASING THAT PROBLEM DOWN FOREVER , OUT HERE CROOKED SMOG CERTS CAN COST A FORTUNE ($300). SOMETIMES CHEAPER THAN CHANGING EVERYTHING. I CANT LIE I BOUGHT MINE.

 

If I remember right, the measurments that you have there are in parts per million, or more commonly referred to as ppm. The max allowed to pass with NOx (Noxious Gases) is 907 parts per million, and you had almost double the allowed.

I would set the timing as previously stated, fill the tank with high-octane, and let her run hot before you try again.

Off-topic: Why do people feel the NEED TO YELL ALL THE TIME.

 

ok, So it seems i'll definitely need to replace my fan switch on the engine block, since there is no other way I can run hot and not risk overheating during the test. With the fan on all the time, it runs at around 180-190 degrees.

I know the general idea behind running high octane is that less fuel is burned per rpm, thus the emissions are lower. But what causes high nitrous oxide readings?

Can someone post what they got for each of the gasses on a test that passed with a similar car? Maybe even a before (failed) and after (passed just by detuning and running high octane). That would be very informative.

 

NOx is generated when combustion temps are elevated. Advancing the spark will elevate NOx readings as will having a non-functional EGR system (EGR systems were designed specifically to lower NOx emissions and for no other reason).

 

yea, hrm.. I dont know of any real way to determine if the EGR system is working or not.
Also, if combustion temps are high and cause NOx, why do we want to run the car as hot as possible to pass? to just lean it out?

 

Don't confuse engine operating temp with combustion tems- different processes at work, different reasons, different end results.

 

I agree with Damon. Give the egr vacuume and make sure its functioning. also make sure the passage isnt carboned up reducing flow. Nigh oxides of nitrogen is from high combustion temp and adding an inert gas (exhaust) cools it down when not under high load. It is sort of a pain to check and clean on these cars.