Help me out guys i need to know what part i need to replace
my emission result was the NOx did not passed.The standard is 1006 and my reading was 1564,i had 76k miles on the car.What should i replace or somebody give me some advice before i go to mechanic i dont want be rip off.HELP

Ron

Is your catalytic converter bad? Check that out, sometimes previous users will install a Midas converter to save money because the mercedes converter is very expensive

How do i check the catalic converter?Is it the one that cuz the NOx to fail.Thank you

Ron

My guess is that is one of many ways that can cause you to fail the nox test. Perhaps take the car to your mechanic or even midas and have them tell you if it is the original. If it does have a cheap converter (non mercedes) on, you can probably get by by just installing another midas converter.

Ironically NOx emissions can be too high if it's tuned for optimum fuel economy. The EGR valve contributes to the reduction of NOx.

Kuan

I'd change the O2 sensor and the cat. Is it running rich?

Have you changed your plugs recently? Do they look good, i.e. not fouled, black, etc. You MUST have the plugs firing properly to obtain a good smog reading. Does your smog report say that your timing is within spec.? If not, get that fixed. Is your air filter clean? Are all, and I mean all of your vacuum hoses o.k. Wiggle them at each end to be sure. You frequently get cracked ends that cause vacuum leaks. Is your computer readout telling you of any problems such as the O2 sensor? It doesn't sound like you have much of a problem as a bad one would have sky high readings. I would do the CAT at last resort as it is so expensive, but changing it would certainly get you through the test. Good luck!

I recently replaced the plugs,air filter,what is the connection of failed NOx to vacuum leaks?I dont have any check engine light.Any more input?

Ron

Ron,
NOx,is formed during high tempreture fuel
combustion.My guess is that your car is running
on the lean side.Have your Technician check your
fuel air ratio.

Clauser1

Another thing vaccum leaks contribute to make your car
run lean.

Clauser1

Clauser1:did you receive the cd?
What exactly is Nox?.How do you adjust the fuel/air ratio?
I think i need to replace the EGR valve?does it make sense?

Ron,
Yes I got the CD thanks.I advice that you see a
knwoledgeable MB mechanic.Dont change anything yet.
You cannot adjust air fuel ratio or mixture if you
dont have the right equipment.It might get worst.As far as I know its easier to deal w/ NOX than high CO2 and high
Hydro carbon.

Clauser1

NOx is the catchall for Nitrogen Monoxide(NO) and Nitrogen Dioxide(NO2). NO is colorless and tasteless but when exposed to air it becomes NO2, poisonous, red-brown, and stinky.

Like Clauser says, running hot is the main culprit in the generation of NOx emissions. This can be due to fuel mixture (running too lean), poor EGR, unusually high compression, overadvanced ignition.

Kuan

Try three or four tankfuls of REGULAR unleaded, providing that it does not ping or spark knock. The lower octane fuel burns more completely. Also, make sure your air filter element is clean or just replace it.