i have the notorious NOX problem, the co adjustment is completely closed the temp sensor is fine, the afm is reading what it should and i'm still getting over 1400 ppm for nox (1200 to pass) i have turned the little switch on the dme to the 3rd setting for a 6% richer and it actually went to 1900ppm with a little to no change in the other readings of the test.
i'm thinking of moving the barn door spring (loosening) to get a richer mixture that way. any thoughts would be helpfull yes i did search the archives thats where i came to adjust the dme switch for a richer mix but it didnt work. should i have turned it further for a retarding of the timing as well ? i am at wits end with this car and its emissions i know something else is the problem but i cannot find it. cat was replaced last year at this same time frame (it should last another year or two) 02 was done then as well.

is there any hope for this situation?

 

Hmm... I think mine had a problem with that two. Turned out that a previous mechanic opened up the air flow "box" and cleaned it and adjusted the coiled spring that was in there.

If yours has been opened before try tinkering that. Set it to the lowest setting possible but keep it high enough so that it does not stall when pressing the gas.

I hope that helps. If you want I can get some pictures tonight and circle the area that I'm talking about since I don't know all of the car terms yet. Send me a message if you'd like that as I may forget about this posting. I'm a wetback mechanic.

David
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
"What's that thingy? Can I press that button?"

 

A bad Cat. will cause you to fail on Nox. Also, bad valve seals.

 

tabor i think bad valve seal would also give me an indication of excessive oil consumption not to metion hard to start. the cat should not be bad it is an aftermarket cat but is one of the better ones.

i'l have to play with the flap spring tonight like the devil said to do

 

Here are a few general tips that may help you on emissions.

1. Fill your tank with Amoco Ultimate gasoline, its by far the cleanest burning (yes this does make a difference, my dad used to be in fuels development).

2. Make sure your Cat is hot when you go in for your test. Cats are most efficient and are designed to work when hot.

3. Check oxygen sensor, replace if you are at all unsure.

These should give you an extra edge on the emissions people . BTW, I hear that Pep Boys has some fuel additive that guarantees a pass on emissions. I've never tried it though. I would think that running a bottle of Techron through the engine might help too.

 

Also consider basics like plugs & wires, cap & rotor, air filter. If any of it's in suspicious condition, or of unknown age, replace it.

Hey, at least you'll have a fresh full tune-up by the time you pass....

Jim, photographic memory, no film....

 

went thru this last year too, replaced 02,wasnt bad, replace cat wasnt bad, now ive replace afm wasn bad, replaced temp sensor wasnt bad the only thing i havnt replace d is the injectors,dme,FPR,fuel damper speed sensors but then again i would think if something was wrong with them it wouldnt run.

were gonna have to be a little more creative with this thing

 

does whatever emmissions sniffer you are testing this with have the capability to read unburned hydrocarbons and interpolate to give your a/f ratio? at least then you'd know if you actually were running too lean... if you are rich or stoich already, your efforts to richen things up will likely not effect nox levels.

 

yes it has the readings for co,no,hc,and something other that i cant remeber right now.

i have, last year pulled the 02 plug to see what would happen my nox went down to a normal reading but the hc, and either co or the other thing that i cant remember, was way high so it leads me to find a happy medium between the co and nox. but the price for this testing is getting outrageous

 

Drive your car until almost empty and put a gallon of methyl alcohol (aka gasline antifreeze) into the tank to cut your fuel.
It's cheating but your car will pass.
<img src="graemlins/burnout.gif" border="0" alt="[burnout]" />

 

Did the alcohol thing 20 years ago, and it did work. I only used 1/2 gal in about the last 2 gal of gas in the tank. They spent 10 minutes looking for an exhaust leak because the car was running too clean! BTW, fill the tank afterwords to dilute the alcohol. Good luck

 

Hmmm, high NOx is usually caused by high combustion chamber temps, which themselves are usually caused by lean running. If you have one cylinder that runs lean for whatever reason, then the other 3 would run rich from the excess air from the lean cylinder. Until you unplug the O2 sensor and then the engine management quits trying to compensate and uses a preset curve that might eliminate the lean cylinder through increased injector pulse width but emissions would increase across the board.

I'd get your injectors cleaned and balanced.

Bryan

 

Hey were did you all get that methyl alcohol?

 

mine was like .02 when the limit in vegas is .25, so i did well . I dunno wut that tested tho, but my car wooped the tests *** like a doctor slappin a newborns ***. Wooohoo. to bad the engine pieces tried to have sex and broke the chastity belt.

 

Ask any automotive store if they can get it for you. (the methyl alcohol)
Seeing you're from the south they might look at you funny so don't call it gasline antifreeze.

So anyway, buy a gallon and mix it with a couple gallons of fuel. When your car is way too clean don't be surprised when they all stand around scratching their heads wondering why you're beating factory specs. (as long as your engine is tight and doesn't produce fumes you're okay)

And don't drink the stuff, you'll go blind
<img src="graemlins/oops.gif" border="0" alt="[oops]" /> <img src="graemlins/oops.gif" border="0" alt="[oops]" /> <img src="graemlins/oops.gif" border="0" alt="[oops]" /> <img src="graemlins/oops.gif" border="0" alt="[oops]" />