High NOx level, didn't pass emissions

[bobec]

Does any body knows what Nox means and how to fix that problem? i just changed spark plugs but that was after emissions and i have 1 more try to see if it passes so want to know what would fix NOx level.... and some times my RPM would jump when car is just standing like between 0 and 500....and than it goes back up to like 600 and just stays there

[ehsnils]

NOx is nitrous oxides, and they are caused by hot combustion.

 

That means that the engine may be running lean or that you have problems with the EGR valve if the car has one. Bad O2 sensor may also be a culprit, or a bad cat.

 

But the engine behavior indicates a leak, so check hoses and egr first.

[bobec]

where would i find EGR valve? and my friend says it is probably cat, because i have check engine like on it like flashes than it would blink 2 times really fast , than it would stop and do same thing over and over again.....

[ehsnils]

EGR = Exhaust Gas Recirculation, but not all vehicles have that so it may not exist on your car.

 

The flashing CEL may be a code, try to count the number of flashes, it shall be like two digits.

 

Look here for more information: http://legacycentral.org/library/literature/codes.htm

 

I did create a sticky thread on the subject too:

http://legacygt.com/forums/showthread.php/reading-obd-codes-146240.html

[bobec]

So after i changed spark plugs my NOx level went down from 7k to 5k but limit is 3k , so if i would change my air filter, spark plug wires, fuel filter, and oil, would that help to lower NOx? ohh and we connected computer to my car and it doesn't read any codes ..... but it flashes but no codes on the computer....

[ehsnils]

Check all vacuum hoses and if you have a MAF it shall be cleaned.

 

Run injector cleaner too, one tank or two and then test again.

 

But the CEL flashes are probably the codes you want, so try to read the flashings.

 

Connecting a computer to OBD1 may not always work.

[bobec]

how do i tell a code with out obd1? and i didn't had obd1 it was something kind computer that read obd1 obd2 and what ever other stuff =D and it showed nothing

[ehsnils]

The number of blinks on the CEL lamp. They come in groups, so just sit down and count. And they will repeat all the time.

 

Also see the instruction in the link I posted.

[code411]

Just retard your timing!

It works every time. As much as you can without making it run rough. 5-10deg. or so. You can raise the idle to compensate if you need to.

It really does work, I've seen it go from 900 ppm to less than 100ppm.

I re-tested the car 20mins. later and passed with flying colors.

I told the smog tech i replaced a vacuum hose and adjusted the timing.